SECTION VIII.. The Skin and the Sense-Organs.

THE SKIN AND THE SENSE-ORGANS.

THE SKIN AND THE SENSE-ORGANS.

LITERATURE.

I. THE SKIN.

*Ascherson*, Ueber die Hautdrüsen der Frösche. Arch. f. Anat. u. Physiol. 1810, p. 15.

*Axmann*, Beiträge zur mikroskopischen Anatomie und Physiologie des Ganglien-nervensystems. 1853.

*de Betta*, Erpétologia delle provincie Venete e del Tirolo meridionale. 1857.

*Biesiadecki*, Ueber Basenbildung und Epithelregeneration an der Schwimmhaut des Frosches. Untersuchungen aus d. Krakauer path.-anatom. Institut. 1872, pp. 60–84. Abstract in Centralbl. f. d. med. Wiss. 1873, No. 7, p. 106.

*Bimmermann, E. H.*, Ueber den Einfluss der Nerven auf die Pigmentzellen des Frosches. Dissert. Strasburg, 1878.

*Bimmermann, E. H.*, Ueber den Einfluss der Nerven auf die Pigmentzellen des Frosches. Centralbl. f. d. med. Wiss. 1879, p. 545.

*de Blainville, M. H. M. Ducrotay*, De l’Organisation des animaux. Paris, 1822, pp. 142, 225.

*Bolaw*, Beitrag zur Kenntniss der Amphibienhaut. Göttingen, 1866.

*Bruch*, Beiträge zur Naturgeschichte und Classification der nackten Amphibien. Würzburger naturwiss. Zeitsch. 1864. Vol. III.

*Brücke*, Untersuchungen über den Farbenwechsel des afrikanischen Chamaeleon. Sitzungsb. der Wiener Acad. 1852. Vol. IV, p. 196.

*Bugnion*, Recherches sur les organes sensitifs qui se trouvent dans l’épiderme du Protée et de l’Axolotl. Dissert. Zürich.

*Canini, A.*, Die Endigungen der Nerven in der Haut des Froschlarvenschwanzes. Arch. f. Anat. u. Physiol. 1880, pp. 143–153.

*Ciaccio, J. V.*, Intorno alla minuta fabbrica della pella della Rana esculenta. Palermo, 1866. Giornale di Scienze naturali ed economiche. Vol. II, pp. 103–158.

*Ciaccio, J. V.*, On the distribution of the nerves to the skin of the frog, with physiological remarks on the ganglia connected with the cerebro-spinal nerves. Trans. Micros. Soc. London, 1864. Vol. XII, pp. 15–31.

*Czermak, J. N.*, Ueber die Hautnerven des Frosches. Arch. f. Anat. u. Physiol. 1849, p. 252.

*Da Collin*, Danemarks Froer og Tudser. Naturhist. Tidsskrift. 1870.

*Dewitz*, Ueber das verschiedene Aussehen der gereizten und ruhenden Drüsen im Sehenballe des Laubfrosches. Biol. Centralbl. 1883, p. 558.

*Dogiel*, Neue Untersuchungen über den pupillenerweiterden Muskel, etc. Arch. f. mik. Anat. 1886. Vol. XXVII, p. 403.

*Duméril* et *Bibron*, Erpétologie générale. 1841. Vol. VIII.

*Eberth, C. J.*, Untersuchungen zur normalen und path. Anatomie der Froschhaut. Leipzig, 1869.

*Eberth, C. J.*, Zur Entwickelung der Gewebe im Schwanze der Froschlarven. Arch. f. mik. Anat. 1866. Vol. II, pp. 490–503.

*Eckhard*, Ueber den Bau der Hautdrüsen der Kröten und die Abhängigkeit der Entleerung ihres Secretes vom centralen Nervensystem. Arch. f. Anat. u. Physiol. 1849.

*Ehrmann, S.*, Ueber Nervenendigungen in den Pigmentzellen der Froschhaut. Sitzungsb. der Wiener Acad. 1882. Vol. LXXXIV, Pt. III, pp. 165–170.

*Engelmann, T. W.*, Pflüger’s Arch. f. d. ges. Physiol. 1871, Vol. IV, p. 321, and 1872, Vol. V, pp. 500–513. (Contractile glands in skin of frog.)

*Harless, E.*, Ueber die Chromatophoren des Frosches. Zeitsch. f. wiss. Zool. 1854, Vol. V, p. 372; also in Münchener Gelehrten Anzeiger, 1853, No. 35.

*Harley, G.*, On the organs of cutaneous respiration; principally on those of Rana temporaria. Trans. Micros. Soc. London, 1857. Vol. V, p. 148.

*Hensche, A.*, Ueber die Drüsen und glatten Muskeln in der äusseren Haut von Rana temporaria. Zeitsch. f. wiss. Zool. 1856. Vol. VII, p. 273.

*Henslow*, Way in which toads shed their skin. Annals of Nat. History, 1850, p. 69.

*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs. Leipzig und Heidelberg, 1873–1878. Vol. VI.

*Huber, O.*, Ueber Brustwarzen bei Rana temporaria, L. Zeitsch. f. wiss. Zool. 1887. Vol. XLV, p. 664.

*Huizinga, D.*, Untersuchungen über die Innervation der Gefäsze in der Schwimmhaut des Frosches. Pflüger’s Arch. 1875. Vol. XI, p. 207.

*Huxley, T. H.*, Tegumentary organs. Todd and Bowman’s Cyclopædia of Anat. and Physiol. p. 500.

*Klein, E.*, On the lymphatic system of the skin and mucous membranes. Quart. Journ. Micros. Sci. 1881. Vol. XXI, pp. 379–406.

*Kölliker, A.*, Stiftchenzellen in der Epidermis von Froschlarven. Zoolog. Anzeiger. 1885.

*Krause*, Handbuch der Gewebelehre. 1862.

*Krukenberg, C. F. W.*, Die Hautfarbstoffe der Amphibien, in Vergleich. Physiol. Studien, by same author, 1882, pp. 43–49.

*Kutschenko, N.*, Ueber die Krappfärbung der Froschgewebe. Arch. f. mik. Anat. 1882. Vol. XXVIII, pp. 360–364.

*Langer*, Ueber das Lymphgefässsystem des Frosches. Wiener Sitzungsberichte. 1867. Vol. LV, pp. 593–636.

*Langerhans*, Anat.-hist. Untersuchungen über Fische und Reptilien. Berlin, 1853. Journal de Medicine. Vol. XI.

*Leboucq, H.*, Recherches sur le développement et la terminaison des nerfs chez les larves des Batraciens. Bull. de l’acad. roy. de Belgique. 1876. Vol. XLI, p. 4.

*Leydig, F.*, Histologisch-anatomische Untersuchungen über Fische und Reptilien. 1853.

*Leydig, F.*, Tastkörperchen und Muskelstruktur. Arch. f. Anat. u. Physiol. 1856, pp. 150–159.

*Leydig, F.*, Lehrbuch der Histologie. 1857.

*Leydig, F.*, Ueber die Nervenendigung in den sogenannten Schleimkanälen der Fische und über entsprechende Organe der durch Kiemen athmenden Amphibien. Arch. f. Anat. u. Physiol. 1861.

*Leydig, F.*, Ueber die Organe eines sechsten Sinnes. Nov. act. acad. Leop. Carol. 1868. Vol. XXXIV, pp. 1–102.

*Leydig, F.*, Ueber die allgemeinen Bedeckungen der Amphibien. Arch. f. mik. Anat. 1876. Vol. XII, p. 119.

*Leydig, F.*, Ueber die Schleichenlurche. Zeitsch. f. wiss. Zool. Vol. XVIII.

*Leydig, F.*, Ueber die Schwanzflosse, Tastkörperchen und Endorgane der Nerven bei Batrachiern. Arch. f. mik. Anat. 1876. Vol. XII, pp. 513–527.

*Leydig, F.*, Die anuren Batrachier der deutschen Fauna. Bonn, 1877, p. 123.

*Lister, J.*, On the cutaneous pigmentary system of the frog. Phil. Trans. 1857. Vol. CXLVIII, p. 627.

*Macallum, A. B.*, The nerve terminations in the cutaneous epithelium of the tadpole. Quart. Journ. Micros. Sci. 1886. Vol. XXVI, p. 53.

*Mayer, A.*, Ueber das Epithelium bei den Amphibien. Froriep’s Notizen, 1839. Vol. IX, coll. 49–51.

*Menke*, Rana rubita, Linn. Zeitschr. Isis von Oken. 1827. Vol. XX, p. 172.

*Merkel*, Ueber die Endigungen der sensiblen Nerven in der Haut der Wirbelthiere. Rostock, 1880.

*Meyer*, Ueber die Abhängigkeit der Gefässe und Pigmentzellen beim Frosch von dem Nerveneinfluss. Virchow’s Arch. 1854. Vol. VI, p. 581.

*Openchowski, T.*, Histologisches zur Innervation der Drüsen. Pflüger’s Arch. 1882. Vol. XXVII, pp. 223–232.

*Pfitzner, W.*, Die Epidermis der Amphibien. Morph. Jahrb. 1880. Vol. VI, p. 469.

*Rainey*, On the structure of the cutaneous follicles of the toad. Quart. Journ. Micros. Sci. Vol. III, p. 257.

*Roesel*, Historia natur. rana. nostrat. Nürnberg, 1758, p. 3, etc.

*Rudneff*, Ueber die epidermiodale Schicht der Froschhaut. Arch. f. mik. Anat. 1865. Vol. I, p. 295.

*Sattler, E. E.*, Die Verwendung des Lapisstiftes zur Untersuchung der Epithelien. Arch. f. mik. Anat. 1882. Vol. XXI, p. 672.

*Schneider*, Historia amphibiorum. 1739.

*Schultze, F. E.*, Epithel und Drüsenzellen. Arch. f. mik. Anat. 1867. Vol. III, p. 145.

*Schultze, F. E.*, Ueber cuticulare Bildungen und Verhornung von Epithelzellen bei den Wirbelthieren. Arch. f. mik. Anat. 1869. Vol. V, p. 295.

*Schultze, M.*, Ueber die Nervenendigung in der Netzhaut des Auges bei Menschen und Thieren. Centralbl. f. med. Wiss. 1869, p. 885.

*Stieda, L.*, Ueber den Bau der Haut des Frosches. Arch. f. Anat. u. Physiol. 1865, pp. 52–66.

*Stricker, S.*, and *Spina, A.*, Untersuchungen über die mechan. Leistungen d. acinösen Drüsen. Wiener med. Jahrb. 1880, p. 355; und Wiener Sitzungsb. 1880. (Skin and Membrana nictitans.)

*Swammerdam, J.*, Biblia naturae. Vol. II, p. 808.

*Szcesny*, Beiträge zur Kenntniss der Textur der Froschhaut. Dissert. inaug. Dorpat, 1867.

*Turner*, Way in which toads shed their skins. Annals of Nat. History, 1850, p. 430.

*Wagner, R.*, Handwörterbuch der Physiologie. Vol. III, p. 389.

*Walter*, Ueber die Drüsen des Daumenballens des Froschmännchens. Verhandl. d. naturf. Vereins der pr. Rheinlande und Westphalen. 1851, p. 351.

*v. Wittich*, Die grüne Farbe der Haut unserer Frösche, etc. Arch. f. Anat. u. Physiol. 1854, p. 41.

*v. Wittich*, Entgegnung auf Herm. Harless’s über die Chromatophoren des Frosches. Arch. f. Anat. u. Physiol. 1854, p. 264.

II. SPECIAL ORGANS OF TACTILE SENSATION.

a. The lateral sense-organs.

*Beard, J.*, On the segmental sense-organs of the lateral line and on the morphology of the vertebrate auditory organs. Zool. Anz. 1884. Vol. VII, p. 162.

*Bugnion, E.*, Recherches sur les organes sensitifs qui se trouvent dans l’épiderme du Protée et de l’Axolotl. Dissert. inaug. Zürich. Tire du Boll. No. 7, de la société vaucloise des Sc. nat. Vol. XII. Lausanne, 1873. Verhandl. d. schweiz. naturforsch. Gesells. Zürich, 1873. Vol. LVI, p. 49.

*Froriep, A.*, Ueber Anlagen von Sinnesorganen am Facialis, Glossopharyngeus und Vagus. Arch. f. Anat. u. Physiol. 1885.

*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs. Leipzig and Heidelberg, 1873–1878.

*v. Kölliker, A.*, Ueber neue Sinnesorgane von Froschlarven. Sitzungsb. Würzburg. 1885, p. 79.

*Krause, W.*, Die Nervenendigung innerhalb der terminal Körperchen. Arch. f. mik. Anat. 1880. Vol. XIX, pp. 53–137.

*Leydig, F.*, Ueber die Organe eines sechsten Sinnes. Nova acta Acad. Leopold. Carol. Dresden, 1868. Vol. XXXIV, pp. 1–102.

*Leydig, F.*, Ueber die allgemeinen Bedeckungen der Amphibien. Arch. f. mik. Anat. 1875. Vol. XII, pp. 513–527.

*Leydig, F.*, Ueber Tastkörperchen und Muskelstructur. Arch. f. Anat. u. Physiol. 1856, p. 150.

*Malbranc, M.*, Bemerkung betreffend die Sinnesorgane der Seitenlinie der Amphibien. Centralbl. f. med. Wiss. 1875, p. 5.

*Malbranc, M.*, Von der Seitenlinie und ihren Sinnesorganen bei Amphibien. Zeitsch. f. wiss. Zool. 1876. Vol. XXVI, pp. 24–86.

*Schultze, F. E.*, Ueber die Nervenendigung in den sogenannten Schleimkanälen der Fische und über entsprechende Organe der durch Kiemen athmenden Amphibien. Arch. f. Anat. u. Physiol. 1861, p. 759.

*Schultze, F. E.*, Ueber die Sinnesorgane der Seitenlinie bei Fischen und Amphibien. Arch. f. mik. Anat. 1870. Vol. VI, p. 62.

b. The touch-corpuscles of Golgi.

*Golgi, C.*, Della terminazione dei nervi nei tendini e di un nuovo apparato nervoso terminale musculo-tendineo. Atti della Società Italiana di scienze naturali. Milan, 1879. Vol. XXI; and abstracted in Centralbl. f. med. Wiss. 1879, p. 725.

*Golgi, C.*, Intorno alla distribuzione e terminazione dei nervi nei tendini dell’ uomo e di altri vertebrali. Estratto dai Rendiconti del R. Istituto Lombardo. Serie II. Vol. XI. Fasc. IX. Milan, 1878. Abstract in Centralbl. f. med. Wiss. 1879. Vol. 41, p. 725.

*Löwe, L.*, Ueber eine eigenthümliche Art von Gelenknervenkörperchen beim Frosch. Arch. f. mik. Anat. 1880. Vol. XVI, p. 613.

III. THE ORGANS OF TASTE.

*Beale, L. S.*, New observations upon the minute anatomy of the frog’s tongue. Phil. Trans. 1865, p. 443.

*Biedermann, W.*, Ueber morphologische Veränderungen der Zungendrüsen des Frosches, etc. Wiener acad. Sitzungsb. 1882. Vol. LXXXVI, Pt. III, p. 67.

*Billroth, T.*, Ueber die Epithelzellen der Froschzunge, etc. Arch. f. Anat. u. Physiol. 1858, p. 159.

*Engelmann, T. W.*, Ueber die Endigungsweise der Geschmacksnerven des Frosches. Centralbl. f. med. Wiss. 1867, p. 785.

*Engelmann, T. W.*, Ueber die Endigungen der Geschmacksnerven in der Zunge des Frosches. Zeitsch. f. wiss. Zool. 1868. Vol. XVIII, p. 142.

*Engelmann, T. W.*, Die Geschmacksorgane. Stricker’s Handbuch der Gewebelehre. 1872.

*Fixsen, C.*, De linguae raninae structura. Dorpat, 1857.

*Gottschau, M.*, Ueber Geschmacksorgane der Wirbelthiere. Biol. Centralbl. 1882, pp. 240–248.

*Hartmann, R.*, Ueber die Endigungsweise der Nerven in den Papillae fungiformes der Froschzunge. Arch. f. Anat. u. Physiol. 1863, p. 634.

*Hoyer*, Mikroskopische Untersuchungen über die Zunge des Frosches. Arch. f. Anat. u. Physiol. 1859, p. 481.

*Hoyer*, Ueber die Epithelzellen der Froschzunge, etc. Arch. f. Anat. u. Physiol. 1858, p. 163; also in Deutscher Klinik, 1857. No. 21.

*Hyrtl*, Ueber abwickelbare Gefässknäuel in der Zunge der Batrachier. Wiener Acad. Sitzungsb. 1863. Vol. XLVIII, Pt. I, p. 437.

*Key, E. A.*, Ueber die Endigungsweise des Geschmacksnerven in der Zunge des Frosches. Arch. f. Anat. u. Physiol. 1861, p. 329.

*Lépine* (On the nerve supply of the glands of the tongue). Arbeiten aus d. physiol. Anstalt zu Leipzig, 1870, p. 113.

*Molin, R.*, Ueber die Theilung der Nervenprimitivröhren in den Papillae fungiformes der Froschzunge. Wiener acad. Sitzungsb. 1849. Vol. III, p. 183.

*Schultze, F. E.*, Die Geschmacksorgane der Froschlarven. Arch. f. mik. Anat. 1870. Vol. VI, p. 407.

*Waller, A.*, Minute structure of the organ of taste in vertebrate animals. Proc. Roy. Soc. 1848. Vol. V, p. 751.

*Waller, A.*, Minute structure of the papillae and nerves of the tongue of the frog and toad. Phil. Trans. 1848. Pt. I, p. 139.

*Waller, A.*, Microscopic examination of some of the principal tissues of the tongue, etc. Phil. Mag. 1847. Vol. XXX, p. 277.

IV. THE NOSE.

*Babuchin*, Das Geruchsorgan, in Stricker’s Handbuch der Gewebelehre. 1872, p. 964.

*de Blainville, M. H. M. Ducrotay*, L’Organisation des animaux. Paris, 1822, p. 328.

*Blaue, J.*, Untersuchungen über den Bau der Nasenschleimhaut bei Fischen und Amphibien, namentlich über Endknorpel als Endapparate des Nervus olfactorius. Arch. f. mik. Anat. 1884. Vol. XXX, pp. 231–309. Zool. Anzeiger. Vol. V, pp. 657–680.

*Born, G.*, Ueber die Nasenhöhlen und den Thränennasengang der Amphibien. Morph. Jahrb. 1875. Vol. II, p. 4.

*Born, G.*, Ueber die Nasenhöhlen und den Thränennasengang der Amphibien. Breslau. Habilit.-Schrift. 1877.

*Born, G.*, Die Nasenhöhlen und der Thränennasengang der amnioten Wirbelthiere. Morph. Jahrb. 1879. Vol. V, p. 62. 1882. Vol. VIII, pp. 188–232.

*v. Brunn*, Die Membrana limitans olfactoria. Centralbl. f. med. Wiss. 1874, p. 709.

*v. Brunn*, Untersuchungen über das Riechepithel. Arch. f. mik. Anat. 1875. Vol. XI, pp. 468–478.

*v. Brunn*, Weitere Untersuchungen über das Riechepithel u. sein Verhalten zum N. olfactorius. Arch. f. mik. Anat. 1880. Vol. XVII, p. 141.

*Cisoff*, Zur Kenntniss der Regio olfactoria. Centralbl. f. med. Wiss. 1874, pp. 689–691.

*Cisoff*, Zur Frage über die Endigung der Riechnerven beim Frosche. Arbeiten der naturf. Gesells. an der Universität Kassan. 1879. Vol. VIII (in Russian).

*Clarke, J. Lockhart*, Ueber den Bau des Bulbus olfactorius und der Geruchsschleimhaut. Zeitsch. f. wiss. Zool. 1862. Vol. XI, p. 31.

*Colossanti*, Untersuchungen über die Durchschneidung des N. olfactorius bei Fröschen. Arch. f. Anat. u. Physiol. 1875.

*Dirkinck-Holmfield-Christmas, J.*, Experimentalle Undersögelen Bijgningen. Nordiskt medicinskt Arkiv., 1883. Vol. XXVI, pp. 50–60.

*Dogiel, A.*, Ueber die Drüsen der Nasenschleimhaut, besonders die Bowmanschen Drüsen. Arch. f. mik. Anat.

*Dogiel, A.*, Ueber den Bau des Geruchsorgans bei Garroirren, Knochenfischen, und Amphibien. Arch. f. mik. Anat. 1887. Vol. XXIX, p. 74.

*Dogiel, A.*, Ueber den Bau des Geruchsorgans bei Fischen und Amphibien. Biol. Centralbl. Vol. I, pp. 428–431.

*Dogiel, A.*, Ueber die Drüsen d. Regio olfactoria. Arch. f. mik. Anat. 1885. Vol. XXVI, p. 50.

*Ecker, E.*, Bericht über die Verhandl. der Gesellschaft für Beförd. der Naturw. zu Freiburg, 1855, p. 199; and in Zeitsch. f. wiss. Zool. 1856, Vol. VIII, p. 303.

*Eckhard, C.*, Beiträge zur Anatomie und Physiologie. Pt. I, 1855, p. 77.

*Eckhard, C.*, Ueber die Endigungsweise der Geruchsnerven. Beiträge zur Anat. u. Physiol. Giessen, 1882. Vol. I, p. 77.

*Erichsen, J.*, De textura nervi olfactorii ejusque ramorum. Dissert. inaug. 1857.

*Exner, S.*, Untersuchungen über die Riechschleimhaut des Frosches. Sitzungsb. der Wiener Acad. 1871. Vol. LXIII, Pt. II, p. 44.

*Exner, S.*, Weitere Studien über die Structur der Riechschleimhaut bei Wirbelthieren. Sitzungsb. der Wiener Acad. 1872. Vol. LXV, Pt. III, p. 7.

*Exner, S.*, Fortgesetzte Studien über die Endigungsweise des Geruchsnerven. Sitzungsb. der Wiener Acad. 1878. Vol. LXXVI, Pt. III, p. 171.

*Gastaldi*, Nuove Ricerche sovra la terminazione del nervo olfatt. Mem. della reale Acad. della scienze di Torino. 1858. Vol. XVII, Series II, p. 369.

*Hoffmann*, Lehrbuch der Anatomie der Sinnesorgane.

*Hoffmann, C. K.*, Ondersockingen over den anat. bouw van de membrana olfactoria en het periph. uitiende van den Nervus olfactorius. Dissert. inaug. 1866.

*Hoffmann, C. K.*, Amphibia in Bronn’s Klassen und Ordnungen des Thierreichs. Leipzig und Heidelberg, 1873–1878. Vol. VI, pp. 335–347.

*Horn, H.*, Ueber die Endschlingen des Geruchsnerven (nervus olfactorius) der Rana temporaria. Arch. f. Anat. u. Physiol. 1850.

*Hoyer, H.*, De tunica mucosa narium textura. Dissert. inaug. Berol., 1857.

*Hoyer, H.*, Ueber die mikroskopischen Verhältnisse der Nasenschleimhaut, etc. Arch. f. Anat. u. Physiol. 1860, p. 50.

*Langer, C.*, Ueber das Lymphgefässsystem des Frosches. Wiener Acad. Sitzungsb. 1867. Vol. LV, Pt. I, p. 615.

*Legal, E.*, Die Nasenhöhlen und der Thränennasengang der amnioten Wirbelthiere. Morph. Jahrb. 1882. Vol. VIII, p. 353.

*Martin*, Studies from the physiological laboratory in the University of Cambridge. Pt. I. 1873.

*Paschutin, V.*, Ueber den Bau der Schleimhaut der Regio olfactorio beim Frosch. Medicinisky Wjestnik. 1872. Nos. 38–40.

*Paschutin, V.*, Ueber den Bau der Schleimhaut der Regio olfactoria des Frosches. Arbeiten aus d. phys. Laborat. Leipzig, 1873.

*Paulsen, E.*, Ueber die Drüsen der Nasenschleimhaut besonders die Bowman’schen Drüsen. Arch. f. mik. Anat. 1886. Vol. XXVI, pp. 307–321.

*Piersol, G. A.*, Beiträge zur Histologie der Harderschen Drüsen der Amphibien. Arch. f. mik. Anat. 1887. Vol. XXIX, p. 594.

*Reichert, B.*, Arch. f. Anat. u. Physiol. 1857, p. 39. Bericht.

*Schultze, M.*, Ueber die Endigungsweise des Geruchsnerven und die Epithelial-gebilde der Nasenschleimhaut. Monatsb. Acad. z. Berlin. 1856, p. 504.

*Schultze, M.*, Untersuchungen über den Bau der Nasenschleimhaut, namentlich die Structur und Endigungsweise der Geruchsnerven bei dem Menschen und den Wirbelthieren. Halle, 1862. Vol. VII, pp. 32–41; also published in Berlin, 1875. Abstract in Centralbl. f. med. Wiss. 1863, p. 97.

*Seeberg*, Disq. microsc. de textura membr. pitnit. nasi. Dorpat, 1855. Dissert. inaug.

*Stirling, W.*, and *Macdonald*, The minute structure of the palatine nerves of the frog and the termination of nerves in blood-vessels and glands. Journ. of Anat. and Physiol. 1884. Vol. XVII, p. 293.

*Wiedersheim, R.*, Ueber die Kopfdrüsen der Amphibien. Sitzungsb. d. phys.-med. Gesell. in Würzburg, 1876. Febr. 5.

*Wiedersheim, R.*, Die Kopfdrüsen der geschwänzten Amphibien und die Glandula intermaxillaris der Anuren. Zeitsch. f. wiss. Zool. 1876. Vol. XXVII, pp. 1–50.

*Wiedersheim, R.*, Lehrbuch der vergl. Anatomie der Wirbelthiere. Pt. I. Jena, 1882.

V. THE EAR.

*Chatin, J.*, Recherches pour servir a l’histoire du noyau dans l’épithelin auditif des batrachiens. Annales des sciences nat. Zool. 1883. Vol. XVI, Series VI, Art. No. 2.

*Comparetti, A.*, in gymnasio patavino observationes anatomicae de aure interna comparatae. Patavii, 1789.

*Crombie, J. M.*, On the membrana tympani. Journ. of Anat. and Physiol. 1883, pp. 523–536.

*Cuvier, G.*, Leçons d’anatomie comparée. Paris, 1800. Vol. II.

*Deiters, O.*, Ueber das innere Gehörorgan der Amphibien. Arch. f. Anat. u. Physiol. 1862, p. 277.

*Eberth, C. J.*, Zur Kenntniss der Verbreitung der glatten Muskelfasern (Tympanic membrane). Zeitsch. f. wiss. Zool. 1863. Vol. XII, p. 364.

*Ferré*, Étude sur la crête auditive chez les vertébrés. Ann. Sci. Nat. Bordeaux. Vol. I, No. III.

*Hasse, C.*, Die Histologie des Bogenapparates und des Steinsacks der Frösche. Zeitsch. f. wiss. Zool. 1868. Vol. XVIII, p. 71.

*Hasse, C.*, Das Gehörorgan der Frösche. Zeitsch. f. wiss. Zool. 1868. Vol. XVIII, p. 359.

*Hasse, C.*, Das knöcherne Labyrinth der Frösche. Anatomische Studien, 2nd Pt. 1872, p. 377.

*Hasse, C.*, Die vergleichende Morphologie und Histologie des häutigen Gehörorgans der Wirbelthiere. Supplement to the Anatomische Studien. Vol. I, 1873.

*Hasse, C.*, Die Lymphbahnen des inneren Ohres der Wirbelthiere. In the Anatomische Studien of Hasse, 1873. No. XIX.

*Hasse, C.*, Das Gehörorgan der Wirbelthiere von Gustav Retzius. Arch. f. Ohrenheilk. 1884. Vol. XXI, pp. 314–324.

*Hoffmann*, Lehrbuch der Anatomie der Sinnesorgane.

*Hoffmann*, Bronn’s Klassen und Ordnungen des Thierreichs. Leipzig and Heidelberg, 1873–1878. Vol. VI, pp. 304–335.

*Ibsen, J.*, Anatomiske Undersögelser over orets Labyrinth. Udgivet vet P. L. Panum. Kjöbenhawn, 1846 (abstract in Virchow and Hirsch’s Jahresb. 1881, p. 88).

*Kuhn*, Ueber das häutige Labyrinth der Amphibien. Arch. f. mik. Anat. 1880. Vol. XVII, pp. 479–550.

*Kuhn*, Zur Anatomie des inneren Ohres der Wirbelthiere. Compt. rend. du III Congrès internat. d’Otologie à Bàle, 1884, pp. 228–238.

*Leydig, F.*, Lehrbuch der Histologie des Menschen und der Thiere. Frankfurt a. M. 1857.

*Leydig, F.*, Ueber neuere den Aquaeductus vestibuli des Menschen und der Thiere betreffende Forschungen. Sitzungsb. d. Niederrheinischen naturf. Gesellsch. in Bonn, 1874. Vol. XXXIV, p. 124.

*Moldenhauer*, Vergleichende Histologie des Trommelfells. Arch. f. Ohrenheilk. 1878, p. 1.

*Pappenheim, S.*, Ueber Verbreitung der Flimmerbewegung. Arch. f. Anat. u. Physiol. 1840, p. 533.

*Retzius, G.*, On hörselnervens ändningssätt i maculae och cristae acusticae. Nordiskt medicinskt arkiv. 1871. Vol. III.

*Retzius, G.*, Zur Kenntniss der Morphologie des inneren Ohres bei Wirbelthieren. Nord. Med. Ark. 1880. Vol. XII, No. 12.

*Retzius, G.*, Zur Kenntniss des Gehörorgans der Wirbelthiere. Arch. f. Anat. u. Physiol. 1880, pp. 235–244.

*Retzius, G.*, Das Gehörorgan der Wirbelthiere. Pts. I and II, 1881. Stockholm.

*Retzius, G.*, Das Gehörorgan der Wirbelthiere. Congr. internat. de Copenhagen. Anatomy, p. 29.

*Retzius, G.*, Das Gehörorgan der Fische und Amphibien. Pt. I, 1881. Stockholm.

*Retzius, G.*, Zur Kenntniss der Morphologie des inneren Ohres bei Wirbelthieren. Nord. Med. Ark. 1880. Vol. XII, p. 6.

*Retzius, G.*, Ueber die peripherische Endigungsweise der Gehörnerven. Biol. Untersuch. Stockholm and Leipzig, pp. 51–61.

*Schultze, F. E.*, Zur Kenntniss der Endigungsweise der Hörnerven bei Fischen und Amphibien. Arch. f. Anat. u. Physiol. 1862, p. 381.

*Stannius, H.*, Handbuch der Zootomie von v. Siebold und Stannius. Berlin, 1856. 2nd Edit., Pt. II.

*Tafani, A.*, L’organo dell’ udito. Firenze, 1885.

*Waldeyer, W.*, Hörnerv und Schnecke. Stricker’s Handbuch der Gewebelehre, pp. 915–963.

*Weber, E.*, Amtlicher Bericht über die neunzehnte Versammlung deutscher Naturforscher und Aerzte in Braunschweig im Sept. 1841. Printed Braunschweig, 1842.

*Windischmann*, De penitiori auris in amphibiis structura Lipsiae, 1831.

VI. THE EYE.

a. The cornea and sclerotic.

*Angelucci, A.*, Ueber den Bau u. die Entwickelung des vorderen Uvealtractus der Vertebraten. Centralbl. f. d. med. Wiss. 1879. No. 24, p. 417.

*Altmann, R.*, Ueber die Verwerthbarkeit der Corrosion in der mikroskopischen Anatomie. Arch. f. mik. Anat. 1879. Vol. XVI, p. 471 (Corneal corpuscles).

*Arnold, J.*, Die Vorgänge bei der Regeneration epithelialer Gebilde. Virchow’s Arch. 1869. Vol. XLVI, p. 168.

*Arnold, J.*, Experimentale Untersuchungen über die Entwicklung der Blutcapillaren. Virchow’s Arch. 1871. Vol. LIII, p. 70. 1872. Vol. LIV, p. 1.

*Boddaert*, Zur Histologie der Cornea. Centralbl. f. med. Wiss. 1871, p. 337.

*Ciaccio, J. V.*, On the nerves of the cornea and of their distribution in the corneal tissue of man and animals. Trans. Micros. Soc. London, 1863. Vol. XI, p. 77.

*Clasow, E.*, Om corneal epithel. Upsala läkareförenings förhandlingar. 1869. Vol. IV, p. 411.

*Cohnheim, J.*, Ueber die Endigung der sensiblen Nerven in der Hornhaut. Virchow’s Arch. 1867. Vol. XXXVIII, p. 343.

*Durante, F.*, Sulla terminazione dei nervi della cornea. Richerche fatte nel laborat. di anat. normal. Roma, pubbl. dal dott. F. Tocharo. 1873, pp. 81–87.

*Engelmann, T. V.*, Ueber die Hornhaut des Auges. Leipzig, 1867.

*v. Ewetsky*, Ueber das Endothel der Membrana Descemeti. Untersuch. aus d. pathol. Institut. Zürich, 1875. Vol. III.

*Frey, H.*, Handbuch der Histologie und Histochemie.

*Generisch*, Zur Lehre von den Saftkanälchen in der Cornea. Med. Jahrb. der Gesellsch. d. Aerzte in Wien. 1871, p. 1.

*Guye, A. G.*, Over bekercellen en in het byzonder over de bekercellen in de membrana nictitans van den Kïkvonch. Nederl. Tydschrift v. Gewesh. 1868. Vol. II, p. 135.

*Hansen, A.*, Untersuchungen über die entzündlichen Veränderungen der Hornhautkörper. Wiener Med. Jahrb. 1871, p. 210.

*Harpeck, C.*, Ueber die Bedeutung der nach Silberimprägnation auftretenden weissen lücken- und spaltähnlichen Figuren in der Cornea. Arch. f. Anat. u. Physiol. 1864, p. 222.

*Hartmann, R.*, Ueber die durch den Gebrauch der Höllensteinlösung künstlich dargestellten Lymphgefässanhänge, Saftcanälchen und epithelähnlichen Bildungen. Arch. f. Anat. u. Physiol. 1864, p. 235.

*Heiberg, H.*, Ueber die Neubildung des Hornhaut-Epithels. Wiener Med. Jahrb. 1871.

*Heisrath, F.*, Ueber d. Zusammenhang d. vordern Augenkammer mit d. vord. Ciliarvenen. Arch. f. mik. Anat. 1878. Vol. XV, p. 209.

*Helfreich*, Ueber die Nerven der Conjunctiva und Sclera. Würzburg, 1870.

*Henle, J.*, Handbuch der systematischen Anatomie, 1866. Vol. II.

*His, W.*, Untersuchungen über der Bau der Hornhaut, in Verhandlungen der phys.-med. Gesellschaft in Würzburg. 1856. Vol. IV, p. 90.

*His, W.*, Ueber die Einwirkung des salpetersauren Silberoxydes auf die Hornhaut. Schweizerische Zeitsch. f. Heilkunde. 1864. Vol. II, p. 1.

*Hoffmann, F. A.*, Ueber Contractilitätsvorgänge im vorderen Epithel der Froschhornhaut. Diss. Berlin, 1868.

*Hoffmann, F. A.*, Epithelneubildung auf der Cornea. Virchow’s Arch. 1870. Vol. LI, P. 373.

*Hosch, F.*, Ueber die angebliche Contractilität der Knorpelzellen und Hornhaut-körperchen. Pflüger’s Arch. f. d. ges. Physiol. 1873. Vol. VII, p. 515.

*Hoyer, H.*, Ueber den Austritt von Nervenfasern in das Epithel der Hornhaut. Arch. f. Anat. u. Physiol. 1866, pp. 180–195.

*Hoyer, H.*, Ueber die Nerven der Hornhaut. Arch. f. mik. Anat. 1873. Vol. IX, p. 220.

*Klebs, E.*, Das Epithel der hintern Hornhautfläche. Centralbl. f. d. med. Wiss. 1864, p. 513.

*Klein, E.*, Some remarks on the finer nerves of the cornea. Monthly Journ. Micros. Sci. 1872. Vol. VII, pp. 156–164.

*Klein, E.*, Beiträge zur Kenntniss der peripherischen Verzweigung markloser Nervenfasern. Centralbl. f. d. med. Wiss. 1871, p. 594.

*Klemensiewicz, R.*, Karyokinese in den fixen Hornhautzellen bei Entzündung. Centralbl. f. d. med. Wiss. 1884, p. 163.

*v. Kölliker, A.*, Ueber die Nerven der Hornhaut. Mittheilungen der naturforschenden Gesellschaft in Zürich. 1849.

*v. Kölliker, A.*, Ueber die Nervenendigungen in der Hornhaut. Würzb. naturw. Zeitschr. 1866. Vol. VI, p. 121.

*Königstein, L.*, Histologische Notizen. Arch. f. Ophthalmologie. 1881. Vol. XXVII, p. 56.

*Königstein, L.*, Beobachtungen über die Nerven der Cornea und ihre Gefässe. Wiener Sitzungsber. 1877. Vol. LXXVI, Pt. III, p. 17.

*Königstein, L.*, Beobachtungen über die Nerven der Cornea und ihre Gefässe. Wiener Sitzungsber. 1877. Vol. LXXVI, Pt. III, p. 37.

*Krause, W.*, Ueber das vordere Epithel der Cornea. Göttinger Nachrichten, 1870. Arch. f. Anat. u. Physiol. 1870.

*Krause, W.*, Anatomischer Jahresbericht für 1871 in Prager Vierteljahrsschrift.

*Kühne, W.*, Untersuchungen über Protoplasma und die Contractilität. 1864.

*Lavdowsky, M.*, Das Saugadersystem und die Nerven der Cornea. Arch. f. mik. Anat. 1872. Vol. VIII, p. 538.

*Leber, T.*, Zur Kenntniss der Imprägnationsmethoden der Hornhaut und ähnlicher Gewebe. Arch. f. Ophthalmologie. 1867. Vol. XIV, p. 300.

*Leydig, F.*, Lehrbuch der Histologie. 1857.

*Lightbody, W. H.*, Observations on the comparative anatomy of the cornea of vertebrates. Journ. of Anat. and Phys. 1867. Vol. I, p. 15.

*Lipmann, H.*, Ueber die Endigung der Nerven im eigentlichen Gewebe und im hinteren Epithel der Hornhaut des Frosches. Virchow’s Arch. 1869. Vol. XLVIII, p. 218.

*Lott, G.*, Ueber den feineren Bau und die physiologische Regeneration der Epithelien, insbesondere des Cornea-Epithels. Centralbl. f. d. med. Wiss. 1871.

*Moseley, H. N.*, Some remarks on the nerves of the cornea of the rabbit and frog. Quart. Journ. Micros. Sci. 1871. Vol. XI, p. 261.

*Müller, C. F.*, Histologische Untersuchungen über die Cornea. Virchow’s Arch. 1867. Vol. XLI, p. 110.

*v. Recklinghausen, F.*, Notiz über Silberimprägnation. Virchow’s Arch. 1860. Vol. XIX, p. 451.

*v. Recklinghausen, F.*, Die Lymphgefässe und ihre Bedeutung zum Bindegewebe. Berlin, 1862.

*Robinski*, Die Kittsubstanz auf Reaction des Argentum nitricum. Arch. f. Anat. u. Physiol. 1871, p. 184.

*Rollett, A.*, Ueber das Gefüge der Substantia propria corneae. Sitzungsb. Wiener Akad. 1859. Vol. XXXIII, p. 516.

*Rollett, A.*, Ueber die Contractilität der Hornhautkörper und die Hornhauthöhlen. Centralbl. f. d. med. Wiss. 1871, p. 193.

*Rollett, A.*, Ueber die Hornhaut. Stricker’s Gewebelehre. 1872, p. 1091.

*Saemisch, T.*, Beiträge zur normalen und pathologischen Anatomie des Auges (Nerves of Cornea). Leipzig, 1862.

*Sattler, E. E.*, Die Verwendung des Lapisstiftes sur Untersuchung der Epithelien. Arch. f. mik. Anat. 1882. Vol. XXI, p. 672.

*Schalygen, C.*, Ueber Hornhautepithel und besonders über Vermehrung der Zellen desselben. Arch. f. Ophthalmol. 1866. Vol. XII, p. 83.

*Schneider, A.*, Ueber die Vermehrung der Epithelzellen der Hornhaut. Würzb. naturw. Zeitsch. 1862. Vol. III, p. 105.

*Schwalbe, G.*, Ueber ein mit Endothel bekleidetes Höhlensystem zwischen Choroidea und Sclerotica. Central. f. d. med. Wiss. Berlin, 1868. No. 54.

*Schweigger*, Ueber den Bau der Hornhaut. Allg. med. Centralzeitung. Berlin, 1862. No. 4.

*Schweigger-Seidel, F.*, Ueber die Grundsubstanz und die Zellen der Hornhaut des Auges. Berichte d. math.-physik. Classe der Königl. Sächs. Gesellsch. d. Wissenschaft. 1869. Vol. XXI, pp. 305–359.

*Stricker, S.*, Conjunctiva und Sclerotica im Handb. der Lehre von den Geweben des Menschen und der Thiere. 1872, p. 1142.

*Swaen, M. A.*, Des éléments cellulaires et des canaux plastiques dans la cornée de la grenouille. Bulletin de l’Acad. roy. de Belgique. 1876. 2nd Series, Vol. XLII, pp. 144–183.

*Tamamscheff, T.*, Ueber die Membrana Demoursiana. Centralbl. f. d. med. Wiss. Berlin, 1869.

*Waldeyer, W.*, Microscopische Anatomie der Cornea, Sclera, Lider und Conjunctiva, in Handbuch der gesammten Augenheilkunde. 1874.

*Wolff, W.*, Die Nerven der Cornea. Arch. f. mik. Anat. 1882. Vol. XX, p. 373.

*Zielonko, J.*, Ueber die Entwicklung und Proliferation von Epithelien und Endothelien. Arch. f. mik. Anat. 1874. Vol. X, p. 351.

b. The lens, choroid, iris, appendages, anterior and posterior chambers.

*Altmann, R.*, Ueber Corrosion in der Histologie. Centralbl. f. d. med. Wiss. 1878, p. 245.

*Altmann, R.*, Ueber die Verwerthbarkeit der Corrosion in der mikroskopischen Anatomie. Arch. f. mik. Anat. 1879. Vol. XVI, p. 471 (Blood-vessels of the choroid).

*Angelucci, A.*, Ueber den Bau und die Entwickelung des vorderen Uveatractus der Vertebraten. Centralbl. f. d. med. Wiss. 1879, p. 417.

*Arnold*, Die Linse. Handbuch der gesammten Augenheilkunde. 1874.

*Barkau, A.*, Beiträge zur Entwicklungsgeschichte des Auges der Batrachier. Wiener Sitzungsber. 1866. Vol. LIV, Pt. I, pp. 70–75.

*Becker*, Untersuchungen über den Bau der Linse bei dem Menschen und den Wirbelthieren. Arch. f. Ophthalmologie. 1863. Vol. IX, Pt. II, pp. 1–42.

*Biedermann, W.*, Zur Histologie und Physiologie der Schleimsekretion (Membrana nictitans). Wiener Sitzungsber. 1886. Vol. XCIV.

*Born, G.*, Ueber die Nasenhöhlen und den Thränennasengang der Amphibien. Morph. Jahrb. 1875. Vol. II, p. 4.

*Bubuchin*, Die Linse. In Stricker’s Handb. der Gewebelehre. 1872.

*Burow*, De vasis sanguif. ran. Diss. Regiomonti, 1838.

*Ciaccio, C. V.*, Beobachtungen über den inneren Bau des Glaskörpers im Auge des Menschen und der Wirbelthiere im Allgemeinen. Moleschott’s Untersuchungen. 1870. Vol. X, p. 385.

*Faber, C.*, Der Bau der Iris des Menschen und der Wirbelthiere. Leipzig, 1876.

*Frey*, Handbuch der Histologie und Histochemie des Menschen. 1874.

*Fubini, S.*, Beiträge zum Studium der Krystalllinse. Moleschott’s Untersuchungen. 1876. Vol. XI, p. 291.

*Golubew*, Beiträge zur Kenntniss des Baues und der Entwicklungsgeschichte der Capillargefässe des Frosches. Arch. f. mik. Anat. 1869. Vol. V, p. 49.

*Grünhagen*, Ueber das Vorkommen eines Dilatator pupillae in der Iris. Zeitsch. f. rat. Med. Vol. XXVIII, pp. 178, 186.

*Heisrath, F.*, Ueber den Zusammenhang der vorderen Augenkammer mit den vorderen Ciliarvenen. Arch. f. mik. Anat. 1878. Vol. XV, p. 209.

*Henle, J.*, Zur Anatomie der Crystalllinse. Abhandl. Gesells. d. Wiss. zu Göttingen. 1878. Vol. XXIII.

*Henle, J.*, Zur Entwicklungsgeschichte der Krystalllinse und zur Theilung des Zellkerns. Arch. f. mik. Anat. 1882. Vol. XX, p. 413.

*Hirschberg*, Zur Dioptric und Ophthalmologie der Amphibienaugen. Arch. f. Anat. u. Physiol. 1887, p. 493.

*Iwanoff*, Beiträge zur normalen und pathologischen Anatomie des Froschglaskorpers. Centralbl. f. d. med. Wiss. 1868, p. 129.

*Klein, E.*, On the peripheral distribution of non-medullated nerve-fibres (Nerves of the nictitating membrane). Quart. Journ. Micros. Sci. 1872. Vol. XII, pp. 21–32.

*Koganeï, J.*, Untersuchungen über den Bau der Iris des Menschen und der Wirbelthiere. Arch. f. mik. Anat. 1885. Vol. XXV, p. 1.

*Koganeï, J.*, Untersuchungen über den Bau der Iris. Sitzungsber. d. Acad. d. Wiss. Berlin, 1885, p. 105.

*v. Kölliker, A.*, Handbuch der Gewebelehre. 1867.

*Langer, C.*, Ueber das Lymphgefässsystem des Frosches. Wiener Acad. Sitzungsb. 1867. Vol. LV, Pt. I, p. 603.

*Leydig, F.*, Anatomisch-histologische Untersuchungen über Fische und Reptilien, 1853.

*Leydig, F.*, Lehrbuch der Histologie des Menschen und der Thiere. 1857.

*Manz, W.*, Ueber den Mechanismus der Nickhautbewegung beim Frosche. Berichte über d. Verhandl. d. naturforsch. Gesell. Freiburg, 1862. Vol. II, p. 391.

*Moriggia, A.*, Ueber die beste Darstellungsweise und die Entwicklung der Röhrchen der Krystalllinse. Moleschott’s Untersuchungen. 1870. Vol. X, p. 658.

*Openchowski, T.*, Histologisches zur Innervation der Drüsen. Pflüger’s Arch. f. d. ges. Physiol. 1882. Vol. XXVII, pp. 223–232.

*Petit*, Sur l’œil de la grenouille. Mém. de l’académie d. Sciences, 1737; see also Lehrbuch d. vergleich. Anatomie, Stannius, Berlin, 1846, p. 198.

*Robinski, S.*, Zur Anatomie, Physiologie und Pathologie der Augenlinse des Menschen und der Wirbelthiere. Arch. f. Anat. u. Physiol. 1872, p. 178.

*Robinsky, S.*, Die Augenlinsensterne des Menschen und der Wirbelthiere. Centralbl. f. d. med. Wiss. 1877, p. 51.

*Sattler, E. E.*, Die Verwendung des Lapisstiftes zu Untersuchungen der Epithelien. Arch. f. mik. Anat. 1882. Vol. XXI, p. 672.

*Stricker, S.*, Untersuchungen über die capillaren Blutgefässe in der Nickhaut des Frosches. Wiener Sitzungsb. 1865, Vol. LI, Pt. II, pp. 16–27; and Moleschott’s Untersuchungen, 1866, Vol. X, pp. 168–180.

*Stricker, S.*, Untersuchungen über die mechan. Leistungen d. acirrösen Drüsen. Wiener med. Jahrb. 1880, p. 355; also Wiener Sitzungsb. 1880 (Membrana nictitans and skin); also in Moleschott’s Untersuchungen. 1870. Vol. X, p. 237.

*Stricker, S.*, Studien über den Bau und das Leben der capillaren Blutgefässe. Wiener Sitzungsb. 1866. Vol. LII, Pt. II, p. 379.

*Stricker, S.*, Untersuchungen über die capillaren Blutgefässe in der Nickhaut des Frosches. Moleschott’s Untersuchungen. 1870. Vol. X, p. 168.

*Thin, G.*, Contribution to the anatomy of the lens. Journ. of Anat. and Physiol. 1876. Vol. X, p. 223.

*Valentin*, Handbuch der Physiologie v. Wagner. 1842.

*Virchow, H.*, Ueber die Gefässe im Auge und in der Umgebung des Auges beim Frosche. Zeit. f. wiss. Zool. 1881. Vol. XXXV, pp. 247–281.

*Virchow, H.*, Ueber die Gefässe des Kopfes und des Auges des Frosches. Verhandl. Würzburg. 1881. Vol. XV, p. xxxiv.

*Virchow, H.*, Mittheilungen zur vergleichenden Anatomie des Wirbelthierauges. Versamml. deutsch. Naturf. und Aerzte. Strassburg. 1885, pp. 409, 410.

*Virchow, H.*, Ueber den ciliaren Muskel des Frosches. Verhandl. d. physiol. Gesell. zu Berlin. 1885, p. 571.

*Virchow, H.*, Ueber die verschiedenen Formen des Ligamentum pectinatum iridis. Versamml. d. Naturf. und Aerzte. 1885, p. 409.

*Zimmermann, W.*, Ueber circumvasale Safträume der Glaskörpergefässe von Rana esculenta. Arch. f. mik. Anat. 1886. Vol. XXVII, p. 410.

c. The retina.

*Babuchin*, Vergleichende histologische Studien. Würzburger naturwissensch. Zeitsch. 1864. Vol. V, p. 127.

*Beauregard, M. H.*, Contribution à l’étude du rouge rétinien. Journ. de l’anat. et de la physiol. 1879. Vol. XV, p. 161.

*Boll, F.*, Zur Anatomie und Physiologie der Retina. Berlin. Acad. Monatsber. 1876, p. 783.

*Dennissenko, G.*, Vorläufige Bemerkungen zur Lehre über den Bau der Netzhaut. Mitt. aus dem embryolog. Institut. d. Wiener Universität, 1880, Vol. II, p. 1; Abstract in Centralbl. f. d. med. Wiss. 1880, P. 739.

*Dennissenko, G.*, Ueber den Bau der äusseren Körnerschicht der Netzhaut bei den Wirbelthieren. Arch. f. mik. Anat. 1881. Vol. XIX, p. 395.

*Dietl, M. J.*, Beitrag zur Kenntniss des feineren Baues der Stäbchenaussenglieder in der Netzhaut des Frosches. Arch. f. Augen- u. Ohrenheilkunde. 1878. Vol. VII, pp. 17–24.

*Dobrowolsky*, Die Doppelzapfen. Arch. f. Anat. u. Physiol. 1871.

*Dobrowolsky*, Zur Anatomie der Retina. Arch. f. Anat. u. Physiol. 1871.

*Ewart, J. C.*, Notes on the minute structure of the retina and vitreous humour. Journ. of Anat. and Physiol. 1875. Vol. IX.

*Ewart, J. C.*, and *Thin, G.*, On the structure of the retina. Journ. of Anat. and Physiol. 1876. Vol. IX, p. 166.

*Frisch*, Gestalten des Choroidalpigments. Wiener Sitzungsber. 1868. Vol. LVIII, pp. 316–320.

*Heinemann, C.*, Beiträge zur Anatomie der Retina. Arch. f. mik. Anat. 1877. Vol. XIV, p. 409.

*Helfreich*, Ophthalmoscopische Mittheilungen über den Purpur der Retina. Centralbl. f. d. med. Wiss. 1877, p. 113.

*Henle* and *Merkel*, Ueber die sogenannte Bindesubstanz der Centralorgane des Nervensystems. Zeitsch. f. rat. Med. 3rd Series, 1869. Vol. XXXIV.

*Hensen*, Ueber das Sehen in der Fovea centralis. Virchow’s Arch. 1867. Vol. XXXIX, p. 75.

*Hoffmann*, Lehrbuch der Anatomie der Sinnesorgane.

*Hoffmann*, Bronn’s Thierbuch. Leipzig and Heidelberg, 1873–1878. Vol. VI, pp. 274–297.

*Hulke, J. W.*, A contribution to the anatomy of the amphibian and reptilian retina. Quart. Journ. Micros. Sci. 1864, Vol. IV, p. 236; and London Ophthalmic Hospital Reports, 1864.

*Hulke, J. W.*, On the retina of amphibia and reptiles. Journ. of Anat. and Physiol. 1867. Vol. I, p. 94.

*Kühne, W.*, Ueber den Sehpurpur. Centralbl. f. d. med. Wiss. 1877, p. 193.

*Kühne, W.*, Fortgesetzte Untersuchungen über die Retina und die Pigmente des Auges. Heidelberger physiol. Untersuch. 1878, Vol. II, p. 89; Abstract in Centralbl. f. d. med. Wiss. 1879, p. 276.

*v. Kölliker, A.*, Zur Anatomie und Physiologie der Retina. Verhandl. d. phys.-med. Gesellsch. Würzburg, 1852. Vol. III, p. 316.

*v. Kölliker, A.*, Microscopische Anatomie. 1854. Vol. II.

*v. Kölliker, A.*, Handbuch der Gewebelehre. 1867.

*Krause, W.*, Die Nervenendigung in der Retina. Arch. f. mik. Anat. 1876. Vol. XII, pp. 742–790.

*Krause, W.*, Die Nervenendigung innerhalb der terminalen Körperchen. Arch. f. mik. Anat. 1881. Vol. XIX, p. 53.

*Landolt*, Beitrag zur Anatomie der Retina vom Frosch, Salamander und Triton. Arch. f. mik. Anat. 1871. Vol. VII, p. 81.

*Leydig, F.*, Anatomisch-histologische Untersuchungen über Fische und Reptilien. 1853.

*Leydig, F.*, Die Farbe der Retina und das Leuchten der Augen. Arch. f. Naturgesch. 1877. Vol. XXXIII, p. 8.

*Manz, W.*, Ueber den Bau der Retina des Frosches. Zeitsch. f. rat. Med. 3rd Series, 1861. Vol. X, pp. 301–322.

*Manz, W.*, Die Ganglienzellen der Froschnetzhaut. Zeitsch. f. rat. Med. 3rd Series, 1866. Vol. XXVIII.

*Merkel*, Zur Kenntniss der Stäbchenschicht der Retina. Arch. f. Anat. u. Physiol. 1870, p. 642.

*Morano, F.*, Die Pigmentschicht der Retina. Arch. f. mik. Anat. 1872. Vol. VIII, p. 81.

*Morano, F.*, Stomata in der Pigmentschicht der Retina. Centralbl. f. d. med. Wiss. 1875, p. 67.

*Müller, H.*, Histologie der Netzhaut. Zeitsch. f. wiss. Zool. 1851–52. Vol. III, p. 234.

*Müller, H.*, Ueber sternförmige Zellen der Retina. Würzb. Verhandl. 1852. Vol. II, pp. 216–218.

*Müller, H.*, Ueber einige Verhältnisse der Netzhaut bei Menschen und Thieren. Würzb. Verhandl. 1853. Vol. IV, p. 96.

*Müller, H.*, and Kölliker, A., Retina-Tafel. Plate XIX in Ecker’s Icones Physiol. Leipzig, 1854.

*Müller, H.*, Observations sur la structure de la rétine de certains animaux. Compt. rend. 1856, Vol. XLIII, p. 743; and Annales hist. nat. 1856, Vol. XVIII, p. 492.

*Müller, H.*, Anatomisch-physiologische Untersuchungen über die Retina des Menschen und der Wirbelthiere. Zeitsch. f. wiss. Zool. 1857. Vol. VIII, p. 27.

*Müller, W.*, Ueber die Stammentwicklung des Sehorgans der Wirbelthiere. Leipzig, 1874, Festgabe an Carl Ludwig; Abstract in Centralbl. f. d. med. Wiss. 1877, pp. 372 and 388.

*Ogneff, J.*, Histogenese der Retina. Centralbl. f. d. med. Wiss. 1881, p. 641.

*Ogneff, J.*, Ueber die moleculäre Schicht und die sogenannte reticuläre Substanz der Retina. Centralbl. f. d. med. Wiss. 1883, p. 801.

*Oppenheimer, L. S.*, Die Stäbchen in der Netzhaut der Froschembryonen. Schenk’s Embryol. Mitt. Wien. 1878, p. 163.

*Ranvier, L.*, Traité technique d’histologie, sixième fasicule. 1882.

*Ritter*, Ueber den Bau der Stäbchen und äusseren Endigungen der Radialfasern an der Netzhaut des Frosches. Arch. f. Ophthalmol. 1859.

*Ritter*, Zur Histologie des Auges. Arch. f. Ophthalmol. 1868. Vol. XI.

*Schifferdecker*, Studien zur vergleichenden Histologie der Retina. Arch. f. mik. Anat. 1886. Vol. XXVIII, p. 305.

*Schultze, M.*, Zur Anatomie und Physiologie der Retina. Arch. f. mik. Anat. 1866. Vol. II, pp. 175–286.

*Schultze, M.*, Ueber Stäbchen und Zapfen der Retina. Arch. f. mik. Anat. 1867. Vol. III, p. 215.

*Schultze, M.*, Bemerkungen zu dem Aufsatze des Dr. W. Steinlin. Arch. f. mik. Anat. 1868. Vol. IV, pp. 10–21.

*Schultze, M.*, Die Retina. Stricker’s Handbuch der Gewebelehre. 1871.

*Schultze, M.*, Ueber die Nervenendigung in der Netzhaut des Auges bei Menschen und bei Thieren. Arch. f. mik. Anat. 1869. Vol. V, p. 380.

*Schwalbe*, Lehrbuch der Anatomie der Sinnesorgane. Erlangen, 1885, p. 392, etc.

*Steinlin, W.*, Zur Anatomie und Physiologie der Retina. Arch. f. mik. Anat. 1868. Vol. IV, p. 10.

THE SKIN AND THE SENSE-ORGANS.

I. THE SKIN AND ITS APPENDAGES.

The general characters and the colouring of the skin have already been described (pp. 4 to 7). The skin consists of the cutis vera or corium, and the cuticle or epidermis, and is possessed of numerous glands.

*a.* The *epidermis* (Figs. 228, 230) consists of several layers of epithelial cells, those of the deepest layer being more or less columnar in form, those of the middle layer shorter and polygonal, while those of the superficial layer are flattened, very transparent, and horny.

All the surfaces of these cells are serrated, the serrations being, however, with difficulty seen on the free surface of the superficial cells (Leydig). Each cell has a distinct nucleus; in the deeper cells the nucleus is oval, broad, and rounded, in the superficial cells flattened and thin.

The surface of the epidermis (Fig. 230) forms a very beautiful mosaic of flat cells, chiefly hexagonal in form, with pale, central, oval nuclei. Here and there two adjacent cells appear to enclose a semilunar space (Fig. 228 D); these spaces are occupied by peculiar cells (goblet-cells, E. Schultze; mucous cells, Leydig), which do not belong to the superficial cells but the layer of cells immediately beneath the horny layer (Schultze, Pfitzner). The cells are rounded or flask-shaped, and closely resemble the epithelial goblet-cells or chalice-cells. According to Rudneff they open on the free surface by stomata; this is, however, denied by Schultze and others.

Vertical section through the epidermis from the head of Rana esculenta; after F. E. Schultze. Magnified 600 times.

A Horny layer. B Middle layer. C Deep layer. D Isolated mucous-cells. ]

Vertical section through the skin of the back; after Wiedersheim.

Co Superficial layer of cutis. Co^1 Middle layer of cutis. Co^2 Deep layer of cutis. D Cutaneous glands. D^1 Ducts of cutaneous glands. Ep Epidermis. H Horny layer of epidermis. P Pigment-cells. W Papillae. ]

According to Pfitzner these cells secrete a substance, which has an important function in connection with the process of casting the skin, which consists in the separation of the upper layer from that below brings about a complete shedding of the skin (Wiedersheim).

Surface view of epidermis of Rana temporaria; after Eberth.

A Epidermal cell. B Stoma-cell. C Attached cuticle from duct of gland. D Protoplasm and nucleus of stoma-cell. ]

Nerve terminations in the branched pigment-cells of the cutis; after Ehrmann. Hartnack, Obj. 8, Oc. 3.

I. Pigment ceasing abruptly at junction of nerve.

II. Pigment gradually ceasing along the nerve. ]

Deeply pigmented, branched cells, capable of contractile movements, are also found, somewhat sparsely distributed, in the epidermis (Leydig, H. Müller, Schultze).]

*b.* The *cutis* (Fig. 229, Co, Co^1, Co^2). The epidermis is generally attached to the corium by means of a continuous layer of branched cells, which is deeply stained when the animals are fed with madder (Katschenko). Many of these cells are pigmented. This layer is seldom flat, but is raised into papillae and folds, which are repeated by the superimposed epidermis. In addition to this layer the corium has, except in the webs and supplemental toes, three distinct layers of connective-tissue, together with much unstriped muscle-fibre (Eberth).

The *superficial layer* (Fig. 229 Co) is a loosely-meshed, much pigmented, vascular layer; it forms a loose support for the numerous glands, and is traversed by numerous nerves.

The *middle layer* (Co^1) forms the groundwork of the cutis; it is much firmer and more compact than the superficial layer; in section it appears as a broad band, bounded superficially by a sharp line. It is chiefly composed of closely packed connective-tissue fibres, which have, for the main part, a horizontal or wavy course; at certain points, however, vertical fibres are seen passing towards the surface and hiding the sharp contour (between Co and Co^1). At such points the two sets of fibres form a sort of basket-work arrangement.

The *deepest layer* (Fig. 229 Co^2) is composed of very delicate, white and yellow elastic fibres, and vessels and nerves; it attaches the whole integument to the underlying organs. By the looseness of its structure it forms an important lymph-space.

The *pigment* of the skin. As already mentioned pigmented cells occur in the epidermis, but by far the greater quantity of the cutaneous pigment is found in the cutis, and more especially in the loose layer of branched cells, which form the boundary between epidermis and true cutis. These cells, known as chromatophore-cells, have been carefully investigated by Harless. They play an extremely important part in bringing about the well-known changes in the colouring of the skin. Bimmerman has proved that these cells are influenced by stimulation of the nerves supplying the region in which they occur. Ehrmann has been able to trace a direct connection between the nerve-fibres and the pigment-cells (Fig. 231 I, II). In such cases the pigment was sometimes sharply marked off, at others was gradually lost along the nerve.]

*c.* The *papillae* and *ridges* of the skin are classified by Leydig as follows: (1) Small ridges, (2) larger ridges, (3) papillae with touch-bodies, (4) papillae without touch-bodies, (5) papillae with the ducts of glands, (6) capillaries in the form of papillae, (7) small elevations, including the lateral organs.

Peculiar wart-like papillae are found on the articulations of the first phalanges with the metatarsus, on the same articulations and on the articulations between the first and second phalanges of the third and fifth toes, and on the articulations between the first, second, and third phalanges of the fourth toe. These papillae are connected with the long flexor tendons by fine tendinous bands (Klein).

*Temporary papillae* are developed in the females of Rana temporaria during the breeding season; according to O. Huber (l. c.), who has described them, their distribution and structure is as follows:--

During the breeding season the skin of the sides of the trunk of female specimens of Rana temporaria is rough; the small elevations, to which this roughness is due, are each about the size of the head of a pin, and have the appearance of small, rounded, white or pale rose-coloured, warty growths. The papillae reach their greatest development and are most numerous on the sides of the trunk (Fig. 232 I); they may be traced on to the tympanic membrane, where they are arranged in a ring, and in some cases under the eyes to the sides of the snout.

Anteriorly the papillae are absent from the median portion of the dorsal surface of the trunk, but posteriorly, behind a line joining the anterior extremities of the two iliac bones, the papillae cover the whole surface.

The papillae are large and very numerous around the arms, and pass by gradual, transitionary stages into the ordinary papillae of the region. Further they may be traced backwards along the anterior or extensor surface of the thigh, the upper surface of the leg, foot, and fifth toe. Occasionally a few papillae were found on flexor surfaces of the third and fourth metatarsus, and very rarely were any discovered on the fore-limbs. They occur in no other batrachian of Germany (Huber).

I. Diagram to show the distribution of the temporary papillae in Rana temporaria; after Huber.

II, III. Vertical sections through a temporary papilla; after Huber. ]

Each papilla (Fig. 232 II and III) consists of a hemispherical elevation of the cutis, and is covered either by a layer of normal epidermis or in some very rare cases the epidermis was slightly thickened. The papilla consists of a firm connective-tissue stroma, and is from 0.2–0.4 mm. in height, 0.4–0.5 mm. broad (after hardening in alcohol). Such glands as exist in the papilla usually open laterally (Fig. 232 III), and the blood-vessels are numerous.

The epidermis covering the papilla is well supplied with nerve-fibres, derived from large ganglion-cells in the papilla (Fig. 232 III). The branched pigment-cells, so numerous in the rest of the skin, are absent from the upper parts of the papillae (Fig. 232 II); the pigment-cells may cease either abruptly or gradually.

The rose-colour of the papillae is due to the presence of a golden red pigment. After the breeding season the papillae are gradually lost, and the pigment-cells wander into the unoccupied parts.

Huber compares the arrangement of the nerves to that of the ‘touch-spots’ of Merkel.

d. The *glands* of the skin are of two kinds, serous and mucous; they have been fully described by Engelmann and Openchowski.

(1) The *serous glands* (Körnerdrüsen, Engelmann) are large, averaging in diameter 0.2–0.4 mm., but others vary in size from 0.13–0.8 mm. in diameter. They are found chiefly on the dorsum of the trunk and arranged in groups, which vary in dimensions from 3–20 mm. in length and 2–4 mm. in breadth. They may be found in any part between the ear-region and the anus, on the dorsal surface of the thigh, especially towards the outer and inner borders. They are found very sparsely distributed on the ventral surface of the trunk and on other parts of the extremities, though as a rule a few are found on the dorsal surface of the feet and near the phalanges. They are wanting in the nictitating membrane.

The glands have a rounded form, with the ducts placed at their superficial poles. The glands possess three coats; externally is a coat of connective-tissue, the fibres of which are arranged closely together, and cross one another at acute angles: these fibres are continuous with the connective-tissue of the surrounding cutis. Inside this coat is a thick layer of muscle-fibre (0.005–0.015 mm.); the muscle-cells are arranged meridionally, with the one pole towards the superficial surface of the gland, the other pole at the deep surface (Hensche). Many of the fibres, however, extend only one-fourth or one-third of this distance.

The innermost coat is a simple layer of epithelial cells, which rests directly on the muscle-layer; no basement-membrane or space of any kind having been discovered between the two layers. When examined in the recent state these cells are conical or cylindrical in shape, and have the appearance of goblet-cells: they possess a delicate but distinct cell-wall, but are open towards the lumen of the gland. One or sometimes two rounded nuclei are found towards the base of the gland, and surrounded by a small amount of granular protoplasm; the rest of the cell is occupied by a mass of small, rounded, highly refractive granules of about 0.002–0.01 mm. in diameter. These granules are also to be found in the protoplasm of the cell; they contain a substance capable of swelling freely, and present many points of resemblance to the granules found in the cells of the oviducts.

These glands represent the poison-glands or lateral glands of toads, and the ear-glands or parotids of Caecilia (Leydig). According to Leroux, Gratiolet and Cloëz, the reaction of these glands in toads varies; according to du Bois-Reymond the reaction is, in frogs, acid; Engelmann found the reaction of these glands, in frogs, to be neutral, frequently, however, with a tendency to either acidity or alkalinity.

These glands correspond with the ‘large glands’ of Hensche, the ‘contractile glands’ of Stieda, the ‘large, dark glands’ of Eberth, and the ‘large contractile glands’ of Leydig’s earlier publications.

(2) The *mucous glands* are, as a rule, smaller, more numerous, and more evenly distributed than the serous glands. Usually they lie in such close proximity as almost to touch one another; according to Engelmann an average number of sixty is found in one square millimeter; on the abdomen 62–68; flexor surfaces of the posterior extremities in some places 76, but in others only 30–40; on the webs only 2–6 to the square millimeter. On the nictitating membrane they are arranged in two or three parallel rows, are large, and closely applied to each other. They are wanting on the deeper surface of the nictitating membrane.

The glands are generally rounded in form and have a short neck (Fig. 229). Glands in the recent condition, and not fully contracted, have a diameter of 0.06–0.21 mm., the majority measure 0.12–0.16 mm. in diameter. The upper pole of the gland is usually placed directly under the boundary between epidermis and cutis, and, as a rule, about 0.06–0.1 mm. beneath the superficial surface of the skin. The duct usually passes directly to the surface, in a straight line.

The structure of the glands corresponds, in general, with that of the serous glands. Externally is a coat of connective-tissue, which is, however, more firmly attached to the muscular coat than in the case of the serous glands, and may easily be mistaken for a structureless basement-membrane (Eberth). The muscular coat is very thin, and consists of 16–20 flat, spindle-shaped fibres; extending from the upper to the lower pole as in the serous glands. At a short distance (0.015–0.022 mm.) from the upper or superficial pole each fibre has an ellipsoid thickening, composed of granular protoplasm, and containing a clear oval nucleus.

The inner coat is composed of a single layer of epithelium, placed directly on the muscular coat. The epithelium has a thickness of about 0.01–0.02 mm.; it is, however, usually thicker towards the base than towards the duct. The boundaries between the cells are very indistinct, and so give the epithelium the appearance of a continuous layer of protoplasm. The glandular epithelium is not directly continuous with the epithelium of the duct.

The shape of the cells depends upon their physiological condition. In a state of semi-contraction of the gland, the cells are cubical, and their free borders pushed into the lumen in a slight convexity; when the gland is fully distended the cells are two or three times as broad as deep; in a fully contracted gland the cells are conical or cylindrical. In the first-mentioned condition their diameter varies from 0.006–0.018 mm. The larger glands are estimated to possess about 150 cells, the smaller only thirty to forty (Engelmann).

The cells appear to have no cell-wall, certainly they possess none on their free surfaces. Their protoplasm distends very freely on the addition of water. As a rule some cells are much more granular than others of the same gland; each cell has a rounded oval, clear nucleus, and vacuoles are frequently met with.

The lumen of the gland contains a colourless, transparent, watery fluid, which contains mucous material.

The ducts of the glands are thick-walled cylinders, circular in section. Their diameter varies from 0.02–0.05 mm., their length is equal to the depth of the superimposed epidermis. The wall of the duct is lined with two or three concentric layers of highly refractive, nucleated cells. The cells are arranged parallel to the length of the duct: in transverse section they are sickle-shaped or semilunar. In the upper third or fourth of the duct the inner wall is lined with a cuticle, very resistant to the action of acids or alkalies: it is thrown off with the skin in the process of casting. In the horny layer of the epidermis this cuticle is partially closed by a stoma-cell (Eberth), (Fig. 230), which possesses a tri-radiate opening.

The glands correspond with the ‘non-contractile glands’ of Hensche, the ‘dark and bright glands’ of Stieda, the ‘glandule mezzane, piccole e piccolissime (ad epitelio pavimentoso)’ of Ciaccio, and the ‘small, dark, and medium-sized, bright glands’ of Eberth.

*e.* The *peculiarities* of the *skin* of the *supplemental toe* and *webs*. The supplemental toe presents, in the male, a rounded, oval swelling (Fig. 234 I, D), with the end of the digit projecting from the distal end.

Normally this swelling is usually of a grey colour; during the breeding season, however, the swelling enlarges, and becomes of a black or deep brown colour (Leydig).

Vertical section through the epidermis of the supplemental toe of Rana esculenta; after E. Schultze. Magnified 400 times. ]

The epidermis covering this swelling (Fig. 233) is much thickened and produced into projecting papillae. The cutis also shows a marked thickening and an increase in vascularity; the glands are of the kind described as mucous glands (Engelmann). They present, however, an immense increase in size, and at the same time are so closely applied to one another as to form the main part of the enlargement (see also Organs of Tactile Sensation).

Fore-foot of a male frog.

D Glandular swelling on the supplemental toe. W Warty papillae on the inter-phalangeal joints.

II.

Vertical section through the swelling on the supplemental toe of a male frog.

B Blood-vessels. Co Cutis. D Glands. Ep Epidermis. M Muscles. P Pigment-cells. ]

In the *webs* the various layers of the corium are more or less fused together, and cannot be distinguished from each other; the glands are, as a rule, smaller than on the general surface of the skin.

*f.* The *blood-vessels* and *lymphatics* of the skin.

(1) The *blood-vessels* of the skin are arranged in two networks; the one is situated immediately beneath the epidermis, and consists of fine capillaries, forming a fine-meshed network, which enclose the ducts of the glands. The meshes vary considerably in size and shape (Hyrtl and Langer). The second network of vessels is situated under the cutis; the vessels forming it are small, and the meshes formed are large. From this network vertical branches pass to form the superficial network; these branches usually course along the strands of vertical fibres already described, and break up to form capillaries only when they reach the deeper surface of the epidermis (Langer), (Fig. 235 I).

The blood-vessels and lymphatics of the skin; after Langer. Arteries striped, lymphatics shaded.

I. Vertical section through skin of thigh. II. Horizontal view of arteries and lymphatics of the skin. III. Peculiar tortuous arteries of the lamina inguinalis. IV. Arteries and lymphatics of the web. ]

In some situations, however, the vertical branches divide earlier; this is especially the case in parts where the glands are very closely packed, as in the nictitating membrane, the upper lip, and the swelling of the supplemental toe (in the male). In these parts the division takes place at the deeper surface of the glands (Langer).

A peculiar arrangement of the cutaneous blood-vessels is found in the lamina inguinalis, where a chain of reddish points can be made out with the naked eye; examined more carefully (Fig. 235 III) each reddish point is found to be a complex loop of capillaries. They extend from the skin to the hinder lymph-hearts, where they form a close network which partially invests the lymph-hearts (Langer).

(2) The *lymphatics of the skin* (see also p. 252), like the arteries, reach the deeper surface of the epidermis by coursing along the bands of vertical fibres; they then form a network of capillaries with rounded meshes (Fig. 235 I, II, IV), and lying immediately under the epidermis, and a network which surrounds the various glands. The lymphatic-capillaries are as a rule larger than the blood-capillaries. The lymphatic network lies beneath the blood network, and the vessels of the two systems branch independently (Langer).

In those parts where the glands are placed closely together this arrangement is modified, and corresponds with the modifications found in the blood-capillaries in these regions. The vertical branches divide so as to form a network below the glands, and from this vertical branches pass in the same direction between the glands to form a secondary network on the superficial surface of the glands (Langer).

g. The *nerves* of the skin. The cutis is very richly supplied with both medullated and non-medullated nerves. In the subcutaneous tissue the nerves destined for the skin branch freely to form numerous fine twigs, which, without actually inosculating, form a fine meshwork. From the larger trunks numerous vertical branches pass vertically to form a secondary network, from which both coarse and very fine twigs pass to encircle the glands. The fine fibres which supply the glands are non-medullated and possess oval nuclei; their diameter varies from 0·001–0·002 mm. The number of nerve-fibres is not much smaller than that of the muscle-fibres (Engelmann). (See also Organs of Tactile Sensation.)]

II. THE ORGANS OF TACTILE SENSATION.

The organs of tactile sensation are the nerve-plexus of the epidermis, the touch-spots of Merkel, the lateral sense-organs, and the touch-corpuscles of the tendons.

*a.* [The *nerve-plexus* of the epithelium is very incomplete as compared with the plexus found in the epithelium of the cornea; here and there a few non-medullated fibres have been traced a short distance between the epithelial cells. No such mode of nerve-terminations in the epithelium as is described by Eberth and Macullum in the tadpole can be found in the adult.]

*b.* The *touch-spots*. What knowledge we possess of these organs is due to the labours of Leydig, Ciaccio, Eberth, and more particularly those of Merkel.

At the base of each papilla, which contains such a touch-organ, is found a number of colourless, flattened cells, arranged either in a single layer, or heaped up and connected with very fine nerve-fibres. The flat surface of the cells is parallel to the surface of the body, and they do not form a separate or circumscribed body, they are therefore better spoken of as touch-spots than as true touch-bodies (Merkel). The larger organs are found in the papillae, but smaller ones may be found on any part of the skin.

I. Lateral sense-organ of tadpole of frog. Half-schematic.

c Central zone (nerve-epithelium). Ml Membrana limitans. p Peripheral zone (sustentacular cells). R Hyaline tube.

II. Touch-corpuscle from the sheath of a digital tendon of the frog; after Löwe. Schieck, Oc. O., Obj. 9. ]

These organs are best seen in the prominence or swelling upon the supplemental toe during the breeding season; they are numerous on the dorsal surface of the trunk, but occur most frequently on the under surface of the hinder feet (Planta pedis). After the breeding season the organs of the thumb undergo a retrogressive change, which results in a network of spindle-shaped and branched cells with fibres (Wiedersheim).

*c.* The *lateral sense-organs* attain their highest development in the tadpole; in the adult the organs have undergone a retrogressive change, the result of which is that the organs are diminished in size; the whole organ sinks by the formation of a tube, which is then closed by a mucous secretion, consequently the organ is functionless: with this loss in function and change in position of the organs a corresponding diminution of the ramus lateralis nervi vagi occurs (Merkel).

Each lateral organ (Fig. 236 I) consists of a slightly elevated papilla, with the centre depressed, and in each may be distinguished a central and a peripheral zone (c, p). The central zone consists of a group of pear-shaped cells, with the narrower ends directed towards the free surface; each is connected below with a nerve-fibril, while above it bears a short, stiff cilium. The cilia are enclosed in a delicate hyaline tube (R), which is open superficially, closed by the papilla below; consequently the cilia are in direct contact with the surrounding medium. The peripheral zone is a layer of pale, flattened, cylindrical cells (p); they possess, at their upper borders, a perforated membrana limitans (Ml), through which the cilia pass. These cells serve as a support to the central cells, and are themselves surrounded by ordinary epithelial cells.

The distribution and arrangement of the lateral organs is alike in fish and larval amphibia. They are most numerous on the head, where they surround the eye, and are continued forwards to the snout and on to the lower jaw. All these organs on the head are in connection with the trigeminal nerve. A line of these organs passes from the hinder part of the circumference of the eye along the gill-cover to the neck, where the lines of opposite sides are usually, though not constantly, joined by a transverse line of the same organs; thence the lines are continued along the trunk to the tip of the tail. In fish there exists, as a rule, only one pair of such longitudinal lines (Linea lateralis); in anura-larvae, proteus, and in all salamanders there are three pairs: of these one pair lies near the vertebral column, the second at the junction of the flank with the abdomen, and the third corresponds to the lateral line in fish (Malbranc).

At an early developmental period each metamere possesses one pair of such lateral organs; in later life, however, this simple arrangement is lost, and each segment usually possesses a group of organs.

The organs of the trunk and tail are supplied by branches of the Ramus lateralis nervi vagi. Both in fish and amphibia a reparative process, by means of fission, occurs; as a consequence the organs are found in various stages of development.

*d.* [The *touch-corpuscles* of Golgi and Löwe (Fig. 236 II) are found on the joints of the digits. They are surrounded by connective-tissue and are spindle-shaped; the two ends of the spindle are glassy in appearance, the middle portion is fibrous. In the thickest part of the corpuscle is a zone of nuclear bodies.

They are regarded as touch-bodies (Golgi and Löwe). Golgi (l. c.) describes two kinds of touch-organs in connection with muscle and tendon; one class correspond with those just described, he names them ‘nervous muscle-tendon organs.’ The second class he compares with the touch-bodies found in the conjunctiva.]

III. THE ORGANS OF TASTE.

The organs of taste are not confined to the surface of the tongue, but are also found on the mucous membrane of the roof of the mouth, especially in the neighbourhood of the vomerine teeth; on both roof and floor of the mouth these organs can be traced to the commencement of the oesophagus.

*a.* The *filiform papillae* are the more numerous; they are conical or thread-like in form, and consist of connective-tissue, with a few striated muscle-fibres; they include blood-capillaries, but no nerves have been traced into them (Leydig). They are covered with ciliated epithelium and goblet-cells.

*b.* The *fungiform papillae* are much larger, and are paler than the filiform papillae. The free ends of these papillae are broader than the bases, and when the epithelium is removed the free ends present a concavity. From the base to the border of the free surface each papilla is covered with the usual oval, ciliated epithelium, but at this border an abrupt transition takes place. The epithelium covering the end of the papillae is of three kinds: goblet-cells, cylindrical cells, and forked cells; the three forms of cells are quite characteristic, and no intermediate transitionary forms are met with.

(1) The *goblet-cells* (Fig. 237 I) are arranged vertically to the free surface of the papilla; they are from 0.020–0.024 mm. in length, and from 0.01–0.02 mm. in diameter. In the lower third of the cell is found a nucleus of about 0.008 mm. in diameter, and this encloses a nucleolus of about 0.001 mm. in diameter. Close underneath the nucleus the cell is contracted to form an irregular process or foot. The contents of the cells are a very finely granular, transparent protoplasm. These cells form the outermost part of the epithelium, covering the end of the papilla; all the cells belonging to the same papilla are of the same size. In consequence of the mutual pressure which they exert on each other they present, in transverse section, six-sided outlines (Fig. 237, 2). The nuclei of adjacent cells are placed at almost exactly the same level. By the action of reagents on these cells very remarkable forms are obtained, in consequence of the protoplasm swelling and being forced upwards (Fig. 237, 5).

I. Various parts from the fungiform papillae; after Engelmann.

1. Nerves of a fungiform papilla. Magnified 450 times.

2. Surface view of the epithelium, after five minute’s action of iodized serum. Magnified 600 times.

3. Goblet-cell with adjacent forked cell. Magnified 450 times.

4. Portion of the papilla, after removal of the goblet- and forked cells; only cylindrical cells remaining. Magnified 400 times.

5. Goblet-cell, with swollen contents. Magnified 450 times.

6–13. Various forms of isolated forked cells. Magnified 450 times.

II. Sections of two glands of the tongue; after Biederman.

1. Resting-gland. 2. Gland after stimulation. ]

(2) The *cylindrical cells* (Fig. 237 I) have rounded free extremities, which reach to the general surface of the epithelium; the remainder of the cell is cylindrical except towards its lower extremity, where it is slightly dilated and encloses an oval nucleus: the protoplasm of the cells is very finely granular. These cells rest on the connective-tissue of the papilla, and are in close juxtaposition, so that several hundreds of them are found on one papilla.

The spaces between the upper parts of the cylindrical cells are occupied by the goblet-cells and by the forked cells.

(3) The *third form* of cell found on the fungiform papillae are named *forked cells* (Fig. 237 I) by Engelmann. The body of the cells has an ellipsoidal form, is from 0.006–0.008 mm. in its longer diameter, and 0.003–0.004 mm. in the shorter diameter. Processes arise from both poles. The peripheral processes arise by a short common stem, which then divides into two or rarely three branches; the whole process is from 0.004–0.008 mm. in length, and is always just sufficiently long to reach the general surface of the epithelium: when the peripheral process is long the central is usually shorter, and vice versâ.

The central processes arise by a stem from 0.001–0.002 mm. in thickness, which usually divides dichotomously. The length of this process may be as much as 0.025 mm. or almost nil.

The forked cells are about twice as numerous as the goblet-cells, they occupy the spaces between the cylindrical cells and the goblet-cells. The branched central processes form a network on the connective-tissue of the papilla, which is, at this point, perforated by a rich plexus of fine non-medullated nerve-fibrils. It is not decided whether the processes of various cells inosculate. Engelmann regards these forked cells as the taste-cells and as the sensory nerve-endings.

The *bodies* of the fungiform papillae contain blood-vessels and nerves, the latter enter as medullated nerves, but lose the medulla, somewhat abruptly towards the upper end of the papilla, where they form a sort of nerve-cushion (Nervenkissen, Engelmann).]

Taste-organs are also found on the roof and other parts of the mouth, and present many points of resemblance to the lateral sense-organs. Like them they present a peripheral zone and a central zone; the cells of the latter, however, are not longer than the peripheral cells, and possess no cilia (J. van der Hoeven, Merkel).

IV. THE NOSE.

The *anterior nares* or nostrils are two small openings, placed directly in front of the anterior angle of the eye; the distance between the eye and the corresponding nostril being, in the case of adult animals, about five or six millimeters. The anterior nares are surrounded by rims, which are contracted below, and so form very short, tentacular-like prominences.

The *posterior nares* (choanae) are about four millimeters from the anterior nares, consequently the long axis of the nose is, approximately, of this length. (For the external muscles of the nose, see p. 59.)

The *boundaries* of the *nasal cavities* are as follows:--the roof of each cavity is formed by the dorsal plate of the sphenethmoid, the nasal bone, and the premaxillary bone; the floor is formed by the vomer and the palatine bone, the inner wall by the vertical septum of the sphenethmoid, the outer wall by the premaxillary and maxillary bones, the anterior wall by the premaxillary bone, and the posterior wall by the sphenethmoid. The cartilaginous portion of the nasal skeleton (see also p. 27) projects into the general cavity and subdivides it into various sinuses, which have been the subject of careful investigation by Born and Wiedersheim.

*a.* The *nasal cavities* are best examined by means of serial transverse sections; in a section through the anterior nares (Figs. 238, 239) there will be seen three sinuses on either side:--

(1) The *superior sinus* (on) is large, rounded, and placed against the cartilaginous septum; the sinus is lined with olfactory epithelium. Posteriorly the sinus extends beyond the posterior nares, and is bounded by the anterior surface of the sphenethmoid. In front it ends in a rounded concavity, likewise lined with olfactory mucous membrane. Opposite the anterior nares the cavity is partially subdivided, by a longitudinal process on the floor, into two cavities; the anterior nares open into the external chambers, and therefore not directly into the main cavity of the superior sinus. The superior sinus communicates with the inferior sinus by a narrow, almost vertical, slit.

(2) The *inferior sinus* (un) is narrow and flattened from above downwards; it is placed against the maxillary bone, and represents the maxillary sinus of the frog. Externally it possesses a descending arm.

The inferior sinus is continued backwards and opens on its inner side into the posterior nares, or rather into the mouth. The descending arm extends only a short distance forwards, to terminate near the point where the superior and inferior sinuses communicate by only a narrow opening. This sinus is on the whole broader in front than behind, and has a general direction from without, inwards and forwards underneath the superior sinus.

Frontal sections through the nose of two tadpoles; after G. Born.

A Anterior naris. b Cartilaginous floor. C Cutis. d Cartilaginous roof. Ep Epidermis. gi Intermaxillary gland. gni Lower nasal gland. gns Upper nasal gland. K Maxillary sinus. l Concha narium (os lachrymale). m Maxillary bone. MS Oral mucous membrane. ok Cartilage. on Upper blind sac. R Pharyngeal gland. S Nasal septum. se Septum between the upper and lower nasal cavity. sn External blind sac. T Trabeculae. Th Lachrymal duct. un Lower blind sac. ]

(3) The *lateral sinus* (sn) is situated in the partition between the superior and inferior sinuses, or rather between the external chamber of the upper sinus and the inferior sinus. The lateral sinus is triangular in form, being narrow in front and broad behind; at its inner posterior angle it opens on the free border of the horizontal partition between the superior and inferior sinuses; this opening is, however, continued along its roof, so that the lateral sinus opens also into the superior sinus.

*b.* The *nasal cartilages*. The two nasal cavities are completely separated by the cartilaginous septum (Figs. 238 and 239 S), and are for the most part lined by cartilage. The anterior end is formed of concave cartilages, while the posterior, being situated in the sphenethmoid, is usually more or less ossified in the adult. The posterior wall has two openings: a larger near the septum for the olfactory nerve, and a smaller, more externally, for the nasal branch of the trigeminal nerve.

The anterior wall is more complex than the posterior, being thicker in the middle than at the sides, and possessing three blind sacs for the three sinuses. From the anterior wall two processes project backwards between the sacs and enclose them more or less completely.

Of the three sacs or cavities only the lower is completely surrounded by cartilage. The upper sac is in part bounded by a shell-shaped, concave cartilage (Concha narium, of various authors; Os lachrymale, Born), which covers it anteriorly and externally, and is attached by a small base to the roof of the lower sac (Fig. 239, l), its upper border bounding the anterior naris (Fig. 15). The upper and external parts of the upper sac have no cartilage. The cartilages of the outer wall of the lower, blind sac extend backwards to the point where the maxillary sinus commences to descend: the roof, however, is prolonged further backwards by two small cartilaginous processes; the inner is short, the outer forms the roof of the descending arm of the sinus, and joins a cartilaginous process, which commences at the anterior portion of the roof of the nasal cavity, passes backwards and downwards to a broad plate, and forms an incomplete outer wall to the nasal cavity. There are also three cartilaginous processes--α. One arising from the outer side of the floor at the level of its junction with the anterior wall; it is a flattened process and passes outwards, and bifurcates at its end to meet the premaxillary and maxillary bones (this is the Oberkieferfortsatz of Ecker), (p. 28, Fig. 14 n″). β. A delicate process on either side, described by Wiedersheim (see p. 280). γ. The third pair of processes are fully described for the first time by Born; each arises at the lower border of the corresponding Concha narium, passes forwards and downwards under the ascending process of the premaxillary to the point where process β is attached to this bone. The processes are flat and approach one another obliquely; in older animals they are united at the point of contact.

At the junction of the anterior wall, the septum, and the floor is a large aperture in the cartilaginous capsule, through which passes the chief nasal branch of the trigeminus, which supplies numerous branches to the intermaxillary gland.

*c.* The *glands* of the *nasal region* are Bowman’s glands, the intermaxillary glands (Wiedersheim), the lower nasal gland (Born), the upper nasal gland (Born), the pharyngeal gland (Born), and the lachrymal duct.

I. A. Bowman’s glands in situ from Rana temporaria; after C. K. Hoffmann. Magnified 150 times.

B. Section of Bowman’s gland; after C. K. Hoffmann. Magnified 300 times.

II. Vessels of nasal mucous membrane of Rana esculenta; after Langer. Blood-vessels striped, lymphatics shaded. ]

(1) The *intermaxillary gland* (see p. 280).

(2) The *lower nasal gland* is placed along the septum and extends as far back as the posterior nares, opening by its ducts (Figs. 238 and 239 gni) into the inferior blind sac of the nasal cavity. In histological structure it corresponds with the intermaxillary glands, except that the glandular tubes are somewhat smaller, and the glandular epithelium stains somewhat less easily with carmine (Born).

(3) The *upper nasal gland* occupies the space between the Concha narium (Os lachrymale, Born) and the neighbouring cartilages, it also surrounds the anterior naris and the opening of the lachrymal canal (Figs. 238 and 239 gns). The numerous ducts open on the mucous membrane covering the oblique cartilage (above described, as passing from in front, downwards and backwards, and forming an incomplete outer wall of the cavity), and its hinder prolongation.

(4) The *pharyngeal gland* is placed transversely behind the posterior nares, and surrounds the vomerine teeth. A portion of the ducts open into the posterior nares, the remainder on the mucous membrane of the pharyngo-oral cavity at two symmetrically placed points (Fig. 238 R).

(5) The *lachrymal duct* (see p. 428) opens into the nasal cavity at the point where the lateral sinus opens into the external chamber of the superior nasal sinus.

(6) [The *glands* of *Bowman* (Fig. 240 I) are freely distributed in the nasal mucous membrane. Each gland is usually rounded or flask-shaped, and consists of a single layer of large epithelial cells possessing distinct nuclei and nucleoli. The epithelium of the glands possesses no basement membrane (M. Schultze and Hoffmann), but is bounded externally by a layer of nerve-fibres and connective-tissue.

The glands situated more superficially have straight ducts opening on the surface; those placed more deeply have usually curved ducts (Paschutin).]

*d.* The *mucous membrane* of the nasal cavities. That part of the superior sinus immediately around the anterior naris is lined with stratified epithelium; the rest of the nasal cavity is lined with columnar ciliated epithelium The epithelial layer rests on a subepithelial network, and this again on a submucous connective-tissue layer possessing numerous vessels and nerves.

(1) The *epithelial layer* (Fig. 241) consists of columnar cells, which in the olfactory region are of two kinds; in other regions the epithelium consists of closely-applied ciliated, thick cells, possessing large oval nuclei, and having irregular, branched bases or ‘feet.’ The cells are 0.032–0.048 mm. long; the nuclei 0.016–0.018 mm long, and 0.006–0.008 mm. broad. The free borders of the cells bear a number of fine cilia.

In the olfactory region a second set of cells, olfactory cells, are met with; these cells (Fig. 241 II) possess each an oval body, enclosing a large nucleus, and a peripheral and central process. The peripheral processes reach to the general surface of the surrounding epithelium and there terminate in a number (5–8) of stiff cilia; these cilia are sometimes 0.09 mm. long, they are thicker at their bases than the ordinary cilia (Schultze); according to Hoffmann, a second system of stiffer and longer cilia is met with; of which each olfactory cell possesses as a rule only one. The bodies of the olfactory cells are 0.009–0.010 mm. long, and 0.007–0.008 mm. broad; the peripheral processes vary considerably in length, according to the position of the body (0.03–0.05 mm.). The central processes vary from 0.02–0.03 mm. in length. The peripheral processes are considerably thicker than the central processes. No membrana limitans olfactoria has been discovered in the frog.

(2) The *second layer* consists of a network of processes belonging to the bases of the central processes of the superimposed epithelial and olfactory cells. Numerous highly refractive nuclei possessing nucleoli are situated in the meshes of this network; they correspond in all particulars with the nuclei of the olfactory cells (M. Schultze). According to Exner the branched processes of the epithelial cells and of the olfactory cells unite to form a complex plexus. Other observers, Paschutin, Cissoff, v. Brunn, Schultze, and Hoffmann oppose this view, and hold that the central processes of the olfactory cells do not unite with the processes of the epithelial cells, but that they are in direct continuity with the fibrils of the olfactory nerve. This view is probably correct.

Separations from the olfactory mucous membrane of Rana temporaria; after C. K. Hoffmann.

I. Surface view of the olfactory mucous membrane. Magnified 350 times.

II. Epithelial and olfactory cells. Magnified 600 times.

III. Epithelial cells. Magnified 600 times. ]

The submucous layer has a loose connective-tissue matrix, which encloses the glands, nerves, and vessels; according to Paschutin two pigment-layers may be distinguished: the one, immediately under the middle layer of this mucous membrane, is continuous and deeply pigmented; the second is deeper and does not form a continuous layer. This layer is extremely rich in blood-vessels and lymphatics (Langer and Paschutin), (Fig. 240 II). The lymphatics are relatively very large and are very numerous (Langer).

In this layer the central processes of the olfactory cells form bundles of fibres, lying parallel with the surface of the mucous membrane (Paschutin, Cissoff, and Schultze).]

V. THE EAR.

(Re-written by the translator from Das Gehörorgan der Wirbelthiere, by G. Retzius, 1881.)

The organ of hearing is divisible into two parts, the tympanum or middle ear, and the labyrinth or internal ear; an external ear is absent, unless a very slight depression of the tympanic membrane be regarded as such.

A. The *tympanum* (Cavum tympani) is a cavity, bounded externally by the tympanic membrane and internally by the capsule of the internal ear; it communicates by means of the Eustachian tube (tuba Eustachii) with the pharyngo-oral cavity (Fig. 178).

*a.* The *tympanic membrane* lies immediately underneath the skin, but can be separated from that structure; externally it possesses a very slight depression, the only trace of an external ear found in the frog.

The tympanic membrane is of a rounded oval form, being a little wider in the transverse than in the longitudinal diameter; the membrane is directed outwards.

After detaching the skin (Fig. 242 I) the membrane is seen to be attached by its circumference to a ring of cartilage (Annulus membranae tympani; see also p. 26) (at); the ring is attached anteriorly and above to the squamosal bone (sq), and in the rest of its circumference to the surrounding soft parts, i.e. the M. depressor maxillae (dm), the M. temporalis (t), and their fasciae. In the middle of the membrane is a small, rounded, white part (col) which can be traced backwards and upwards towards the circumference.

The membrane consists of fibres of connective-tissue which radiate peripherally from the central point of attachment of the columella; in the peripheral portion unstriated muscular fibres are also found (Leydig).

I. The tympanic membrane of Rana esculenta; natural size. After Retzius.

II. The tympanum as seen after removing the tympanic membrane; natural size. After Retzius.

at Annulus membranae tympani. col Columella. ct Fissure-like cavity. dm M. depressor maxillae. mt Tympanic membrane. sq Squamosal. t M. temporalis. ]

Internally the tympanic membrane is covered by columnar epithelium, a continuation of the mucous membrane lining the tympanic cavity.

*b.* The *tympanic cavity* (Fig. 242 II) is seen, after removing the tympanic membrane, as a flattened, funnel-shaped cavity. The walls of the cavity are lined with a pigmented mucous membrane, under which the cartilaginous ring (annulus membranae tympani) extends internally to form the greater part of the wall of the cavity. The cavity is an elongated oval slit (Fig. 242 II, ct), with its longer axis directed from above and in front, downwards and backwards, and leading inwards; it is bounded above, below, and in front by the squamosal, behind by the soft parts; above in the roof is the cartilaginous part of the columella. The inner or deeper portion of the tympanic cavity is bounded in front by the squamosal, and by the squamous process of the prootici (proc. squamosus prootici) in front and above; internally by the cartilage (primordial-cranium) between the prootic and the exoccipital; behind by the M. depressor maxillae. This part of the cavity is rounded and covered with mucous membrane, and has in its roof the bony part of the columella, which covers the foramen ovale (fenestra ovalis) by its oval, widened end-piece. This deeper portion of the cavity communicates by a short, wide Eustachian tube with the pharyngo-oral cavity; the tube is wide and is of a rounded oval form in section: anteriorly, externally, and internally it is bounded by the pterygoids, posteriorly by soft parts, in which is embedded the styloid process.

The tympanic cavity can be examined from without after removing the tympanic membrane, or from below by means of the Eustachian tube.

*c.* The *columella auris* (Figs. 12, 243) is described by Retzius as consisting of three portions, of which the middle is bony, the external and internal cartilaginous. Parker divides it into four parts (see pp. 25, 26).

The *extrastapedial* (Fig. 243 a′, a″) is attached to the middle of the tympanic membrane by the oval surface opposite a′, and is attached by the process a‴ to the annulus tympanicus; this process of Retzius is the *suprastapedial* of Parker.

The *mediostapedial* (Parker), or middle bony piece of Retzius (Figs. 12 a′, 243 b, b′), is narrow externally but widens internally to articulate with the interstapedial. Just before reaching the latter it gives off a process (b′), to which are attached a few fibres of striated muscle (m).

The columella; after Retzius. Magnified eight times.

A. Seen from above. B. Seen from behind.

a′ Extrastapedial (Parker). Outer cartilaginous portion attached to middle of tympanic membrane (Retzius). a″ Attachment of extrastapedial to mediostapedial. a‴ Suprastapedial (Parker). Portion embedded in mucous membrane (Retzius). b′ Mediostapedial (Parker). Bony part (Retzius). b″ Process of mediostapedial. c Interstapedial (Parker). Inner cartilaginous piece (Retzius). m Insertion of small muscle. ]

The *interstapedial* (Figs. 12 a, 243 c) is cartilaginous; it is thick with a sharply cut-off, slightly concave end, which is placed against the fenestra ovalis. The inner surface of the interstapedial is, however, distinctly larger than the opening of the fenestra ovalis, consequently it does not fit in accurately, but is attached to the border of the opening by means of connective-tissue; the margins of the fenestra ovalis are hollowed (Fig. 245 II) so as to form a fossa fenestrae ovalis, and it is really to the margin of this fossa that the connective-tissue capsule of the interstapedial is attached.

B. The labyrinth or internal ear is contained in a capsule formed of bone and cartilage.

*a.* The *capsule of the labyrinth* (Fig. 244) is formed of two bones, the prootic and the exoccipital (according to Hasse this includes the opisthotic), which are united by cartilage belonging to the primordial-cranium. The fronto-parietal, squamosal, and parasphenoid take only an indirect part in its formation.

On the whole the anterior half of the capsule is formed by the prootic, and the hinder half by the exoccipital; the cavity has its long axis directed from within and above, downwards and outward; the cavity is comparatively large and rounded, and contains the membranous ear.

Four surfaces can be distinguished: a supero-external, an interno-inferior, an anterior, and a posterior (Retzius).

(1) The *supero-external surface* is divided into two parts by a strong, transverse, bony ridge, the processus squamosus prootici. The upper half is concave, is directed upwards and outwards, and is formed by the prootic; it is separated from the anterior surface by a bony ridge, which marks the position of the anterior semicircular canal. Posteriorly and medianly it is separated from the posterior surface by a cartilaginous ridge, running from above, downwards and outwards, which marks the position of the posterior semicircular canal. The cartilaginous hinder root of the processus squamosus prootici arises in the cartilaginous ridge just mentioned, and runs outwards and forwards, covering the external semicircular canal.

Antero-posterior section through the capsule of the right labyrinth of Rana esculenta; after Retzius. Enlarged five times.

ac. Aquaeductus cochleae. av. Aquaeductus vestibuli. cp. Posterior semicircular canal. cra. Canalis rami anterioris acustici. crp. Canalis rami posterioris acustici. fr. Fenestra rotunda. fsc. Fovea sacculi et cochleae. ft. Trigeminal foramen. kn. Cartilaginous suture. ol. Exoccipital. pr. Prootic. ps. Parasphenoid. ]

The lower half of the supero-external surface (under the processus squamosus) is irregularly concave; immediately under the proc. squamosus is a shallow groove in the prootic; it is continued on the exoccipital to the jugular foramen. The remaining part of this surface consists of a rounded cartilage, and is part of the primordial-cranium cartilage between the prootic and the exoccipital; posteriorly it has a small oval aperture, the foramen ovale (fenestra vestibulare), which with the groove is covered by the columella. Above the aperture the cartilage narrows and is continued to the processus squamosus.

(2) The *posterior surface* is directly continuous with the supero-external surface, and is formed by the exoccipital. This surface lies behind the ridge formed by the posterior semicircular canal, it is concave, and has two small apertures, separated by a narrow, bony process, and situated near the jugular foramen; these are the foramen rotundum (fr.) and the aquaeductus cochleae (ac.).

(3) The *anterior surface* is altogether bony and formed by the prootic (pr.); the anterior surface of this part of the wall is continuous with the surface of the cranium, and abuts on to the large trigeminal foramen (ft.); below it is continuous with the under surface of the cranium, below and externally it articulates with the pterygoid.

(4) The *interno-inferior surface* is as a whole hollowed internally, the upper part being pushed in towards the cranial cavity. It is formed by the prootic anteriorly, by the exoccipital posteriorly, and is completed by the cartilage lying between these bones. In the middle of the upper part of the cartilage is a small oval opening (av.), the ap. aquaeductus vestibuli: about midway between this aperture and the jugular foramen is a second opening in the cartilage (cra.), the opening of the canalis rami anterioris (vestibularis) acustici: a little behind and above this is the opening of the canalis rami posterioris (cochlearis) acustici, situated in the exoccipital. The cartilage between the prootic and exoccipital in the lower half of the interno-inferior surface rests on the parasphenoid.

*b.* The *position* of the *soft parts* in the capsule. The large outer, rounded part of the cavity contains the saccule and cochlea (fovea sacculi et cochleae) (fsc.). Above, the cavity is more irregular, and contains the utricle and the sinus utriculi superior. In front and externally, imbedded in a deep groove, are the anterior and external ampullae (fovea ampullae anterioris et amp. externae); to these are attached the corresponding semicircular canals. The anterior semicircular canal opens above and externally into the canal of the sinus utriculi superior; the posterior passes into a groove for the posterior ampulla (fovea ampullae posterioris), and opens above and internally into the posterior semicircular canal. The external semicircular canal courses in the processus squamosus prootici, the posterior in the cartilage (Fig. 244 cp) between the prootic and exoccipital, and the anterior in the prootic. The upper and posterior part of the anterior semicircular canal is imbedded in cartilage, on which rests the parasphenoid.

*c.* The *perilymphatic space* (Fig. 245 I and II). The membranous labyrinth does not occupy the whole space enclosed by the hard parts but is surrounded by the perilymphatic space, which contains the perilymph. The periosteum and perichondrium form the outer lining of the space, and are for the most part pigmented:

The perilymphatic space is widest in the lower part of the organ, in the region of the fovea sacculi et cochleae, especially externally and behind (per); in front it is much narrower (per^1). A little higher, in the region of the tegmentum vasculosum, the space is wanting, as the membranous labyrinth is here attached to the periosteum.

Around the utricle and saccule the space is comparatively wide; it is continued into the bony canals and ampullae. In the semicircular canals the space is wider on the concave side than on the convex side, the membranous canals being placed eccentrically, as are also the ampullae, though to a less extent. The periosteum and perichondrium lining this cavity form a very delicate, pigmented membrane, formed of numerous fine elastic fibres which cross each other irregularly; its inner surface is lined with an incomplete layer of branched protoplasmic cells with large oval nuclei. From this membrane numerous irregular bundles of fibres, in the form of trabeculae, pass into the space and form a rich network, which is attached internally to the outer surface of the membranous labyrinth and holds it in position. Free nucleated leucocytes are occasionally met with in the meshes of this network. The perilymphatic space is prolonged into two subsidiary cavities:--

The membranous labyrinth of Rana esculenta, within its natural covering of periosteum; after Retzius.

I. Seen from the side; magnified ten times.

II. The hinder half; magnified ten times. Seen obliquely from above, and in front, and from the side.

aa Anterior ampulla. adf Apertura fenestrae ovalis. al. Apertura lagenae. ap. Posterior ampulla. apb. Opening into the pars basilaris. ca Anterior semicircular canal. ce External semicircular canal. cp Posterior semicircular canal. dfo Ductus fenestrae ovalis. dp Ductus perilymphaticus. dp′ Saccus perilymphaticus. l. Lagena cochlea. ms. Macula sacculia. pb Pars basilaris cochleae. per Wider part of perilymphatic space. per^1 Narrower part of perilymphatic space. ra. Ramus anterior. rn. Ramulus neglectus. rp. Ramus posterior. rs. Ramulus sacculi. s. Saccule. sfo Saccus fenestrae ovalis. spl Saccus perilymphaticus. tv Tegmentum vasculosum. u Utricle. ]

(1) The *ductus fenestra ovalis* (Retzius), (Fig. 245 dfo) commences as an opening (adf) immediately opposite the foramen ovale of the hard capsule, which leads into a moderately large canal, the structure under consideration. It passes forwards and outwards through the fenestra ovalis between the interstapedial and the outer wall of the capsule into the oval depression (fossa fenestrae ovalis), and rapidly widens to form a short, flattened, blind sac (saccus fenestrae ovalis), which is lodged in the fossa (sfo). Its walls are thin and pigmented.

Part of the outer wall of the perilymphatic space: after Retzius. Vérick’s Syst., Obj. III, Oc. 3.

per. Periosteum. pg. Perilymphatic network. zn. Leucocytes. ]

(2) The *ductus perilymphaticus* (Hasse), (Fig. 245 dp) passes above and behind the ductus fenestrae ovalis, behind the auditory-nerve, and near the cochlea, then behind and above the lagena to the aquaeductus cochleae (Fig. 244 ac), where it forms a short, wide tube, which passes backwards and inwards through this canal to the canalis jugularis; here it lies close to the nerves and forms a short oval sac (saccus perilymphaticus) (dp′), which communicates with the sub-arachnoid space of the cranial cavity by means of a tube from the neck of the sac. The walls of this structure are thin and formed of connective-tissue with very few pigment-cells. The other extremity of the tube passes to the pars basilaris and under the sinus post. utri., between it and the pars neglecta; it then courses to the outer side of the hinder end of the external semicircular canal: the tube then bends downwards to the outer side of the utricle and saccule to open into the general perilymphatic space.

*d.* The *membranous labyrinth* (Figs. 247, 248) has the following parts: the utricle and sinus superior, the recessus utriculi, the anterior semicircular canal and anterior ampulla, the external semicircular canal and external ampulla, the posterior semicircular canal and the posterior ampulla, the saccule, ductus endolymphaticus, and saccus endolymphaticus, the pars neglecta, the lagena cochleae, the pars basilaris cochleae, and the so-called tegmentum vasculosum.

In addition the following nerve-terminations can be distinguished: (1) The macula ac. recessus utriculi, (2) the three cristae acusticae ampullorum, (3) the macula ac. sacculi, (4) the macula ac. neglecta, (5) the papilla ac. lagenae cochleae, and (6) the papilla ac. basilaris cochleae.

The auditory nerve divides immediately beyond its origin from the medulla oblongata to form a ramus anterior and a ramus posterior, which course alongside each other for a short distance, the latter lying behind and above the former. The R. anterior runs forwards and outwards under the utricle, giving off the R. sacculi, which runs downwards and outwards; the R. rec. utriculi is then given off as a number of fibres, which run upwards and forwards; the main nerve then divides to form the R. ampullae anterioris and the R. ampullae externae, which course together for a short distance and then separate to reach their respective ampullae. The R. posterior runs backwards and outwards, gives off the R. lagenae, and then divides to form the R. neglectus, running upwards, the R. basilaris running downwards and backwards, and the R. ampullae posterioris which courses backwards and outwards.

(1) The *utricle* (utriculus) (Figs. 247 and 248 u) is irregularly cylindrical in form: commencing at the recessus utriculi it passes forwards and outwards; then backwards, inwards, and upwards, to terminate at the sinus posterior, where it is slightly contracted. At about its middle it is divided into an anterior and a posterior part by an incomplete, sickle-shaped partition, formed by the posterior semicircular canal opening obliquely into the utricle, and so causing a fold in the posterior wall: on the anterior wall there is no fold; the aperture left in the partition is the apertura utriculi.

The posterior part of the utricle receives the sinus superior, which is formed by the junction of the two vertical semicircular canals. The anterior part of the utricle receives the hinder dilated end of the external semicircular canal by an opening in its posterior wall, close to the apertura utriculi. In the lower wall or floor is the narrow opening leading into the saccule (canalis utriculo-saccularis): this opening is placed with its long axis parallel to the long axis of the utricle, with its broader end posterior, and the narrower end anterior.

(2) The *recessus utriculi* (Figs. 247 and 248 rec). The anterior end of the utricle widens and curves downwards and outwards to form the recessus utriculi; on its floor is a thin, kidney-shaped plate or otoliths, resting on the macula ac. recessus utriculi (mu), which receives the ramulus rec. utriculi; under it the ramulus amp. anterioris and the ramulus amp. externae run forwards and close together to reach their respective ampullae, which are close together at the antero-external wall of the recessus utriculi. The otolith is a glassy, homogeneous plate, with numerous vacuole-like spaces and striated borders; it covers the whole of the macula.

The right membranous labyrinth of Rana esculenta; after Retzius. Magnified 20 times. Fig. 247 seen from the inner side; Fig. 248 seen from the outer side.

aa Anterior ampulla. ae External ampulla. ap Posterior ampulla. apn Apertura partis neglectae. au Apertura utriculi. ca Anterior semicircular canal. ce External semicircular canal. cp Posterior semicircular canal. cus Canalis utriculo-saccularis. de Ductus endolymphaticus. l Lagena cochleae. mn Macula acustica neglecta. ms Macula acustica sacculi. mu Macula acustica recessus utriculi. pb Pars basilaris cochleae. pl Papilla ac. lagenae. ppb Papilla ac. basilaris. raa Ramulus ac. anterioris. rae Ramulus amp. externae. rap Ramulus amp. posterioris. rb Ramulus basilaris. rec Recessus utriculi. rl Ramulus lagenae. rn Ramulus neglectus. rs Ramulus sacculi. s Saccule. sp Sinus utriculi posterior. ss Sinus utriculi superior. tv Tegmentum vasculosum. u Utriculus. ]

(3) The *anterior ampulla* and *semicircular canal* (Figs. 247, 248, aa, ca). The anterior ampulla is a rounded, oval vesicle, with a depressed roof (Fig. 250 I); on the floor is a transverse low septum, which bears the crista acustica (cr) on its free border; seen from above the crista acustica (Fig. 249 II, aa, cr) has concave borders anteriorly and posteriorly; the ends are broad, rounded, and somewhat raised; and in the middle it presents a small elevation (Fig. 249 cr). On the crista acustica rests the cupula terminalis (Fig. 250 I, cu); this is arched above but of the same form as the crista acustica below, from which it is separated by an even slit-like space; the ends are not rounded but hollowed out. The substance of the cupula is very soft and has parallel striations, formed of fine fibres and running from above downwards; it separates very easily from the crista acustica. The anterior ampulla is directed forwards, outwards, and slightly upwards, to open into the anterior semicircular canal (canalis m. anterior) (ca), which curves first upwards and forwards, then backwards, inwards, and upwards, to open by means of a slightly dilated end into the sinus superior utriculi.

(4) The *external ampulla* and *semicircular canal* (Figs. 247, 248 ae, ce). The external ampulla lies immediately external to the anterior ampulla; it also is an oval vesicle, and corresponds with the anterior ampulla in size and shape, except that the roof is higher. The roof is directed backwards, the floor forwards; the septum transversum is low, placed vertically, and bears a triangular, slightly depressed crista acustica: the broader, rounded end of the crista is directed upwards, the apex downwards. The corresponding cupula terminalis is relatively high, and is of the same shape as the crista, and is striated. The external ampulla is continuous with the external semicircular canal (canalis m. externus) (ce), which courses outwards and backwards; then backwards, inwards, and slightly upwards, touches the roof of the posterior ampulla; then curves forwards and inwards to terminate by a slightly dilated end in the anterior part of the utriculus.

(5) The *posterior ampulla* and *semicircular canal* (Figs. 247, 248, and 249 ap, cp). The posterior ampulla commences at the posterior end of the sinus post. utriculi, and is directed outwards and backwards. It corresponds in all other points with the anterior ampulla. The posterior semicircular canal (ce) (canalis m. post.), into which the ampulla opens, curves upwards, inwards, and forwards, to open into the upper end of the sinus superior.

The membranous labyrinth of Rana esculenta; after Retzius.

I. Part of membranous labyrinth to show relations of the ductus and saccus endolymphaticus to the cochlear part; magnified.

II. The recessus utriculi and the external ampulla; magnified.

III. To show tegmentum vasculosum, pars basilaris, pars neglecta, etc.

IV. To show relations of the cochlear part to the pars neglecta.

aa. Ampulla anterior. ae. Ampulla externa. al. Apertura lagenae. ap. Posterior ampulla. apn Apertura partis neglectae. au. Apertura utriculi. ca. Canalis m. anterior. ce. External semicircular canal. cp. Posterior semicircular canal. cpb. Opening into pars basilaris. cr. Crista acustica. cus. Canalis utriculo-saccularis. de. Ductus endolymphaticus. dp. Ductus perilymphaticus. l. Lagena cochleae. ma. Macula ac. recessus utriculi. mn. Macula ac. neglecta. mp. Membrana basilaris. pb. Pars basilaris cochleae. pe′. Dark spot on either side of crest of ampulla. pl. Pars ac. lagenae. pn. Pars neglecta. ppb. Papilla ac. basilaris. ra. Ramus anterior. raa. Ramulus amp. anterioris. rae. Ramulus amp. externa. rap. Ramulus amp. posterioris. rb. Ramulus basilaris. rec. Recussus utriculi. rl. Ramulus lagenae. rn. Ramulus neglectus. rp. Ramus posterior. rs. Ramulus sacculi. s. Saccule. sp. Posterior semicircular canal. spl. Saccus perilymphaticus. ss. Sinus utriculi superior. tv. Tegmentum vasculosum. u. Utricle. ]

(6) The *saccule* (s), *ductus endolymphaticus* (de), and the *saccus endolymphaticus* (Figs. 247, 248, 249). The saccule (s) is an oval vesicle, placed under the anterior part of the utricle and directed outwards and downwards; below it is flattened in a direction from in front and within, outwards and backwards; above it is wider. In the inner and anterior surface is the rounded, oval macula acustica sacculi (Figs. 247 and 248 ms), to which is distributed the R. sacculi (rs) from above; a large otolith rests on the macula and occupies a large portion of the cavity, more especially the lower portion. The tubular ductus endolymphaticus (de) arises by a narrow oval opening placed in the upper and inner part of the wall, runs upwards and to the angle between the utricle and the sinus superior, continues in the same direction for a short space, and then curves inwards to pierce the apertura aquaeductus vestibuli, and so reach the cranial cavity. It then forms a large, thin-walled sac (saccus endolymphaticus), placed between the brain and cranium. The sac is very vascular and contains crystalline otoliths.

(7) The *pars neglecta* (Figs. 247, 248, 249) was described by Hasse as the ‘first part of the cochlea’ (‘Anfangstheil der Schnecke’), but according to Retzius it does not belong to the cochlea. It is placed above and in front of the pars basilaris cochleae, above and a little behind the lagena cochleae, therefore above the upper and posterior part of the saccule, and under the middle part of the utricle. It is really a prolongation of the saccule, with which it communicates by an elongated oval opening placed externally and immediately below the opening of the canalis utriculo-saccularis. It is an oval vesicle, with its roof intimately united with the lower wall of the utricle; anteriorly it is broad, posteriorly narrowed. The macula acustica neglecta is attached to the roof of the vesicle and consists of an anterior heart-shaped and a posterior semilunar portion united by a narrow connecting piece (Fig. 250 III and VII). The ramulus neglectus divides into two branches, which supply the two parts of the macula. On the macula acustica neglecta rests the membrana tectoria (Deiters); the membrane is S-shaped, with the anterior end narrow, the posterior broad (Fig. 250 VII); the borders of the membrane are pierced by numerous small round holes, the central part has smaller and fewer perforations, and is finely striated. From the middle of the posterior part of the upper surface a thicker portion projects downwards into the cavity of the pars neglecta; it has a narrow, deep notch for the nerve at about its middle; anteriorly it points towards a sickle-shaped piece, which is curved inwards. Canals run obliquely downwards and inwards from the apertures on the superior surface. The membrane is clear, homogeneous, partly finely striated, and corresponds with the membrana tectoria of the pars basilaris, etc.

(8) The *lagena cochleae* (Figs. 247, 248, and 249 l) is an oval swelling of the membranous labyrinth; it lies close to the sacculus with its broader end forwards, the narrower directed backwards. By a large rounded opening at the posterior end it communicates with the saccule by means of a rounded space common to the lagena cochleae and the cochlea. The papilla acustica lagenae (pl) is situated in the posterior wall of the lagena; it is elongated, oval, and supplied by the ram. lagenae. The papilla is covered by a plate-like otolith formed of numerous rounded particles.

The membranous labyrinth of Rana esculenta; after Retzius.

I. Transverse section of the anterior ampulla. Magnified 50 times.

II. Piece from under surface of the cupula from the anterior ampulla. Vérick’s Syst., Obj. VIII. Oc. 3.

III. The macula acustica neglecta, seen from below. Vérick’s Syst., Obj. IV, Oc. 3.

IV. Part of wall of the anterior ampulla.

V. Part of the cochlea, the pars basilaris cut longitudinally. Vérick’s Syst., Obj. I, Oc. 3.

VI. Longitudinal section of the pars basilaris. Vérick’s Syst., Obj. I, Oc. 3.

VII. The macula ac. neglecta, seen from below. Vérick’s Syst., Obj. IV, Oc. 3.

VIII. The pars basilaris, seen from behind and the outer side. Vérick’s Syst., Obj. I, Oc. 3.

IX. Transverse section of the external ampulla. Magnified 175 times.

apb Oval opening into sacculo-cochlear space. cr Crista acustica. cu Cupula terminalis. dp Ductus perilymphaticus. mb Section of thinner wall of pars basilaris. mt Tectorial membrane. mw Thickened membranous wall. n Nerve-fibres. pb Pars basilaris. pe′ Area of coarsely granular cells. ppb Papilla acustica basilaris. r Epithelium on raphe. rb Ramulus basilaris. rn Ramulus neglectus. tv Tegmentum vasculosum. ]

(9) The *pars basilaris cochleae* (Figs. 247, 248, and 249 pb) is placed on the posterior thickened wall of the saccule and lies above and behind the lagena. It forms a small, oval, pocket-like protuberance, with the long axis directed from in front and above, backwards and outwards, its opening being directed forwards and outwards. The short ram. basilaris passes in from above to supply it. The walls of this dilatation are thick and stiff, with the exception of a small portion, the membrana basilaris (Hasse) (mb), which closes the opening into a small dilatation on the anterior inner wall. The ramulus basilaris (rb) divides into, at least, two branches, and passes close to the membrana basilaris (mb), where the elongated and oval papilla ac. basilaris (Fig. 250 ppb) is placed. The papilla is covered by a membrana tectoria (Fig. 250 mt), which is often found separated from the papilla, probably by the action of the reagents used. The form of this membrane is peculiar but will easily be understood from the figure (Fig. 250 mt). In structure it is similar to the corresponding structures found in other parts of the ear.

Preparations from the ear of Rana esculenta; after Retzius.

I. Part of the membranous wall seen from the surface. Vérick, Obj. VI, Oc. 3.

II. Transverse section of the membranous wall. Vérick, Obj. III, Oc. 3.

III. Epithelium from the neighbourhood of the macula ac. rec. utriculi. Vérick, Obj. III, Oc. 3.

IV. Branched cells from the yellow spot on the floor of the anterior ampulla. Vérick, Obj. III, Oc. 3.

V. Epithelium from the roof of the anterior ampulla. Vérick, Obj. III, Oc. 3.

re Epithelium of raphe. e Pavement epithelium. pe Protoplasmic cells. pg Perilymphatic tissue. ]

(10) The *tegmentum vasculosum* (Deiters) (Figs. 245, 248, and 250 tv) is an oval, shell-shaped dilatation of the membranous labyrinth; its long axis is directed from above and in front, downwards and backwards. The walls of the tegmentum are thin and intimately attached to the periosteum.

*e.* The *minute structure* of the membranous labyrinth (Figs. 251 252).

(1) The *walls* of the membranous labyrinth have the same general structure throughout: the walls are usually thicker at the nerve-terminations, in the ampullae, semicircular canals, pars neglecta, and especially the pars basilaris; the wall of the tegmentum tympani are the thinnest. The walls are transparent, homogeneous, refractive, and, at places, show a faint striation, which is, as a rule, not due to the presence of fibres; in parts of the recessus utriculi, and in the outer wall of the saccule, especially near the tegmentum vasculosum, more or less distinct fibres can be made out. Sections of the wall show spindle-shaped cells, with the processes usually arranged parallel to the surfaces; seen from the surface, the cells are seen to branch in all directions (Fig. 251 I, II). In the thinner parts of the walls the cells are few or altogether absent. The outer surface of the membranous labyrinth is uneven, in consequence of the attachment of the perilymphatic network. Blood-vessels are also attached to the outer surface, and pierce the wall, especially near the nerve-terminations.

The whole of the inner surface is lined with a layer of polygonal, tesselated epithelium-cells. The size and height of the epithelium varies in different parts. On the outer wall of the saccule the cells are large, but on the inner wall small; they are also large in the semicircular canals, except on a small raphe on the inner and outer side, where they are smaller but higher (Fig. 251 re); in the ampullae the cells are large, except on the roof. In the utricle and sinus superior they are also moderately large. In addition to the places mentioned, a smaller epithelium is found on the floors of the ampullae, in the recessus utriculi, and near all the nerve-terminations and on the sides of the ampullar septa. Surrounding the nerve-terminations of the macula rec. utriculi, macula sacculi, and papilla lagenae are found narrow, branched, yellowish cells (Fig. 251 pe) with spindle-shaped nuclei. Cells of a third kind, first described by Deiters, Hasse, and Kuhn, in the tegmentum vasculosum, and in the ampullae by Hasse and Kuhn, are also found in the utricle. They contain a yellowish pigment, and are collected into two sharply differentiated groups in each ampulla (Hasse has one placed before and one behind the septum on the floor). The cells are cylindrical, the upper parts striated, the lower narrower, and the bases again widened to a polygonal, more homogeneous plate, which is fixed to the wall. On the tegmentum vasculosum the corresponding cells are not so high.

(2) The *nerve-terminations*. The larger branches of the auditory nerve contain medullated fibres of various dimensions and bipolar, spindle-shaped ganglion-cells. The nerves pierce the walls obliquely or vertically, and retain their medullary sheaths until near their final distribution. On each of the nerve-terminations is found nerve-epithelium, which varies in height in different parts. In the crista acustica it measures 0.075 mm. in height in the middle part, 0.06 mm. at the sides; on the macula rec. utriculi 0.09 mm., on the macula sacculi 0.075 mm., on the papilla lagenae 0.06 mm., on the papilla part. basil. 0.045 mm., on the macula neglecta 0.075 mm. The epithelium is of two kinds, hair-cells and sustentacular cells.

The nerve-terminations in the membranous labyrinth of Rana esculenta; after Retzius.

I. Vertical section through the crista acustica of the anterior ampulla. Vérick’s Syst., Obj. III, Oc. 3.

II. Vertical section through the macula ac. recessus utriculi. Vérick’s Syst., Obj. VIII, Oc. 3.

III. Three isolated hair-cells from the crista ac. of the anterior ampulla. Vérick’s Syst., Obj. VIII, Oc. 3.

IV. Two isolated sustentacular cells from the crista ac. of the anterior ampulla. Vérick’s Syst., Obj. VIII, Oc. 3.

cr Crista acustica. cu Cupula terminalis. fz Sustentacular cells. h Hairs of hair-cells. hz Hair-cells. n Nerve-fibres. ]

α. The hair-cells (Fig. 252 hz) have, on the whole, elongated, flask-like forms, but are not all of the same length (0.024–0.04 mm.). The free ends of the cells are rounded, flattened, and yellowish, and each bears a stiff cilium, which is fixed by a broad base to the cell, and thins out towards its free end: the cilia vary in length; in the ampullae their greatest length is 0.13 mm., on the macula rec. utriculi 0.011 mm., and on the papilla lagenae 0.017 mm. The cells are granular, possess rounded oval nuclei, and are fixed by a fine, narrow process (Fig. 252 hz), though they usually seem to be rounded off without possessing a process.

β. The sustentacular cells. Under the hair-cells is a finely granular substance, possessing numerous rounded oval nuclei, which are placed in superimposed rows (Fig. 252 fz), the deepest row being placed close together and immediately on the membranous wall. After proper treatment and isolation these nuclei are seen to belong to narrow, elongated cells, which rest by a slightly widened base on the wall, and are continued upwards between the hair-cells to reach the surface of the epithelium, where their upper processes are again slightly widened.

γ. The nerve-fibres (Fig. 252 n) lose their medullary coats, ascend towards the epithelium, and frequently divide to form two unequal branches, which ascend to the level of the hair-cells, and curve so as to course horizontally as extremely fine varicose fibrillae; these frequently form a network, of which the exact method of termination has not been made out. In some cases a fine fibril may be traced to the base of a hair-cell, but a direct continuation of the one into the other has not yet been traced.

VI. THE EYE.

(Re-written by the translator.)

The organ of sight, the eyeball (bulbus oculi), together with its appendages (tutamina oculi), will be described in this chapter.

A. The Eye is flattened on the outer surface, more convex on the inner or deeper surface. Its principal axis is directed from behind, forwards and outwards.

The outer transparent portion of the eyeball is the cornea, which forms the outer boundary of the anterior chamber. The larger, white, opaque, and inner portion is the sclerotic coat, which, together with two deeper tunics, the choroid coat and the retina, enclose the posterior chamber of the eye. The pigmented ring placed behind the cornea is the iris, and the aperture it encloses the pupil. The lens is placed immediately behind the iris. On the inner side the optic nerve pierces the sclerotic to enter the eyeball.

*a.* The *sclerotic coat* (sclerotica s. sclera) forms about three-fourths of the surface of the eyeball; posteriorly it is pierced by the optic nerve at a point (porus opticus) nearer the temporal side than the nasal. The sclerotic coat consists of fibrous tissue externally, with a layer of hyaline cartilage internally (Helfreich). The fibrous layer is formed of bundles of parallel fibres, which cross each other, chiefly at right angles (Hoffmann). The cartilaginous layer ends just behind the line of insertion of the extrinsic muscle of the eye, and is thickest at the point of entrance of the optic nerve (Helfreich).

Endothelium from the inner surface of the sclerotic coat; after Hoffmann. ]

The sclerotic coat is rich in nerve-fibres, which form a close network; the fibres, however, do not unite but form the meshes of the network by simply crossing each at acute angles.

The deeper surface of the sclerotic coat is lined with a layer of large endothelial cells (Hoffmann), (Fig. 253), which form the outer wall of the capsule of Tenon.

*b.* The *cornea* and the *anterior chamber*. The cornea forms about one-fourth of the surface of the eyeball and is directly continuous with the sclerotic. In it five layers can be distinguished: a layer of stratified epithelium or conjunctiva, an anterior hyaline membrane, the true corneal substance, a posterior hyaline membrane, and a layer of endothelium.

(1) The *corneal epithelium* is a layer of stratified epithelium covering the superficial surface of the cornea. The superficial layer forms a beautiful mosaic of polygonal cells; the middle layers are polygonal in all sections, while the deepest layer is more or less columnar. Except in the most superficial layer, all the cells have serrated surfaces. Smaller cells possessing each two nuclei are also found between the columnar cells, and are evidently cells in process of division; according to Waldeyer, cell-proliferation may also take place in the middle layers.

The basal or deeper portions of the columnar cells possess a clear border, which reminds one of the hyaline border found on the free border of columnar epithelium in other parts. The cells are here so closely applied to one another that these borders have the appearance of a continuous, highly refracting membrane (Rollett); according to Henle, the border consists of a network of very fine processes from the cells above.

(2) The *true corneal substance*, and (3) the *anterior hyaline membrane*. The corneal substance consists of flat bundles of fibres arranged in laminae, with cement-substance and connective-tissue corpuscles interposed. The fibrils are extremely fine (0·0001 mm., Engelmann), and bound together into bundles by cement-substance. The bundles of the laminae are arranged at various angles, though many are placed at right angles to each other (Waldeyer).

Between the laminae are flattened spaces, which seen in section are spindle-shaped. By proper treatment they are seen to be irregular, branched spaces, which communicate by fine canals and form part of the Recklinghausen-canals or lymph-system. These spaces contain branched, connective-tissue corpuscles (Toynbee), and a colourless fluid.

The corpuscles (Fig. 254 e) do not fill the spaces which they occupy. They possess large nuclei, surrounded by granular protoplasm.

Preparation from cornea of Rana esculenta; after Klein, Hartnack’s Syst., Obj. VII, Oc. 3.

a Nerve of first order. b Nerve of second order. c Nerve of third order. d Nerve of fourth order. e Corneal corpuscles. ]

The canals by which these spaces communicate (‘Saftcanälchen’ of Recklinghausen) lie, in general, parallel to the surfaces of the cornea, and communicate by joining at acute angles or by short transverse branches. According to Lavdowsky, these canals have a distinct lining membrane.

The anterior hyaline layer (Bowman’s or Reichert’s lamella) is not so well seen in the frog as in some higher animals; it is simply a portion of the corneal substance, of somewhat denser structure than the rest, into which it passes by a gradual transition.

(4) The *posterior hyaline membrane* (Descemet’s membrane) is a highly elastic, very transparent layer, placed behind the true corneal substance; in the frog some few bundles of fibres belonging to the true corneal substance appear to pass into the posterior hyaline layer, although they cannot be traced further through its substance. The structure of the membrane is, in consequence of its transparency, unknown, though the above observation seems to point to a fibrillar origin.

(5) The *corneal endothelium* is a single layer of polygonal cells of 0·02 mm. diameter. The cells possess the power of altering their shape when stimulated (Klebs).

Preparation from cornea of Rana esculenta; after Klein. Hartnack’s Syst., Obj. X immers., Oc. 3.

a Endothelial cells. b Nuclei of endothelial cells. c Nerves of third order in the tissue of the cornea propria. d Nerves of the fourth order. ]

(6) The *nerves* of the cornea are derived from the ramus ophthalmica trigemini; they pierce the sclerotic coat in front of the sclerotic cartilage and then course towards the cornea, at the margin of which they form a coarse network of medullated fibres. From this about thirty nerves pass towards the cornea, which they enter, and then very quickly lose the main part of their medullary sheaths. According to Wolff, a portion of the nerves retain their medullary sheaths, or in some cases appear to regain it after having lost it.

The nerves passing from the plexus (nerves of the first order, Klein) give off smaller branches, which for a short distance have a serpentine or rectilinear course. By a few anastomoses they form a loose plexus (nerves of the second order, Klein). After a longer or shorter course they give off numerous lateral fibres, or terminate in several such fibres arising at one point (nerves of the third order, Klein). These are distinguished by their size, varying only within small limits, and by the possession of more or less regularly placed varicosities; the clearer portions are longitudinally striated as though made up of fibrillae; they have a nearly rectilinear course, and, after a longer or shorter course, turn into a direction which is at right angles to the former one; lastly, they remain for long distances unbranched. These nerves are connected one with another by cross fibres running at right angles to them, and in this way a rectangular trellis-work is formed.

The fibrils (nerves of the fourth order) given off by these nerves form networks around the connective-tissue corpuscles, but no direct connection between nerve and corpuscle has been traced; they always appear to lie on that surface of the corneal corpuscle which is directed towards the superficial surface of the cornea (Klein). In the endothelium covering the membrane of Descemet these fibrils can be traced coursing along the margins of the cells (Fig. 255 d), and sometimes undergoing dichotomous division (Klein).

Almost all observers have described these fibrils as possessing varicosities; Hulke, and more recently Wolf, however, deny their presence. Lavdowsky traces nerve-fibrils to the nuclei of the connective-tissue corpuscles.

(7) The *anterior chamber* is the space between the cornea and the iris, and is filled with a watery fluid, the aqueous humour. At the circumference of the chamber are a number of spaces (spaces of Fontana), formed by interruptions in the tissue between the posterior surface of the cornea and the iris; the result is that bands or trabeculae (ligamentum pectinatum iridis) pass from the one structure to the other, and between these are the spaces of Fontana.

According to Angelucci these trabeculae are of three kinds: trabeculae passing from the cornea to the iris, formed of connective-tissue; trabeculae from the cornea to the ciliary processes, which contain elastic tissue; trabeculae from the interstitial connective-tissue of the ciliary muscle to the cornea, and formed almost entirely of elastic tissue.

At the junction of the cornea and sclerotic, and just in front of the spaces of Fontana, is a larger and similar space, which may be traced round the whole circumference of the cornea; this, the canal of Schlemm (Sinus circularis iridis), is held to be a venous plexus by some observers (Angelucci, and others), according to others it is a lymphatic space in connection with the anterior chamber (Schwalbe, and others). It is certain that the vessels can be very easily injected from the anterior chamber, although a direct communication has not yet been seen.

*c.* The *choroid coat* and the *iris* (tunica choroidea et iris, tunica vasculosa).

The vessels of the choroid and iris; after Hans Virchow.

I. The two roots of the V. bulbi superior. Magnified 10 times. II. Vessels of the iris. Magnified 9 times. III. Origin of the ventral vein. IV. Schema of the choroid vessels; seen from the proximal pole. V. Transverse section through the choroid at the equator. VI. The origin of the choroid arteries from the ophthalmic artery. The greater part of the sclerotic has been removed. Left eye twice natural size. A. From the proximal pole. B. From the temporal side. VII. Part of a choroidal artery attached to the choriocapillaris. Magnified 10 times. VIII. A portion of the choriocapillaris, more highly magnified. IX. The V. ophthalmica and V. bulbi superior on the sclerotic of the right eye. A. Seen from proximal pole. B. Seen from above. Twice natural size.

A Art. ophthalmica. A′ Art. choroidea. An R. nasalis of the ophthalmic artery. At R. temporalis of the ophthalmic artery. ch Area of membrana choriocapillaris. Le Outer pigmented layer of choroid. Li Inner pigmented layer of choroid. N Optic nerve. r Vasa recta. r′ Transitional part between choriocapillaris and ventral whorl. r″ Transitional part between choriocapillaris and upper whorl. R Branches of the circulus iridis major. Rd Distal root of vein of under surface of eye. Rd′ Distal root of nasal vein. Rd″ Proximal root of nasal vein. Rp′ Nasal root of ventral vein. Rp″ Temporal root of ventral vein. Vbs V. bulbi superior. Vh V. hyaloidea. Vo V. ophthalmica. Vp. Proximal root of vein of under surface of eye. Vs′ Nasal root of V. bulbi superior. Vs″ Temporal root of V. bulbi superior. ]

*1.* The *choroid coat* lines the deeper surface of the sclerotic coat, but is also prolonged under the cornea to form the iris. The choroid is firmly attached to the sclerotic in two positions, at the point of entrance of the optic nerve, and at the line of junction of the sclerotic and the cornea. Its external surface is closely applied to the deeper surface of the sclerotic, from which it is only separated by a very narrow serous cavity (supra-choroidal space), and to which it is attached by numerous vessels and nerves. The deep surface of the choroid is covered by the retina, to which it is closely attached, except at the ora serrata, the attachment being especially intimate at the processus ciliares.

The choroid coat consists of a fibrous layer containing corpuscles and traversed by a very rich vascular anastomosis. The corpuscles of this layer are deeply pigmented, in some cases to such an extent that the oval nucleus cannot be seen; the fibrous tissue is also pigmented, and has consequently a brownish tinge. That portion of the layer immediately below the sclerotic is termed the lamina fusca or suprachoroidea, the vessels on the deeper surface forming the membrana choriocapillaris. This again is lined on its deeper surface by a hyaline membrane.

α. The arteries (Fig. 256 VI; VII, VIII) supplying this coat are two branches of the arteria ophthalmica; these form a capillary network (Fig. 256 VII) resembling the corresponding structure found in mammals. The meshes have approximately the same size, while the capillaries themselves vary considerably in size. This network is, however, only complete on the nasal, temporal, and proximal part of the upper surfaces. Towards the corpus ciliare the meshes become wider and elongated; the capillaries then unite at acute angles parallel with the longitudinal axis of the eye. The network (choriocapillaris) exists in a simple layer within the two arteries which form it, and superficial to the veins (Virchow).

β. The veins of the choroid (Fig. 256 III, IV, IX) are (1) a vein which unites at the lowest point of the equator of the eye with the V. hyaloidea to form (2) the V. ophthalmica, two small branches of the V. bulbi superior, which unite outside the sclerotic, and (3) the vasa recta.

(1) The larger vein arises from the greater part of the under surface of the eye; it gives off branches to each side, which radiate to form a ‘whorl’ or star-shaped capillary anastomosis (Fig. 256 III), the two halves of which have no connection. A proximal and a distal root can be distinguished in the anastomosis; the distal lies towards the corpus ciliare, and occupies exactly one-fourth of the circumference of the choroid at its junction with the corpus ciliare.

(2) The two branches of the V. bulbi superior lie alongside the corpus ciliare on the upper surface, and each occupies one-fourth of the circumference; they form a similar though simpler figure (Fig. 256 I) to the foregoing, each forming one half.

(3) The vasa recta are numerous parallel vessels which arise in the iris, and coursing centrally empty themselves into the branches of the V. bulbi superior on the superior surface, and into the branches of the venous capillaries on the inferior surface.

*2.* The *iris* is covered anteriorly by a layer of endothelium, continuous with that covering the posterior surface of the cornea, and of similar character. The border of the pupil (margo pupillaris) is of a golden colour, outside this bright ring to its outer margin (margo ciliaris) the iris is black; the golden colour is due to the presence of cells containing a pale yellow pigment; the nuclei of these cells are round and granular; the cells themselves have rounded outlines (Hoffmann). The black portion of the iris contains more irregular, spindle-shaped cells, with round nuclei, which are hidden by a dense mass of pigment-granules (Iwanoff and Hoffmann).

The true substance of the iris consists of muscle, nerves, blood-vessels, and a connective-tissue stroma, but on the posterior surface is another layer of black, pigmented cells, and this is again covered with a hyaline membrane, in which, however, a fibrous structure may be made out (Koganeï).

The muscle-fibres are long, spindle-cells, which are abruptly swollen in the middle, where the nuclei are situated; the nucleus is oval, 0.009–0.0012 mm. in length, 0.0025 mm. broad, and occupies nearly the whole of the swollen part of the cell (Hoffmann, Grünhagen).

According to Koganeï the iris possesses a M. constrictor iridis (l. c. Berlin Sitzungsber.), but no M. dilatator iridis; in a former publication (l. c. Arch. mik. Anat.) he was unable to find any muscular fibre, and holds the muscle-fibres of Grünhagen to be connective-tissue elements.

The stroma consists of delicate connective-tissue fibrils, enclosing a very large number of pigmented, branched cells.

α. The *arteries* of the iris (Fig. 256 II) arise from an arch (see Vessels of Eye) formed by the A. ophthalmica in the corpus ciliare. It commences between the ventral and temporal surfaces by two branches: one courses along the temporal border, the other along the nasal, to meet each other on the nasal surface; the former courses through one-third, the latter embraces two-thirds of the circumference at the iris.

The temporal artery courses along the ciliary border during the first third of its course, it then gradually approaches the border of the pupil; the nasal artery runs at once towards the pupil. On the nasal border of the pupil they anastomose by their branches, and so form a circulus iridis major.

Except near their termination, no small vessels arise from this arterial circle; in Fig. 256 II, for example, only five larger branches are given off, three from the temporal side and two from the nasal. The five large branches run towards the circumferential border of the iris and break up into numerous vessels, which form a very irregular and open network. From this network arise the vasa recta already described.

*d.* The *lens* is almost spherical, and is composed of cellular elements enclosed in a capsule (capsula lentis).

The capsule is a homogeneous, transparent, structureless, and highly elastic membrane. The deeper surface of the anterior capsule is lined with a simple layer of regular nucleated six-sided epithelial cells.

The lens itself consists of long, flat fibres; seen from the surface these are broad, narrow edge-wise, and in section six-sided prisms. Those lying parallel to the anterior and posterior surfaces are broad and thicker, those towards the border are narrower. These cells are striated, both longitudinally and transversely (Arnold). The cells near the margin, however, have no transverse striation (Hoffmann). The cells of the central parts form a much closer and firmer structure than those at the periphery (Arnold). The peripheral cells are nucleated, and sometimes even possess two nuclei to one cell; the central cells have no nuclei (Arnold).

The cells are held together by a cement-substance and by their serrated surfaces; the serrations are the cause of the transverse striations. The fibres of the lens have a simple arrangement: commencing at the middle point or pole of one surface they pass over the equator to the opposite pole; consequently the long borders of adjacent cells are in juxtaposition, and their pointed extremities meet at points in the axis of the lens (Hoffmann).

Ritter has described short, nucleated cells in the centre of the lens; these are held by Babuchin to be cells which have been arrested in their development.

Fibres from the lens of the frog; after Hoffmann. Magnified 700 times. ]

*e.* The *retina* is the innermost coat of the eye; in the recent state it is pale, soft, and smooth. The structures composing it are arranged in ten layers; from the deeper surface towards the choroid these are: the internal limiting membrane, the optic-fibre layer, the ganglion layer, the inner molecular layer, the inner nuclear layer, the outer molecular layer, the outer nuclear layer, the external limiting membrane, the layer of rods and cones, and the pigment layer.

These layers are held together by connective-tissue elements.

(1) The *internal limiting membrane* (Membrana limitans interna) will be described together with the connective-tissue elements (10).

(2) The *optic-fibre layer* is formed by the fibres of the optic nerve. The nerve-fibres in their course towards the eye are possessed of medullary sheaths, but on piercing the sclerotic these sheaths are lost. The fibres are now pale, non-medullated, and of very varying thickness. In the mass of fibres nothing can be seen except an extremely fine fibrillation and very fine varicosities; the latter, however, appear to be artificial productions (Hoffmann). This layer of fibres extends over the inner surface of the retina, and gradually thins from the point of entrance of the optic nerve to the limits of the retina.

(3) The *ganglion-layer* lies immediately without the nerve-fibre layer (Fig. 258 b). The ganglion-cells are small and usually pear-shaped. The cells possess large nuclei, round which is a thin layer of very granular protoplasm. The cells have inner and outer processes; the inner pass into the nerve-fibre layer, the outer into the inner molecular layer in more or less radiating directions. Manz claims to have traced a direct connection between the inner processes and the fibres of the nerve-fibre layer.

Each ganglion-cell, whatever its shape or size, has only one inner process, which is easily distinguished from the outer process by its being more glistening, by the possession of varicosities, and because this process never branches.

The outer processes are single (Schwalbe) or rarely double (Hoffmann), and have as a rule a direction at right angles to the inner processes. Each outer process is finely granular, which suggests rather a prolongation of the cell-substance than a true process. Frequently they are branched, sometimes forming two equal sized processes, which give off finer twigs; at other times they appear to pass through the whole of the inner molecular layer without undergoing division (Schwalbe). The processes do not inosculate (Santi Sirena).

Vertical section through retina of frog; after Hoffmann. Magnified 500 times.

a Internal limiting membrane. b Ganglion-cell layer. c Internal molecular layer. d Internal nuclear layer. e External molecular layer. f External nuclear layer. g Layer of rods and cones. h Pigmented epithelium layer. 1. Inner segments of rods and cones. 2. Outer segments of rods and cones. 3. Outer transparent segments of pigmented epithelium. ]

(4) The *inner molecular layer* (Fig. 258 c) is 0·07–0·08 mm. thick (Hoffmann), and consists of a finely granular mass together with the outer processes of the ganglion-layer, and connective-tissue elements.

The granular matter consists of an extremely fine network or reticulum, through which numerous fine fibres course (Schultze, Kölliker, Manz, Heinemann, and others); according to Schultze the supposed molecules or granules of others (Henle, Merkel, and Retzius) are simply the fine meshes of this reticulum. The branched, outer processes of the ganglion-cells form a rich anastomosis in this layer.

(5) The *inner nuclear layer* (Fig. 258 d) contains parts of two kinds of cellular elements; these are radial nerve-fibres with large nuclei, and connective-tissue elements (see below, par. 10). The nerve-fibres are easily distinguished by their spindle-shaped varicosities; both cellular elements possess large oval nuclei. The bodies of the cells surrounding the nerve nuclei are almost filled by the nuclei, which have sharply-defined, rounded nucleoli. The fibres to which these cells are attached may be distinguished as inner and outer processes; the inner process is fine, irregularly varicose, and unbranched; the outer process is thicker, finely granular, and is not varicose (Schwalbe). At the margin of the outer molecular layer the outer processes divide, usually into two branches, and at an acute angle to each other, though sometimes at a right angle. The further course of these branches in the outer molecular layer is unknown.

(6) The *outer molecular layer* (Fig. 258 e) corresponds in general with the inner molecular layer as regards its structure; it is, however, much thinner.

(7 and 9) The *outer nuclear layer* and the *layer of rods and cones* (Figs. 258 f, g, 259). The rods and cones are intimately connected with the elements of the outer nuclear layer, hence the two layers are best described together.

The rods (bacilli) have two parts or limbs, an outer and an inner, which differ in structure, and in chemical and physical characters. The outer part is highly refractive, the inner more homogeneous and less refractive, the two parts being sharply differentiated from one another.

The outer part is also weakly doubly refracting, the inner has no trace of this property. The rods are 0·05–0·06 mm. in length, of which 0·035–0·04 mm. belongs to the inner limb. The outer end of the outer limb is more or less rounded; the whole has a longitudinal striation (Schultze), due to its being composed of rounded fibrils, about twenty-four to each rod (Hensen). The fibrils are sharply differentiated from each other and have a slightly spiral course; when seen in transverse section these outer limbs do not appear to be round (Schultze), although others hold them to be perfectly rounded (Hoffmann and others), and that the loss of the cylindrical form is due to the methods of treatment. According to Merkel the longitudinal striation is caused by a canalisation of the outer limb, which according to him encloses the processes of the pigmented epithelial layer; he is also of opinion that the spiral appearance is an artificial product. In the latter opinion he is probably wrong, as perfectly fresh rods examined in aqueous humour show the same spiral appearance (Hoffmann): against the canalisation view others observe that the longitudinal striation is most distinct near the inner limit of the outer limb, and that it is impossible to conceive that the processes of the pigment-cells should terminate with such extremely regular ends (Hoffmann).

Various preparations from the eye of the frog: chiefly from the retina.

1. Rod from retina in aqueous humour, showing spiral striation. 2. Three rods and one cone after treatment with osmic acid. 3, 4, 5. Rods examined in recent state. 6, 7. Inner segments of two rods after treatment with osmic acid. a Outer limb. b Inner limb. c Lenticular body. d Nucleus of outer nuclear layer. e External limiting membrane. 8. Nuclear body from inner nuclear layer. 9. Twin-cone. 10. Sustentacular fibre of retina. 11. Surface view of pigmented epithelium of retina. 12, 13. Isolated pigmented cells of retina. 14. Four pigmented cells, rods and cones, external limiting membrane, and part of outer nuclear layer attached. 15. Two pigmented cells; each showing three attached rods. 16. Muscle-fibre from the iris.

Figs. 1, 2, 3, 4, 5, 6, 7, 8, 9 are magnified 500 times. Fig. 10, 300 times. Fig. 16, 400 times. All are copied from Hoffmann’s figures.

Figs. 12, 13, 14, 15 are copied from Morano’s figures; Hartnack, Oc. II, Obj. 9. ]

In the central part of the inner end of the outer limb is seen a dark point when the structures are examined in transverse section (Ritter, Manz, Schiess, Schultze, and others). The cause of this is not clearly understood; some hold it to be a fibre (Ritter’s fibres), others hold it to be an artificial product (Hensen).

After treatment with certain reagents the outer limbs show a transverse striation, which is probably produced by the action of these reagents on the sheath of the outer limbs; that a sheath is present is proved by its possession of a different refractive index (Zenker, Schultze) to the rest of the outer limb, and this transverse striation is not seen until the whole organ has undergone considerable post-mortem changes (Hoffmann). Should this change be allowed to proceed a stage further, the outer limbs of the rods split transversely and form small discs from 0·0005–0·00055 mm. thick; this takes place in the outer limb only.

The inner segments of the rods (Figs. 258, 259) are short (0·020–0·022 mm.) and of the same thickness as the outer limbs. When perfectly fresh they appear homogeneous; very quickly changes commence, which are probably due to coagulation. A plano-convex figure (Fig. 259) is then seen at the outer portion of the segment (lens-shaped figure of Schultze); with staining reagents it gives the same reactions as the outer segment of the rods. The rest of this segment forms a short cylinder, which probably has no distinct sheath (Hoffmann, Merkel); some observers are inclined to think that a sheath exists (Landolt, Schwalbe).

The outer segments of the rods are of two chief sizes (Schwalbe). Those of the one kind are large; the second variety occurs less frequently, and the segments are shorter, measuring only 0·002 to 0·0025 mm. The inner segment is a long, thread-like process, except where it is swollen to enclose the lens-shaped body.

The rods are much more numerous than the cones, except at one small spot (macula lutea) on the posterior surface of the retina, where only cones are found (Krause).

The cones (coni) have each two segments like the rods (Figs. 258, 259). The outer segments are short (4–5 µ), they are slightly conical and terminate externally in a blunt point; they possess a longitudinal striation (Schultze), and very easily break up transversely into small discs, which, however, do not separate so completely as in the case of the rods, in consequence of the presence of a sheath continuous with a sheath on the inner segment.

The inner segments (Figs. 258, 259) have convex sides and measure 12–14 µ; like the corresponding parts of the rods they possess lens-shaped bodies at their junction with the outer segments, but the bodies differ in shape, being bi-convex or rather oval in form. The inner segments are enclosed in a delicate sheath continuous with that of the outer segments.

In some cases two cones are united to form a twin-cone; in such cases the one is always larger than the other (Fig. 259 9), and has several peculiarities which distinguish it from the smaller.

The smaller or secondary member of a twin-cone is longer, and possesses a lens-shaped body which is plano-convex. The larger or principal member of a twin-cone is shorter, has a plano-convex body, but also an oval, homogeneous, glistening body, which is directly attached to the plano-convex body. The shape of the two members is also different.

The *outer nuclear layer* (Fig. 258 f) is 14–16 µ thick; the nuclei lie in two layers. The nuclei belonging to rods and cones have the same characters, each nucleus being a large, oval, hyaline body, and enclosing a bright nucleolus. Each nucleus is surrounded by an extremely thin layer of finely granular matter. The inner processes of the nuclear bodies both of the rods and the cones extend to the outer molecular layer, are there dilated and serrated, where they become attached to the outer molecular layer (Schultze, Hoffmann). In some cases, however, the inner process of the nuclear bodies, belonging to the rods, forms only a short fine fibre.

In the case of twin-cones the corresponding parts in the outer nuclear layer possess two nuclei (Schultze).

(8) The *pigment layer* (Figs. 258 h, and 259 11, 12, 13, 14, 15) is not intimately attached to the rest of the retina. It consists of cylindrical cells in which two parts or segments are sharply differentiated; the external part, directed towards the choroid coat, is of pale, or colourless granular protoplasm, and occupies one-third of the length of the cell; this part encloses a large, round, nucleolated nucleus. This colourless segment of the cell also includes one or two bright yellow, fat globules (Morano). Seen from the surface the cells are hexagonal (Fig. 259 11). The remaining two-thirds of the cells consists of a brush formed of numerous fine pigmented processes; the ultimate terminations of the processes, which lie parallel to each other, are frequently unpigmented; each cell possesses thirty to forty such processes (Morano).

The processes extend between the rods and cones as far as the external limiting membrane (Figs. 258, 259), or sometimes a little further (Merkel, Morano, Hoffmann). The processes from one pigment-cell surround a number of rods and cones; according to Morano twelve to fifteen rods and cones may be encased or surrounded by the processes of a single cell.

The thickness of this layer varies from 60–70 µ; the nuclei of the cells have a diameter of 10–12 µ, the width of a single cell is from 20–25 µ (Hoffmann).

(10) The *connective-tissue elements* of the retina and the *external* and *internal limiting membranes*. The elements of the retina are supported by connective-tissue elements or sustentacular cells, which have a radial arrangement, and which form the two limiting membranes (Müller).

Each sustentacular cell (Fig. 259 10) has two segments, an inner and an outer, the boundary between these lying in the inner nuclear layer, and being marked by the presence of a large oval nucleus. The inner segment of each cell terminates internally in a wide ‘foot’ or base, or may form several such after having undergone division (Schultze): these bases together form a transparent, thin membrane, the internal limiting membrane (membrana limitans interna).

Within the ganglion-layer these cells possess peculiar appendages, which fit round the ganglion-cells and support them (Schwalbe).

The outer segments of the sustentacular cells extend into the outer molecular layer, and then break up into irregular processes which extend radially to the external limiting membrane, and which they probably form. The external limiting membrane (membrana limitans externa) is therefore a membrane corresponding to the internal limiting membrane, and formed by the flattened ends of the processes belonging to the sustentacular cells.

The sustentacular cells have a distinct, resistant cell-wall (Schwalbe); the cell-contents are a finely granular protoplasm, and a large oval, nucleated nucleus placed in the inner nuclear layer.

*f.* The *ciliary processes* have the same structure as the rest of the choroid coat: the vessels form more or less longitudinal meshes and are more irregular than in the rest of the choroid.

*g.* The *posterior chamber* and *vitreous body* (Fig. 260). The vitreous humour occupies the greater portion of the cavity of the eyeball, i.e. the posterior chamber. The humour consists of a mass of cells enclosed in a transparent hyaloid membrane (membrana hyaloidea), which is in contact with the internal limiting membrane of the retina.

The cells forming this structure are small, flattened, transparent, and nucleated (Iwanoff and Virchow); according to the former observer the cells have contractile powers.

The hyaloid membrane is described as structureless by Schwalbe, as fibrous by Pappenheim, Bowman, and Fuikbeiner.

The vessels of the vitreous body (Fig. 260) are as follows. The A. hyaloidea arises at the lowest point of the corpus ciliare; it almost immediately divides into two branches, which form a ring at a distance of about 0·5 mm. from the lens and lying on the surface of the vitreous body (Fig. 260 I, II). One, R. nasalis, passes to the nasal side and courses through one-fourth of the circle; the other, R. temporalis, courses through three-fourths of the circle. The branches are all given off proximally and at right angles to the circle (Fig. 260 I, II). From the R. nasalis only one branch arises, from the R. temporalis seven, the first of which corresponds in point of origin with the branch from the R. nasalis. The branches on the nasal and temporal surfaces of the vitreous body are the shortest.

The vessels of the vitreous body; after Hans Virchow.

I. Vessels of the vitreous body; seen from the deeper pole and slightly from above. Magnified 6 times.

II. Arteries of the vitreous body of the right eye.

A Seen from the proximal pole. B Seen from the nasal side.

III. Veins of the vitreous body of the left eye.

A Seen from the proximal pole. B Seen from the nasal side.

a Nasal vein. b Temporal vein. c Branch (constant) of temporal vein. n R. nasalis of the ophthalmic artery. t R. temporalis of the ophthalmic artery. t′ Termination of the R. temporalis. V Ventral vein. ]

These branches form a capillary network (Fig. 260 I) with elongated meshes, formed by the capillaries anastomosing at acute angles. The capillary network is more dense towards the middle of the proximal surface than in other parts.

The veins arising from this network are three in number (Fig. 260 III); two of these accompany the arteries from their origin, and form a somewhat similar circle around the lens, while the third passes backwards along the ventral surface of the vitreous body to the papilla nervi optici. The nasal vein, however, takes a more proximal course than the corresponding artery, the branches of which it crosses; consequently the venous ring is not so perfect as the arterial. The nasal vein is larger and the temporal vein smaller than the corresponding arteries.

The ventral vein is formed near the papilla nervi optici by the union of two smaller branches. The capillary system of these vessels has the usual structure of capillaries, the cells being united by cement-substance (Zimmermann).

The blood-vessels of the vitreous body are accompanied by lymphatics; according to Iwanoff they completely enclose the capillaries: Zimmerman contradicts this view, as he has been unable to find lymphatics on that side of the capillaries directed towards the vitreous body.

B. Appendages of the eye.

The appendages of the eye are the eye-muscles (see pp. 55–59), the eyelids, the Harderian gland, and the lachrymal duct.

*a.* The *eyelids* are two in number, an upper and a lower. The upper eyelid is intimately attached to the eyeball and follows the movements of that organ.

The *lower eyelid* (membrana nictitans) is much larger than the upper and has the same functions as the lower eyelid of higher vertebrates. It forms a transparent covering for the eyeball, and is raised by a special muscle (see p. 58); functionally it takes the place of both eyelids of higher vertebrates.

The lower eyelid is a prolongation of the skin, but has only a few pigment-cells, except at its free margin, and no serous glands. Mucous glands are found in two or three rows, closely applied to one another, on the superficial surface of the lid; on the deeper surface they are wanting. The stroma of the lid, like the cutis, is of connective-tissue.

Nerve-fibres can be traced in all directions through the substance of the lid, forming a wide-meshed plexus. Around each gland the plexus becomes finer and by numerous branchings much closer; from the plexus twigs are given off, which divide to form a number of fibrils traceable into the epithelial cells of the glands (Openchowski).

The vessels of the lower eyelid have been investigated by Stricker, (l. c.); according to him they possess some interesting peculiarities. Many of these capillaries course within a lymphatic vessel, in some places the capillary being contracted by a projection from its inner wall; where this is found the accompanying lymphatic is correspondingly dilated. Such points are especially met with where the capillaries branch; in many cases the capillary was contracted to such an extent that the blood-corpuscles were unable to pass the obstruction. Stricker further observed in the living tissue that such constrictions could take place in a part which a short time previously had been comparatively wide and dilated; further, that many of the nerves were enclosed in similar lymphatics. Langer, however (l. c.), describes the vessels as being accompanied by an irregular network of small lymphatic vessels.

Preparations from the nictitating membrane of Rana esculenta to show distribution of nerves.

I. Preparation of the nictitating membrane to show nervous supply to a capillary vessel; after Klein. Hartnack, Oc. III, Obj. 8.

a Capillary vessel. b Blood-corpuscles. c and d Non-medullated nerve-fibres.

II. To show distribution of nerves in the epithelium; after Klein. Hartnack, Oc. IV, Obj. 8.

a} Subepithelial b} nerve-fibres. c Fine fibrils between the deepest epithelial cells. d Deepest epithelial cells. ]

The distribution of the nerves in the lower eyelid has been described by Klein. In the epithelium they form a network resembling that found in the cornea (Fig. 261 II); along the blood-vessels the fine fibrils form a perivascular network, which supplies fine twigs to the walls of the vessels (Fig. 261 I). He distinguishes three kinds of pigmented cells.

*b.* The *Harderian gland* is situated at the inner angle of the eye, and is pear-shaped in form. It consists of a number of racemose glands held together by connective-tissue, the whole being enclosed in a relatively thick and strong capsule of connective-tissue.

The alveoli have a diameter of 0·040–0·060 mm.: they possess a lining of epithelium and a lumen which varies considerably in size. The epithelial layer is bounded externally by a membrana propria. The cells are placed eccentrically, they are cylindrical, and composed of finely granular protoplasm; each cell contains a pale, rounded nucleus. The ducts of the alveoli are lined with a single layer of cylindrical epithelium, the cells of which are usually shorter and narrower than those of the epithelium of the alveoli; the ducts open into a single main tube, lined with similar epithelium but strengthened externally by a layer of connective-tissue. The glands secrete a fluid which moistens the free surface of the eye.

The Harderian glands are surrounded by a rich capillary anastomosis which completely invests the alveoli.

*c.* The *lachrymal duct* opens behind and below into the nasal cavity (see p. 389), anteriorly it can be traced forwards, as a small tube imbedded in connective-tissue and lying immediately beneath the skin, to the outer angle of the eye, where it opens by numerous tubules.

The lachrymal duct is lined with ciliated columnar epithelium.

ADDENDA.

HISTOLOGY OF MUSCLE, CARTILAGE, BONE, AND THE CONNECTIVE TISSUES.

LITERATURE.

I. MUSCLE AND NERVE-ENDINGS IN MUSCLE.

*Arnold, J.*, Gewebe der organischen Muskeln. Stricker’s Gewebelehre, 1871. Vol. I, p. 142.

*Arnold, J.*, Ueber die Abscheidung des indigschwefelsauren Natrons im Muskelgewebe. Virchow’s Arch. Vol. LXXI, p. 1.

*Babuchin*, Ueber den feineren und Ursprung des Axencylinders. Centralbl. f. med. Wiss. 1868, p. 755.

*Barfurth, D.*, Die Rückbildung des Froschlarvenschwanzes und die sogenannten Sarkoplasten. Arch. f. mik. Anat. 1887. Vol. XXIX, p. 35.

*Biedermann, W.*, Zur Lehre vom Bau der quergestreiften Muskelfaser. Wiener Sitzungsber. 1876. Vol. LXXIV, Pt. III, pp. 49–62.

*v. Biesiadecki, A.*, and *Herzig, A.*, Die verschiedenen Formen der quergestreiften Muskelfasern. Wiener Sitzungsber. 1859, Vol. XXXIII, p. 146: and in Moleschott’s Untersuchungen, 1860, Vol. VI, p. 105.

*du Bois-Reymond, E.*, Ueber facettenförmige Endigung der Muskelbündel. Berlin. Acad. Monatsber. 1872, pp. 791–814. Abstract in Centralbl. f. d. med. Wiss. 1873. No. 55, p. 868.

*Bowman.* On the minute structure and movements of voluntary muscle. Phil. Trans. 1840, p. 457.

*Bremer, L.*, Ueber die Endigungen der markbaltigen und marklosen Nerven im quergestreiften Muskel. Arch. f. mik. Anat. 1882. Vol. XXI, p. 165.

*Bremer, L.*, Ueber die Muskelspindeln nebst Bemerkungen über Structur, Neubildung, und Innervation der quergestreiften Muskelfaser. Arch. f. mik. Anat. 1883. Vol. XXII, p. 318.

*Calberla, E.*, Studien über die Entwicklung der quergestreiften Muskeln und Nerven der Amphibien und Reptilien. Arch. f. mik. Anat. 1875. Vol. XI, p. 442.

*Calberla, E.*, Ueber die Endigungsweise der Nerven in den quergestreiften Muskeln der Amphibien. Dissert. Freiburg i. B. 1874; also in Zeitschr. f. d. wiss. Zool. 1874. Vol. XXIV, pp. 164–178.

*Chittenden, R. H.*, Histochemische Untersuchungen über das Sarkolemm und einige verwandte Membranen. Untersuch. d. physiol. Instituts d. Universität Heidelberg. Vol. III.

*Cohnheim, J.*, Ueber die Endigung der Muskelnerven. Centralbl. f. d. med. Wiss. 1863, p. 865.

*Eberth, C. J.*, Untersuchungen über die normale und pathologische Leber. Virchow’s Arch. 1864. Vol. XXXIX, p. 74.

*Engelmann, T. W.*, Zur Lehre von der Nervenendigung im Muskel. Jenaische Zeitschr. 1868. Vol. IV, p. 307.

*Engelmann, T. W.*, Untersuchungen über den Zusammenh. von Nerven u. Muskelfasern. Leipzig, 1863.

*Engelmann, T. W.*, Microscopische Untersuchungen über die quergestreifte Muskelsubstanz. Pflüger’s Arch. 1873. Vol. VII, pp. 33–71, and pp. 155–187.

*Engelmann, T. W.*, Ueber die Endigung der motorischen Nerven in den quergestreiften Muskeln der Wirbelthiere. Centralbl. f. med. Wiss. 1863, p. 289.

*Ewald, A.*, Ueber die Endigung der motorischen Nerven in den quergestreiften Muskeln. Pflüer’s Arch. 1876. Vol. XII, p. 529.

*Ewald, A.*, and *Kühne, W.*, Die Verdauung als histologische Methode. Heidelb. naturhistor.-med. Verhandl. 1877. Vol. I, p. 451.

*Exner, S.*, Notiz zu der Frage von der Faserverteilung mehrerer Nerven in einem Muskel. Pflüger’s Arch. 1885. Vol. XXXVI, p. 572.

*Fischer, E.*, Ueber die Endigung der Nerven im quergestreiften Muskel der Wirbelthiere. Arch. f. mikrosk. Anat. 1877. Vol. XIII, p. 365.

*Froriep, A.*, Ueber das Sarcolemm und die Muskelkerne. Arch. f. Anat. u. Physiol. 1878, p. 416.

*Gerlach, J.*, Ueber das Verhalten der Nerven in den quergestreiften Muskelfäden der Wirbelthiere. Sitzungsb. Erlangen. 1873. Vol. V, p. 97; Abstract in Centralbl. f. d. med. Wiss. 1874, p. 227.

*Gerlach, J.*, Das Verhältniss der Nerven zu den willkürlichen Muskeln der Wirbelthiere. Leipzig, 1874.

*Gerlach, J.*, Ueber das Verhältniss der nervösen und contractilen Substanz des quergestreiften Muskels. Arch. f. mik. Anat. 1877. Vol. XIII, p. 399.

*Golgi, C.*, Sui Nervi dei Tendini dell’ Uomo e di altri Vertebrati e di un nuovo Organo Nervoso terminale Musculo-tendineo. Torino. Estr. dalle Memorie della Reale Acc. di Torino. Series II. 1880, Vol. XXXII.

*Grützner, P.*, Zur Anatomie und Physiologie der quergestreiften Muskeln. Recueil Zoolog. Suisse, 1884. Vol. I, pp. 665–684.

*Haycraft, J. B.*, Upon the cause of the striation of voluntary muscular tissue. Quart. Journ. Micros. Soc. 1881. Vol. XXI, p. 307.

*Hensche*, Ueber die Drüsen und glatten Muskeln in der äusseren Haut von Rana temporaria. Zeitschr. f. wiss. Zool. 1856. Vol. VII, p. 273.

*Hensen, V.*, Ueber die Entwicklung des Gewebes und der Nerven im Schwanze der Froschlarve. Virchow’s Arch. 1864. Vol. XXX, p. 51.

*Jakimovitsch*, Ueber die Regeneration der glatten Muskelfasern. Centralbl. f. d. med. Wiss. 1879, p. 897.

*Key, A.*, Bidrag till Nervernas ändningsätt i Musklerna. Förhandlingar vid Skandinaviska Naturforskaemötet i Stockholm, 1863. Abstract in Centralbl. f. d. med. Wiss. 1866, p. 212. (Muscles of frog’s tongue.)

*Klebs, E.*, Die Nerven der organischen Muskeln. Centralbl. f. d. med. Wiss. 1863, p. 561.

*Klebs, E.*, Die Nerven der organischen Muskeln. Virchow’s Arch. 1865. Vol. XXXII, pp. 169–198.

*v. Kölliker, A.*, Gewebelehre.

*v. Kölliker, A.*, Einige Bemerkungen über die Endigung der Hautnerven u. den Bau der Muskeln. Zeitschr. f. wiss. Zool. 1857, Vol. VIII, p. 311.

*Krause, W.*, Ueber den Bau der quergestreiften Muskelfaser. Zeitschr. f. rat. Med. Vol. XXIII.

*Krause, W.*, Die Nervenendigungen in den Froschmuskeln. Internat. Monatschr. 1884. Vol. I, pp. 194–203.

*Krause, W.*, Die motorischen Endplatten, etc. Hannover, 1869.

*Krause, W.*, Ueber die Endigungen der Muskelnerven. Göttinger Nachrichten. 1863, p. 21.

*Krause, W.*, Ueber die Endigungen der Muskelnerven. Henle and Pfeufer’s Zeitschr. 1863. Vol. XX, pp. 1–19.

*Kühne, W.*, Untersuchungen über Bewegungen und Veränderungen der contractilen Substanzen. Arch. f. Anat. n. Phys. 1859, p. 816.

*Kühne, W.*, Die Muskelspindeln. Virchow’s Arch. 1864. Vol. XXVIII, pp. 528–538.

*Kühne, W.*, Untersuchungen über das Protoplasma und die Contractilität. Leipzig, 1864.

*Kühne, W.*, Ueber die peripherischen Endorgane der motorischen Nerven. Leipzig, 1862.

*Kühne, W.*, Zur Lehre von den Endplatten der Nervenhügel. Virchow’s Arch. 1866. Vol. XXXIV, pp. 412–422.

*Kühne, W.*, Ueber das Verhalten des Muskels zum Nerven. Verhandl. d. natur-hist.-med. Vereins zu Heidelberg. 1880. Vol. II, p. 227.

*Kühne, W.*, Ueber Nervenendigungen in den Muskeln nach Beobachtungen von M. B. van Sykel. Abdruk. aus den Verhandl. d. Naturh. med. Verein zu Heidelberg. 1884. Vol. III, pp. 238–242.

*Kühne, W.*, Wiederlegung der Bemerkung E. du Bois-Reymond’s über mehrfache. Nervenendigungen einer Muskelfaser. Zeitschr. f. Biol. 1884. Vol. XX, pp. 531–539.

*Kühne, W.*, Ueber die Endigung der Nerven in den Muskeln. Virchow’s Arch. 1866. Vol. XXVII, pp. 508–533.

*Kühne, W.*, and *Voit, C.*, Neue Untersuchungen über motorische Nervenendigung. Zeitschr. f. Biologie. Vol. XXXIII.

*Lavdowsky, M.*, Die feinere Struktur und die Nervenendigungen der Froschharnblase. Arch. f. Anat. u. Physiol. 1872, p. 55.

*Leboucq, H.*, Recherches sur le développement et la terminaison des nerves chez les larves des Batrachiens. Bull. de l’Acad. de roy. de Belgique. 1876. Vol. XLI, p. 561.

*Letzerich, L.*, Ueber die Endigungsweise der motorischen Nerven. Med. Centralz. 1863, No. 37.

*Leydig, F.*, Ueber Tastkörperchen und Muskelstructur. Arch. f. Anat. u. Physiol. 1856, p. 150.

*Löwit*, Die Nerven der glatten Muskulatur. Sitzungsb. d. Wiener Acad. 1875. Vol. LXXI, Pt. III, p. 355.

*Marshall, C. F.*, The structure and distribution of striped and unstriped muscle. Quart. Journ. Micros. Sci. 1887. Vol. XXV.

*Martin, H.*, Sur la structure de la fibre musculaire striée et sur les analogies de structure et fonction entre les tissus musculaires et les cellules à bâtonnets (protoplasma strié). Arch. de physiol. norm. et pathol. 1882, p. 465.

*Mayer, S.*, Die sogenannten Sarkoplasten. Anat. Anzeiger, 1886. No. 9, p. 231.

*Mayer, S.*, Einige Bemerkungen zur Lehre von der Rückbildung der quergestreiften Muskelfasern. Prager Zeitschr. f. Heilkde. 1887. Vol. VIII, p. 177.

*Mays, K.*, Histo-physiol. Untersuchungen über die Verbreitung der Nerven in den Muskeln. Zeitschr. f. Biol. Vol. XX.

*Mays, K.*, Ueber die Nervatur des Musculus rectus abdominis des Frosches. Heidelberg, 1886.

*Melland, B.*, A simplified view of the histology of the striped muscle-fibre. Quart. Journ. Micros. Sci. 1885. Vol. XXV, p. 371.

*Merkel, F.*, Der quergestreifte Muskel. Arch. f. mik. Anat. 1873. Vol. IX, pp. 293–367.

*Minra, M.*, Untersuchungen über die motorischen Nervenendigungen der quergestreiften Muskelfasern. Virchow’s Arch. 1886. Vol. CV, p. 129.

*Nasse, O.*, Zur Anatomie und Physiologie der quergestreiften Muskelfasern. Leipzig, 1882. Abstract in Centralbl. f. d. med. Wiss. 1882, pp. 884 and 908.

*Newman, D.*, New theory of contraction of striated muscle and demonstration of the composition of the broad dark bands. Journ. of Anat. and Physiol. 1879, p. 4.

*Nicolaides, R.*, Ueber die caryokynetischen Erscheinungen der Muskelkörper während des Wachstums der quergestreiften Muskeln. Arch. f. Anat. u. Physiol. 1883, p. 441.

*Odenias, M. W.*, Undersökungen öfer de sensibla muskelnervena. Nord. Medic. Arch. Vol. IV, No. 18.

*Paneth, J.*, Die Entwickelung von quergestreiften Muskelfasern aus Sarkoplasten. Wiener Sitzungsber. 1886. Vol. XCII, Pt. III, p. 561.

*Petrowsky*, Zur Frage über das Wachstum der Muskelfasern des Muskelgewebes beim Frosch. Med. Centralbl. No. 49, pp. 769–772.

*Pohl-Pincus*, Ueber die Muskelfasern des Froschherzens. Arch. f. mik. Anat. 1884, Vol. XXIII, p. 500; and Verhandl. der Physiol. Gesell. zu Berlin. 1882–3. No. 9.

*Ranvier, L.*, Appareils nerveux terminaux des muscles de la vie organique; cœurs sanguins, cœurs lymphatiques; œsophagus; muscles lisses. Leçons recueillies par Weber et Lataste. Leçons d’Anatomie générale faites au Collège de France. Paris, 1880. Vol. VII, p. 350.

*Ranvier, L.*, Leçons sur l’histologie du Système nerveux. 1878. Vol. II.

*Reichert, K. E.*, Ueber das Verhalten der Nervenfasern bei dem Verlauf und Endigung in einem Hautmuskel des Frosches, Rana temporaria. Arch. f. Anat. u. Physiol. 1851, p. 29.

*Retzius*, Zur Kenntniss der quergestreiften Muskelfaser. Biologische Untersuchungen. 1881, p. 1.

*Rouget*, Note sur la terminaison des nerfs moteurs dans les muscles chez les reptiles, les oiseaux et les mammifères. Comptes rendus. 1862. LV, p. 548.

*Sachs, C.*, Die quergestreifte Muskelfaser. Arch. f. Anat. u. Physiol. 1872, pp. 607–648.

*Sachs, C.*, Die Nerven der Sehnen. Arch. f. Anat. u. Physiol. 1875, p. 402.

*Sandmann, D. G.*, Ueber die Verteilung der motorischen Nervenendapparate in den quergestreiften Muskeln der Wirbelthiere. Arch. f. Anat. u. Physiol. 1885, p. 240.

*Schönn*, Anatomische Untersuchungen im Bereich des Muskel- und Nervengewebes. Jenaische Zeitschr. 1865. Vol. II, pp. 26–60.

*Schultze, M.*, Ueber Muskelkörperchen und das was man eine Zelle zu nennen habe. Arch. f. Anat. u. Physiol. 1816, p. 17.

*Sokolow, A. A.*, Sur les transformations der terminaisons des nerfs dans les muscles de la grenouille après les section des nerfs. Arch. de Physiol. normale et pathologique, 1874, pp. 300–315.

*Sokolow, A. A.*, Ueber die Nervenendigungen in den Muskeln ausgehungerter Frösche. Medicin. Bote. 1876, St. Petersburg.

*Tergast, P.*, Ueber das Verhältniss von Nerve und Muskel. Arch. f. mik. Anat. 1873. Vol. IX, p. 36.

*v. Thanhoffer, L.*, Beiträge zur Histologie und Nervenendigung der quergestreiften Muskelfasern. Arch. f. mik. Anat. 1882. Vol. XXI, p. 26.

*Thin, G.*, On the structure of muscular fibre. Quart. Journ. Microsc. Sci. 1877. Vol. XVI, pp. 251–259.

*Tolotschinoff*, Ueber das Verhalten der Nerven zu den glatten Muskelfasern der Froschharnblase. Arch. f. mik. Anat. 1869. Vol. V, p. 510.

*Trinchese, S.*, Mémoire sur la terminaison périphérique des nerfs moteurs dans la série animale. Journ. de l’Anat. et de la Physiol. 1867, pp. 485–504 (original in Italian, 1867).

*Tschiriew, S.*, Sur les terminaisons nerveuses dans les muscles striés. Arch. de physiol. norm. et path. 1879. Vol. VI, p. 89.

*Tschiriew, S.*, Sur les terminaisons nerveuses dans les muscles striés. Compt. rend. 1878. Vol. LXXXVII, p. 604.

*Unger*, Untersuchungen über die quergestreiften Muskelfasern des lebenden Thieres. Wiener med. Jahrb. 1879, p. 61; and in Centralbl. f. d. med. Wiss. 1879, No. 34, p. 622.

*Wagener, G. R.*, Ueber die Verbindung von Muskel und Sehne unter einander. Sitzungsber. naturw. Gesells. Marburg. 1874, pp. 38–46.

*Waldeyer, W.*, Ueber die Endigung der motorischen Nerven in den quergestreiften Muskeln. Centralbl. f. d. med. Wiss. 1863, p. 369.

*Waldeyer, W.*, Untersuchungen über den Ursprung und den Verlauf des Axencylinders bei Wirbellosen und Wirbelthieren, sowie über dessen Endverhalten in der quergestreiften Muskelfaser. Henle and Pfeuffer’s Zeitschr. 1864. Vol. XX, pp. 193–257.

*Weismann, A.*, Ueber die Musculatur des Herzens beim Menschen und in der Thierreihe. Arch. f. Anat. u. Physiol. 1861, p. 41.

*Wolff, W.*, Ueber den Zusammenhang des Muskels mit der Sehne. Diss. Berlin, 1877; Abstract in Centralbl. f. d. med. Wiss. 1877, p. 733.

Consult also: *Arnold, J., Kühne, W.*, and *Schweigger-Seidel, F.*, in Stricker’s Handbuch der Gewebelehre.

II. CARTILAGE AND BONE.

*Arnold, J.*, Ueber die Abscheidung des indigschwefelsauren Natrons im Knochengewebe. Virchow’s Arch. 1877. Vol. LXXI, p. 17.

*Arnold, J.*, Die Ausscheidung des indigschwefelsauren Narions im Knorpelgewebe. Virchow’s Arch. 1878. Vol. LXXIII, p. 125.

*Bigelow, W. S.*, Notiz über den Theilungsvorgang bei Knorpelzellen sowie über den Bau des Hyalinknorpels. Arch. f. mik. Anat. 1879. Vol. XVI, p. 457.

*Boll, F.*, Untersuchungen über den Bau und die Entwicklung der Gewebe. Arch. f. mik. Anat. 1871. Vol. VII, p. 275.

*Bruch, C.*, Ueber die Verknöcherung der Wirbelsäule bei den Batrachiern. Würzb. naturw. Zeitschr. 1862. Vol. III, pp. 225–238.

*Bush, F.*, Das Knochengewebe der Batrachier nach den Untersuchungen von N. Kastschenko. Verhandl. d. physiol. Gesells. zu Berlin. 1881, pp. 358–361.

*Flesch*, Untersuchungen über die Grundsubstance des Hyalinknorpels. Würzburg, 1880.

*Heidenhain*, Zur Kenntniss des hyalinen Knorpels. Studien aus d. physiol. Inst. zu Breslau. 1863. Pt. II, p. 1.

*Hertwig, O.*, Anatomisch histologische Untersuchung des Skelets der Mundhöhle und der Zähne der Amphibien; supplement to Vol. XI. Arch. f. mikroskopische Anat. 1874, pp. 29–32.

*Kastschenko, N.*, Ueber die Genese und Architectur der Batrachierknochen. Arch. f. mik. Anat. 1881. Vol. XIX, pp. 1–52.

*Kastschenko, N.*, Ueber die Krappfärbung der Froschgewebe. Arch. f. mik. Anat. 1882. Vol. XXI, p. 357.

*v. Kölliker*, Gewebelehre Leipzig. 1867, p. 66.

*Lehmann, J. C.*, Ueber den Knorpel in der Achillessehne des Frosches. Zeitschr. f. wiss. Zool. 1864. Vol. XIV, p. 109.

*Levschin, L.*, Ueber die Entwicklung des Knochengewebes des Frosches. Centralbl. f. med. Wiss. Nos. 18, 19.

*Mays, C.*, Ueber den Bau der Sehnen, etc. Virchow’s Arch. 1879. Vol. LXXV, p. 112.

*Renaud, M. J.*, Système hyalin de soutènement des centres nerveux et de quelques organes des sens. Arch. de Physiol. 1881, p. 6.

*Schleicher, W.*, Die Knorpelzelltheilung. Arch. f. mik. Anat. 1879. Vol. XVI, P. 248.

*Spina, A.*, Ueber die Saftbahnen des hyalinen Knorpels. Wiener Sitzungsber. 1879. Vol. LXXX, Pt. III, p. 267.

*Stadelmann, E.*, Die Histologie des ‘Pseudoknorpels’ in der Achillessehne des Frosches, etc. Virchow’s Arch. 1880, Vol. LXXX, p. 105; also as Dissert. inaug. Königsberg, 1878.

*van Stricht, O.*, Recherches sur le cartilage hyalin. Annales de la société de médicine de Grand. 1885, pp. 221–232.

*Thin, G.*, On the structure of hyaline cartilage. Quart. Journ. Micros. Sci. 1876. Vol. XVI, pp. 1–22.

*v. Török, A.*, Der feinere Bau des Knorpels des Achillessehne des Frosches. Centralbl. f. d. med. Wiss. 1872, No. 5, p. 66; and Verhandl. d. phys.-med. Gesells. zu Würzburg, 1872, Vol. III, pp. 1–26.

III. THE CONNECTIVE TISSUES.

*Billroth, T.*, Ueber die Epithelzellen der Froschzunge, den Bau des Cylinder- und Flimmerepithel und ihr Verhältniss zum Bindegewebe. Arch. f. Anat. u. Physiol. 1858, p. 159.

*Bizzozero, G.*, Ueber den Bau des Sehnengewebes. Moleschott’s Untersuchungen. 1876. Vol. XI, p. 36.

*Bobinzky, C.*, Zur Kenntniss des Baues, der Entwicklung and der regressiven Metamorphose der Fetzellen. Centralbl. f. d. med. Wiss. 1885. No. 43, pp. 753–755.

*Boll, F.*, Untersuchungen über den Bau und die Entwicklung der Gewebe. Arch. f. mik. Anat. 1871. Vol. VII, p. 276.

*Ciaccio, G. V.*, Nuove Ricerche sull’ interna tessitura dei tendi. Memorie dell’ Academie delle scienze dell Istituto di Bologna, 1872. Series III, Vol. II. Abstract in Centralbl. f. d. med. Wiss. 1873.

*Czumak, J.*, Notiz über elastische Sehnen. Centralbl. f. med. Wiss. 1863, p. 785.

*Flemming, W.*, Ueber Bildung und Rückbildung der Fettzelle im Bindegewebe; und Bemerkungen über die Structur des letztern. Arch. f. mik. Anat. 1871. Vol. VII, p. 32.

*Gerlach, J.*, Ueber Bindegewebe. Sitzungsb. d. phys.-med. Societät zu Erlangen. 1872, p. 78.

*Ginsburg, L.*, Ueber das Verhalten der Sehnenzellen bei der Entzündung. Virchow’s Arch. 1882. Vol. LXXXVIII, p. 263.

*Golgi, C.*, Sui Nervi dei Tendini dell’ Uomo e di altri Vertebrati e di un nuovo Organo nervoso terminale Musculo-tendineo. Estr. dalle Memorie della Reale Acc. di Torino. 1880. Series II, Vol. XXXII, p. 29; No. 6, p. 86.

*Hensen, V.*, Ueber die Entwicklung des Gewebes und der Nerven im Schwanze der Froschlarve. Virchow’s Arch. 1864. Vol. XXXI, p. 51.

*Hoyer*, Ueber den Bau der Cylinder- und Flimmerepithelien und ihr Verhältniss zum Bindegewebe. Arch. f. Anat. u. Physiol. 1858, p. 163; also Deutsche Klinik. 1857, No. 21.

*Iwanoff, A.*, Beiträge zur normalen und pathologischen Anatomie des Frosch-Glaskörpers. Centralbl. f. d. med. Wiss. 1868, p. 129.

*Kollmann*, Ueber den Bau der Sehne. Münchener Sitzungsber. 1878. Abstract in Centralbl. f. d. med. Wiss. 1879, p. 881.

*Maddox*, On the apparent relation of nerve to connective-tissue corpuscles. Proc. Roy. Soc. Lond. 1868. Vol. XVI, p. 61.

*Mays, C.*, Ueber den Bau der Sehnen mit besondere Berücksichtigung über Saftbahnen. Virchow’s Arch. 1879. Vol. LXXV, p. 112.

*Sachs, C.*, Die Nerven der Sehnen. Arch. f. Anat. u. Physiol. 1875, p. 402.

*Spina, A.*, Untersuchungen des lebenden Bindegewebes. Oesterr. med. Jahrb. 1884. Pt. II.

NOTE BY THE TRANSLATOR.

Reference has already been made to the views of Messrs. Melland and Marshall on the structure of muscle-fibres. The opinion that the striation of voluntary muscle is wholly or in part due to the presence of a regularly arranged network was previously published by Retzius, Bremer, and others. The authors referred to have now for the first time shown the importance of this network in all vertebrate muscular tissues, whether voluntary or involuntary.

Mr. Marshall gives the following summary of the result of his researches, which the Translator has confirmed by his own observations:--

1. In all muscles which have to perform rapid and frequent movements, a certain portion of the muscle is differentiated to perform the function of contraction, and this portion takes on the form of a very regular and highly modified intracellular network.

2. This network, by its regular arrangement, gives rise to certain optical effects which cause the peculiar appearances of striped muscle.

3. The contraction of the striped muscle-fibre is probably caused by the active contraction of the longitudinal fibrils of the intracellular network; the transverse networks appear to be passively elastic, and by their elastic rebound cause the muscle to rapidly resume its relaxed condition when the longitudinal fibrils have ceased to contract; they are possibly also paths for the nervous impulse.

4. In some cases where muscle has been hitherto described as striped, but gives no appearance of the network on treatment with the gold and other methods, the apparent striation is due to optical effects caused by a corrugated outline in the fibre.

5. In muscles which do not perform rapid movements, but whose contraction is comparatively slow and peristaltic in nature, this peculiar network is not developed. In most if not all of the unstriped muscles of invertebrates there does not appear to be an intracellular network present in any form, but in the unstriped muscle of vertebrates there are longitudinal fibres only; these possibly represent a form of network intermediate between the typical irregular intracellular network of other cells and the highly modified network of striped muscle.

6. The cardiac muscle-cells contain a network similar to that of ordinary striped muscle.

DESCRIPTION OF THE FIGURES ON PLATE II.

Fig. 180 (p. 278).

I. Preparation of the mucous membrane of the dorsal surface of the mouth and oesophagus to show the vascular supply. Arteries red, veins blue; after Schöbl.

II. Small portion of the above to show the dilatations on the capillaries; after Schöbl.

Fig. 187 (p. 285).

Transverse section through the mucous membrane of the fundus of the stomach of Rana esculenta. Alcohol preparation, doubly stained with carmine and anilin blue. After Biedermann. (Oc. II, Syst. 7, Hartnack.)

Fig. 196 (p. 298).

I. Partial injection of the liver from the portal vein (blue): Rana esculenta.--G. H.

II. Partial injection of the liver from the hepatic vein (red): Rana esculenta.--G. H.

III. Complete injection of the liver from the hepatic artery (red) and from the portal vein (blue): Rana esculenta.--G. H.

A Portal (interlobular) veins and their branches. B Hepatic (intralobular) veins and their branches. C Hepatic arteries and their branches.

Fig. 208 (p. 318).

Two sections from the lung of Rana temporaria; stained with borax-carmine.--G. H.

I. The lung dilated (Hartnack, Oc. I, Syst. 3).

II. The lung contracted (Hartnack, Oc. I, Syst. 7).

A Band of muscle cut transversely. B Band of muscle cut longitudinally. C Muscular layer of surface.

Fig. 217 (p. 334).

Portions of two transverse vertical sections through the kidney.--G. H.

I. Kidney of Rana esculenta, partial injection of the uriniferous tubes with silver nitrate (Hartnack, Oc. I. Syst. 7).

II. Kidney of Rana temporaria, stained with borax-carmine (Hartnack, Oc. I, Syst. 7).

Fig. 219 (p. 337).

Two portions from a gold preparation of the kidney of Rana esculenta.--G. H.

I. Showing the tendency to split into lobules.

II. Nerve-fibres accompanying the blood vessels.

a Blood-vessels. b Nerves.

APPENDIX.

I. WORKS WHICH DESCRIBE ORGANS OR SETS OF ORGANS IN THE FROG.

*Bettade, E.*, Sulle diverse forme delle R. temp. in Europa e più particolammente nell’ Italia. Venezia, 1885.

*Brehm, A. C.*, Illustriertes Thierleben. Hildburghausen, 1869. Vol. V.

*Burdon-Sanderson*, Handbook for the Physiological Laboratory. London, 1873.

*Camerana, L.*, Recherches sur les variations de in R. esculenta et du Bufo viridis dans le bassin de la Méditerranée. Paris, 1883.

*Carus, C. G.*, Lehrbuch der vergleichenden Zootomie. 2nd Edit. Leipzig, 1834.

*Cepède, Comte de la*, Histoire naturelle des quadrupèdes ovipaires et des serpens. Paris, 1808.

*Dugès*, Recherches anatomiques et physiologiques sur les Reptiles. Ext. des Annales des Sciences naturelles. Paris, 1827.

*Duméril and Bibron*, Erpétologie générale ou histoire complète des Reptiles. 1836.

*Ecker, A.*, Icones physiologicae. Leipzig, 1851–1859.

*Fatio, V.*, Faune des vertébrés de la Suisse. Genève et Bâle, 1872.

*Gegenbaur, C.*, Grundzüge der vergl. Anatomie. Leipzig, 1870.

*Gegenbaur, C.*, Grundriss der vergl. Anatomie. Leipzig, 1878.

*Gerlach*, Handbuch der Histologie. 1853–1854.

*Gesner, C.*, Historia Animalium. Liber I. 1551.

*Gesner, C.*, Icones Animalium. 1560.

*v. Griesheim, A.*, Ueber die Zahlenverhältnisse der Geschlechter bei R. fusca. Pflüger’s Arch. f. d. ges. Physiol. 1881. Vol. XXVI, p. 3.

*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs. Vol. VI, Amphibien. Leipzig, 1873–1878.

*Howes, G. B.*, An Atlas of Practical Elementary Biology. London, 1885.

*Huxley, T.*, Anatomy of the Vertebrated Animals. London, 1871.

*Huxley, T.*, Lectures on the Elements of Comparative Anatomy.

*Huxley, T.*, Article Amphibia, Encyclopaedia Britannica. IXth Edit. 1875.

*Klein, E.*, Beiträge zur Anatomie der ungeschwänzten Batrachier. Jahreshefte. Württemberg, 1850, pp. 1–84.

*Klein, E.*, and *Noble Smith*, Atlas of Histology. London, 1879–1880.

*Kloezke, C. G.*, Dissertatio anatomica de Rana cornuta. Berolini, 1816.

*v. Kölliker, A.*, Handbuch der Gewebelehre. 5th Edit. Leipzig, 1867.

*Kuhl, H.*, Beiträge zur Zoologie der Rana esculenta: in Beitr. z. Zool. Frankfurt a. M., 1820.

*Laurenti, J. N.*, Synopsis Reptilium. Viennae, 1768.

*Leydig, F.*, Lehrbuch der Histologie. Frankfurt a. M., 1857.

*Marshall, A. M.*, The Frog. 3rd Edit. London and Manchester, 1888.

*Mayer, A. F.*, Beiträge zu einer anatomischen Monographie der Rana pipa. Acad. Caes. Leop. Nov. Acta, 1825. Vol. XII, p. 527.

*Meckel, J.*, Beiträge zur vergleichenden Anatomie. Leipzig, 1811.

*Meckel, J.*, System der vergleichenden Anatomie. Halle, 1833.

*Mivart, St. Geo.*, On the Classification of the Anurous Batrachians. Proc. Zool. Soc. 1869.

*Mivart, St. Geo.*, The Common Frog. London, 1874.

*Müller, J.*, Beiträge zur Anatomie und Naturgeschichte der Amphibien. Tiedemann’s Zeitschr. 1831, p. 190.

*Müller, J.*, The Physiology of the Senses, etc. Translated by W. Baly. London, 1848.

*Owen, R.*, Anatomy of the Vertebrates. London, 1866.

*Ranvier, L.*, Leçons d’anatomie générale. Paris, 1880.

*Rösel v. Rosenhof*, Historia naturalis ranarum nostratium. Nürnberg, 1758.

*Rudolphi and Breyer*, Observationes anatomicae circa abricam Ranae pipae. Berolini, 1811.

*Rusconi, M.*, Développement de la grenouille commune. Milan, 1826.

*Schneider, J. G.*, Historia amphibiorum. Jenae, 1799.

*Schwalbe, G.*, Lehrbuch der Anatomie der Sinnesorgane. Erlangen, 1885.

*Stannius, H.*, Zootomie der Amphibien (Handb. der Zoot. der Wirbelthiere, 2 Buch). 2nd Edit. Berlin, 1856.

*Stricker, S.*, Beiträge zur Biologie der Batrachier. Wien. Zool. Bot. Verhandl. 1866. Vol. XVI, pp. 451–456.

*Stricker, S.*, Handbuch der Gewebelehre.

*Stricker, S.*, Manual of Human and Comparative Histology. Translated by H. Power. London, 1870.

*Swammerdam, J.*, Biblia Naturae Amstelodamensis. (Dutch and Latin by Gaubius. Leidae, 1738.)

*Todd and Bowman*, The Physiological Anatomy and Physiology of Man. London, 1845–1857.

*Vogt, C.*, Zoologische Briefe. Frankfurt a. M., 1851.

*Wagler, J.*, Natürliches System der Amphibien. München, Stuttgart, and Tübingen, 1830.

*Wagner, R.*, Lehrbuch der vergleichenden Anatomie. Leipzig, 1834–1835.

*Wagner, R.*, Icones Zootomicae. Leipzig, 1841.

*Wagner, R.*, Handwörterbuch der Physiologie. 1842.

*Waters, W. H.*, Histological Notes. Manchester and London, 1884.

*Wiedersheim, R.*, Lehrbuch der vergleichenden Anatomie der Wirbelthiere. 2nd Edit. Jena, 1886.

*Wiedersheim, R.*, Elements of Comparative Anatomy of Vertebrates. Translated by N. Newton Parker. London, 1886.

II. WORKS RELATING TO THE EMBRYOLOGY AND DEVELOPMENT OF THE FROG.

*Balfour, F. M.*, Treatise on Comparative Embryology. London, 1880.

*Born, G.*, Beiträge zur Bastardirung zwischen den einheimischen Anurenarten. Pflüger’s Arch. f. d. ges. Physiol. 1883. Vol. XXXII, p. 453.

*Durham, H. E.*, Note on the presence of a Neurenteric Canal in Rana. Quart. Journ. Micros. Sci. 1886. Vol. XXVI, p. 509.

*Giles, A. E.*, The development of the fat-bodies in Rana temporaria. Quart. Journ. Micros. Sci. 1888. Vol. XXIX.

*Goette, A.*, Kurze Mittheilungen aus der Entwicklungsgeschichte der Unke. Arch. f. mik. Anat. 1873. Vol. IX, p. 396.

*Goette, A.*, Entwicklungsgeschichte der Unke. Leipzig, 1875.

*Hertwig, O.*, Die Entwicklung des mittleren Keimblattes der Wirbelthiere. Jena, 1883.

*Johnson, A.*, and *Sheldon, L.*, Notes on the Development of the Newt (Triton cristatus). Quart. Journ. Micros. Sci. 1886. Vol. XXVI, p. 573.

*Marshall, A. M.*, The Frog: An Introduction to Anatomy, Histology, and Embryology. 3rd Edition. Manchester and London, 1888.

*Pflüger, E.*, Einige Beobachtungen zur Frage über die das Geschlecht bestimmenden Ursachen. Pflüger’s Arch. f. d. ges. Physiol. 1881. Vol. XXVI.

*Pflüger, E.*, Hat die Concentration des Samens einen Einfluss auf das Geschlecht? Pflüger’s Arch. f. d. ges. Physiol. 1883. Vol. XXIX, p. 1.

*Pflüger, E.*, Zusammenstellung der Ergebnisse und Erörterung der Principien der Zeugung. Pflüger’s Arch. f. d. ges. Physiol. 1883. Vol. XXXII, p. 542.

*Pflüger, E.*, and *Smith, W. J.*, Experimente über Bastardirung der anuren Batrachier. Pflüger’s Arch. f. d. ges. Physiol. 1883. Vol. XXXII, p. 519.

*Remak*, Untersuchungen über die Entwickelung der Wirbelthiere. Berlin, 1855.

*Schultze, O.*, Zur ersten Entwickelung des braunen Grasfrosches. Leipzig, 1887.

*Schultze, O.*, Die Entwicklung der Keimblätter und der Chorda dorsalis von Rana fusca. Zeitschr. f. wiss. Zool. 1888. Vol. XLVII, p. 325.

*Spencer, W. B.*, Some Notes on the Early Development of Rana temporaria. Quart. Journ. Micros. Sci. 1885. (Supplement.)

*Stricker, S.*, Untersuchungen über die Entwicklung des Kopfes der Batrachier. Arch. f. Anat. u. Physiol. 1864, p. 52.

*Törok, A.*, Beiträge zur Kenntniss der ersten Anlagen der Sinnesorgane und der primären Schädelformation bei den Batrachiern. Moleschott’s Untersuchungen, 1870. Vol. X, p. 338.

III. ADDITIONS TO THE LISTS GIVEN AT THE HEADS OF THE SECTIONS.

1. THE BONES.

*Albrecht, P.*, Note sur le basi-occipital des batraciens anoures. Extr. d. Bullet. d. Musée royal d’hist. nat. de Belgique. 1883. Vol. II.

*Born, G.*, Die sechste Zehe der Anuren. Morphol. Jahrb. 1876. Vol. I.

*Born, G.*, Ueber das Skelet des Fersenhöckers von Rana fusca, etc. Sitzungsb. d. Schles. Gesell. f. vaterländ. Cultur. 1879.

*Born, G.*, Nachträge zu Carpus und Tarsus. Morph. Jahrb. 1880. Vol. VI.

*Ecker, A.*, Icones physiologicae. Leipzig, 1881–1889.

*Ecker, A.*, Die Anatomie des Frosches. 2nd Edition. Braunschweig, 1888, pp. 17–62.

*Gegenbaur*, Untersuchungen zur vergl. Anatomie der Wirbelsäule bei Reptilien und Amphibien. Leipzig, 1862.

*Gegenbaur*, Grundzüge der vergl. Anatomie. Leipzig, 1870.

*Goette, A.*, Brustbein und Schultergürtel auf entwickelungsgeschichtlicher Grundlage verglichen bei Amphibien und Anurioten. Arch. f. mik. Anat. 1877. Vol. XIV, p. 502.

*Howes, G. B.*, On some abnormalities of the Frog’s vertebral column. Anat. Anz. 1886. Vol. I, Pt. II.

*Leydig, F.*, Ueber den Bau der Zehen bei Batrachiern und die Bedeutung des Fersenhöckers. Morphol. Jahrb. 1876. Vol. II.

*Parker, W. K.*, A monograph on the structure and development of the shoulder-girdle and sternum. Ray. Soc. 1867.

*Schneider, J. G.*, Historia amphibiorum. Jenae, 1799.

*Stöhr, P.*, Zur Entwickelungsgeschichte des Anurenschädels. Zeitschr. f. wiss. Zool. 1881. Vol. XXXVI.

*Törok, A.*, Beiträge zur Kenntniss der ersten Anlagen der Sinnesorgane und der primären Schädelformation bei den Batrachiern. Moleschott’s Untersuchungen. 1870. Vol. X, p. 338.

2. THE MUSCLES.

*Albrecht, P.*, Beitrag zur Morphologie des M. omohyoides und der ventralen inneren Interbranchial-Musculatur. Inaug. Dissert. Kiel, 1876.

*Ecker, A.*, Die Anatomie des Frosches. 2nd Edition. Braunschweig, 1888, pp. 65–139.

*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs. Vol. VI. Amphibien. Leipzig, 1873–1878.

*Howes, G. B.*, An Atlas of Practical Elementary Biology. London, 1885.

3. NERVOUS SYSTEM.

*Engelmann, T. W.*, Ueber die Discontinuität des Axencylinders und den fibrillären Bau der Nervenfasern. Pflüger’s Arch. f. d. ges. Physiol. 1880. Vol. XXII, p. 1.

*Grandry*, Recherches sur la structure interne du cylindre de l’axe et des cellules nerveuses. Bull. de l’Acad. Roy. du Belgique. 1868.

*Hodge, C. F.*, Some effects of stimulating ganglion-cells. (Some anatomical details regarding the relations of nerve-fibres with nerve-cells are given.) American Journ. of Phys. 1888.

*Owsjannikow, P.*, Ueber die Rinde des Grosshirns. Mémoires de l’acad. impériale des sciences de St. Pétersbourg. 1879. Series VII, Vol. XXVI, No. 11.

*Spiro*, Physiologisch-topographische Untersuchungen am Rückenmark des Frosches. Mémoires de l’acad. impériale des sciences de St. Pétersbourg. 1870. Series VII, Vol. XVI, No. 7.

*Waldeyer, W.*, Untersuchungen über den Ursprung und Verlauf des Axencylinders. Henle u. Pfeuffer’s Zeitschr. 1864. Vol. XX, pp. 193–257.

Consult also: *Gerlach, J.*, *Mayer, S.*, and *Schultze, M.*, in Stricker’s Handbuch der Gewebelehre.

4. THE VASCULAR SYSTEM.

*Barthol, P.*, Sopra il sistema linfatico dei Rettili. Pavia, 1833.

*Blaschek, A.*, Untersuchungen über Herz, Pericard, Endocard, und Pericardhöhle. Schenk’s Mitt. 1885. New Series, p. 32.

*Eberth, C. J.*, in Stricker’s Handbuch der Gewebelehre.

*Klein, E.*, On the peripheral distribution of non-medullated nerve-fibres (nerves of the blood-vessels in the frog’s tongue). Quart. Journ. Micros. Sci. 1872. Vol. XII, p. 123.

*Mayer, S.*, Studien zur Histologie und Physiologie des Blutgefässsystems. Wiener Sitzungsb. 1886. Vol. XCIII, Pt. III, p. 45.

*v. Recklinghausen, F.*, (The lymphatics) in Stricker’s Handbuch der Gewebelehre.

*Rollett, A.*, (The Blood) in Stricker’s Handbuch der Gewebelehre.

*Teichmann, L.*, Untersuchungen über das Saugadersystem. Leipzig, 1861.

5. THE ALIMENTARY CANAL.

*Heidenhain, R.*, Beiträge zur Kenntniss des Pancreas. Pflüger’s Arch. f. d. ges. Physiol. 1875. Vol. X, p. 557.

*Krause, W.*, Anatomische Untersuchungen (Tongue). Hannover, 1861.

Consult also: *Klein, E.*, The Oral Cavity and the Oesophagus; *Müller, W.*, The Spleen; *Eberth, C. J.*, The Liver, in Stricker’s Handbuch der Gewebelehre.

6. THE LUNGS AND LARYNX.

*Holmgren, F.*, Methode zur Beobachtung des Kreislaufs in der Froschlunge. Beitr. z. Anat. u. Physiol. Festgabe f. C. Ludwig. Leipzig, 1874.

*Meckel, J. F.*, Beiträge zur Geschichte des Respirations-Systemes der Amphibien. Meckel’s Arch. 1849. Vol. V.

*Schmidt, C.*, De l’épithelium pulmonaire. 1866.

*Williams*, Article Respiration, in Todd’s Cyclopaedia of Anat. and Physiol. 1859. Vol. V.

7. THE URINO-GENITAL SYSTEM, THE ADRENALS, AND THE FAT-BODIES.

*Aeby, C.*, Ueber glatte Muskelfasern im Ovarium und Mesovarium von Wirbelthieren. Arch. f. Anat. u. Physiol. 1859, p. 675.

*Giles, A. E.*, The development of the fat-bodies in Rana temporaria. Quart. Journ. Micros. Sci. 1888. Vol. XXIX.

*Grohe, F.*, Ueber die Bewegung der Samenkörper. Virchow’s Arch. 1865. Vol. XXXII, p. 416.

*Virchow, R.*, Ueber die Dotterplättchen bei den Fischen und Amphibien. Zeitschr. f. wiss. Zool. 1849. Vol. IV.

Consult also: *Eberth, C. J.*; *v. La Valette St. George*; *Ludwig, C.*; *Grünwald*; *Obersteiner, H.*; and *Stricker, S.*, in Stricker’s Handbuch der Gewebelehre.

8. THE SKIN AND SENSE-ORGANS.

a. The Skin.

*Busch, A.*, Phänomene aus dem Leben der Pigmentzellen. Arch. f. Anat. u. Physiol. 1856, p. 415.

b. Special Organs of Tactile Sensation.

*Mitrophanow, P.*, Zur Entwicklungsgeschichte und Innervation der Nervenhügel der Urodelenlarven. Biologisches Centralb. 1887, p. 174.

c. The Organs of Taste.

*Beale, L. S.*, New Observations upon the Minute Anatomy of the Papillae of the Frog’s Tongue. Phil. Trans. 1865. Vol. CLV, p. 443.

*Engelmann, T. W.*, in Stricker’s Handbuch der Gewebelehre.

*Maddox, R. L.*, A Contribution to the Minute Anatomy of the Fungiform Papillae and terminal arrangement of Nerve to striped Muscular Tissue in the Tongue of the common Frog. Monthly Micros. Journ. 1869, p. 1.

d. The Ear.

*Albrecht, P.*, Sur la valeur morphologique de la trompe d’Eustache. Communication faite à la Société d’Anatomie Pathologique de Bruxelles. 1884.

*v. Kölliker*, Handbuch der Gewebelehre. 5th Edit. Leipzig, 1867.

*Leydig, F.*, Handbuch der Histologie. Frankfurt a. M., 1857.

*Rüdinger*, in Stricker’s Handbuch der Gewebelehre.

e. The Nose.

*Marshall, A. M.*, Morphology of the Vertebrate Olfactory Organ. Quart. Journ. Micros. Sci. 1879. Vol. XIX, p. 330.

f. The Eye.

*Ciaccio, G. V.*, Beobachtungen über den inneren Bau des Glaskörpers im Auge des Menschen und der Wirbelthiere im Allgemeinen. Moleschott’s Untersuchungen, 1870. Vol. X, p. 383.

*Hannover* and *Finkbeiner*, Vergleichende Untersuchungen der Stärke des Glaskörpers bei den Wirbelthieren. Zeitschr. f. wiss. Zool. 1855. Vol. VI, p. 335.

*Hirschberg, J.*, Zur Dioptric und Ophthalmologie der Fish- und Amphibienaugen. Arch. f. Anat. u. Physiol. 1887, p. 493.

*Ranvier, L.*, Le mécanisme de la Sécrétion. Leçons faites au Collége de France en 1886–1887. (Nictitating membrane.)

Consult also: *Rollett* and *Stieda*, in Stricker’s Handbuch der Gewebelehre.

INDEX.

Abducens nerve, p. 171. " nucleus, 146. Acetabulum, 48. Acromial, 39. Adrenals, 348. Ala magna, 25. " temporalis, 25. Alar cartilages, 28. Alimentary canal, 258. Ampulla anterior, 396. " external, 398. " posterior, 398. Angulo-splenial, 34. Ankle, 50. Anterior ampulla, 396. " brachial lymph-sac, 259. " brachio-radial septum, 258. " brachio-ulnar septum, 258. " chamber, 409. Aorta dorsal, 233. Aponeurosis plantaris, 105. Arachnoid, 162. Arteria basillaris, 163. " bulbi, 222. " circumflexa genu. lat. sup., 238. " " " " inf., 238. " " " med. sup., 238. " " " " inf., 238. " comm. ant., 163. " coraco-clavicularis, 231. " costo-cervicalis, 231. " cruris inf., 239. " cut. calcanei, 239. " cut. fem. med., 237. " " " post., 237. " " pectoris, 231. " haemorrhoid. inf., 236. " lobi hemisph. inf. ext., 163. " " " sup. int., 163. " " optici, 163. " malleol. lat., 240, " malleol. med., 240. " pharyngo-maxill., 230. " ramus auricularis, 228, 230. " " maxillaris comm., 228. " " " inf., 230. " " " sup., 228. " " orbito-nasalis, 228. " scapularis post., 232. " " sup., 232. " spinalis ant., 163. " subscapularis, 232. " suralis, 239. Arteries, 222. " of brain, 162. " of choroid, 411. " of foot, 240. " of hyaloid, 421. " of iris, 413. " of skin, 376. " of vitreous body, 421. Artery, ant. palatine, 224. " " tibial, 239. " brachial, 232. " carotid, 224. " ciliary, 226. " coeliaco-mesenteric, 233. " femoral, 236. " gastric, 233. " haemorrhoidal, 235. " hepatic, 298. " hyaloid, 226. " iliac, 235. " internal carotid, 225. " laryngeal, 226. " lingual, 224. " lumbar, 235. " mesenteric, 234. " occipital, 228. " occipito-vertebral, 226. " oesophageal, 226. " ophthalmic, 225, 411, 413. " peroneal, 231. " pharyngeal, 224. " post. palatine, 224. " radial, 232. " renal, 333. " sciatic, 236. " spermatic, 236. " subclavian, 231. " tibial, 238. " ulnar, 233. " urino-genital, 235. " vertebral, 226. " vesico-epigastric, 235. Articular processes, 17. Articulations of vertebrae, 19. " of atlas, 24. Arytenoid cartilages, 313. Astragalus, 50. Atlas, 18. Auditory nerve, 172. Auditory nucleus, 144. Auerbach’s plexus, 292. Auricles, 214. Auriculo-ventricular valves, 216. Axillary septum, 258. Axis-cylinder, 202.

Bidder’s ganglion, 220. Bile-ducts, 298. Bladder, gall-, 295, 299. " urinary, 338. Blood, 262. Bones and joints, 13. Bowman’s glands, 387. Brachial nerve, 183. Brachio-ulnar lymph-sac, 259. " radial " , 259. Brain, 141.

Calcaneum, 50. Calcified cartilage, 15. Canales coccygei, 21. Canalis vertebralis, 20. " rami ant. acustici, 393. Capitulum radii, 43. Capsule of labyrinth, 391. " of lens, 413. Carotid arch, 222. " gland, 223. Cartilage, calcified, 15. " of shoulder-girdle, 40. " of skull, 29. Cartilages of larynx, 312. " of nose, 27, 385. Cauda equina, 135, 189. Cava recto-vesicalis, 304. Cavitas sigmoidea maj., 43. Central canal of cord, 137. " group of cells, 139. Cerebellum, 148. Cerebral hemispheres, 156. Chamber, anterior, 409. " posterior, 420. Chiasma, optic, 153, 155, 167. Chorda dorsalis, 20. Chordae tendineae, 216. Choroid coat, 409. " plexus of fourth vent., 142, 164. " " third " , 153, 164. Ciliary nerves, 169. " processes, 420. Circulus iridis major, 413. Clavicle, 39. Cloaca, 347. Columella auris, 25, 390. Commissura anterior, 159. " inferior, 140. " posterior, 159. " superior, 140. " transversa, 154. Common bile-duct, 296. Cones, 418. Conus medullaris, 135. Coracoid, 39. Coracoid foramen, 39. Cornea, 406. Corpora quadrigemina, 152. Corpus callosum, 158, 159. " striatum, 158, 159. Corpuscles of blood, 263. " of Hassall, 321. Coverings of brain and cord, 162. Cranial nerves, 141, 167. Cranium, 23. Cricoid cartilage, 312. Crista acustica, 397. " deltoidea, 41. " medialis, 42. Crusta, petrosa, 279. Cupula terminalis, 398. Cutaneous glands, 372. Cuticula dentis, 279. Cutis, 369. Cystic duct, 295.

Dentale, 35. Dentary, 34. Dentine, 279. Descemet’s membrane, 407. Dorsal lymph-sac, 255. " roots, 140. " septum, 252. Duct, common bile-, 296. " cystic, 295. Ductus choledocus, 296. " endolymphaticus, 398. " fenestra ovalis, 394. " perilymphaticus, 395. " Wirsungianus, 301. Dura mater, 162.

Ear, 389. Enamel, 279. Enlargements of cord, 133, 137. Epicoracoids, 37. Epidermis, 367. Epiglottis, 317. Episternum, 36. Epithelium of ventricles, etc., 160. Exoccipitals, 23. External limiting membrane, 420. Extrastapedial, 26, 390. Eye, 405. Eyelids, 422.

Facial nerve, 171. Fat-bodies, 348. Femoral lymph-sac, 260. Fibrae arcuatae cerebelli, 149. Fibres of brain, 161. Filiform papillae, 380. Filum terminale, 135. Foramen condyloideum, 24. " magnum, 23. " Monroi, 157. " ovale, 24. " parietale, 156. " rotundum, 392. Formatio reticularis, 140. Fossa condyloidea, 24. " tympanica, 24. Fourth ventricle, 142. Fronto-parietal bones, 26. Fungiform papillae, 380.

Gall-bladder, 295, 299. Ganglia of bladder, 340. " of heart, 220. " of spinal, 177. Ganglion ciliare, 168. " condyloideum, 173. " Gasserii, 168. " interpedunculare, 152. " layer, 415. " nervi vagi, 173. Gasserian ganglion, 168. Glands, Bowman’s, 387. " cutaneous, 372. " gastric, 285. " Harder’s, 424. " intermaxillary, 280. " Lieberkühn’s, 288. " nasal, 386. " oesophageal, 283. " of nictitating membrane, 423. " periganglionic, 180. " thymus, 320. " thyroid, 322. Glossopharyngeal nerve, 172. Goblet-cells, 289. Goll’s columns, 140. Grey matter, 139.

Hair-cells of ear, 404. " of nose, 388. Harder’s glands, 424. Hassall’s corpuscles, 321. Heart, 213, 214. " endothelium, 320. " muscle, 216. " nerves, 219. " structure of, 216. Hepatic arteries, 421. " portal system, 248. " veins, 297. Hip-joint, 49. Humerus, 41. Hyaloid artery, 421. " membrane, 421. Hyoid, 35. Hypoglossal nerve, 182.

Ilia, 47. Iliac lymph-sac, 257. " septum, 253. Inferior femoral septum, 259. " sinus, 383. Infundibulum, 153. Inguinal septum, 254. Inner molecular layer, 415. " nuclear " , 416. Interfemoral lymph-sac, 260. Intermaxillary glands, 280. Intermediate fem. septum, 259. Internal ear, 391. " limiting membrane, 414, 420. " muscles of eye, 413. Interstapedial, 25, 391. Intestine, 286. Intumescentia ant. and post., 135. Iris, 412. Ischia, 48.

Kidney, 332. Knee-joint, 50.

Labyrinth membranous, 395. " osseous, 391. " structure, 402. Lachrymal duct, 387. Lagena cochlea, 400. Lamina fusca, 411. " suprachoroidea, 411. " terminalis, 153, 157. Large intestine, 292. Laryngeal nerve, 175. Larynx, 311. Lateral group of cells, 139. " lymph-sac, 255. " sense-organs, 379. " sinus, 380. Lens, 413. Lieberkühn’s glands, 288, 293. Ligament. calcanei, 19. " coronarium, 303. " gastro-duodenale, 305. " hepato-duodenale, 287, 295, 305. " intercruralia, 19. " interspinalia, 19. " pectinatum iridis, 409. " suspensor. hepatis, 304. " verteb. comm. ant., 19. " " " post., 19. Limiting membrane, external, 420. " " internal, 414, 420. Lips, 275. Literature on adrenals, 330. " " alimentary canal, 268. " " blood, 211. " " blood-vessels, 205. " " bones and joints, 13. " " cartilage, 431. " " connective tissues, 432. " " ear, 356. " " embryology, 436–437. " " eye, 360. " " fat-bodies, 330. " " gall-bladder, 272. " " general, 435–436. " " heart, 205. " " intestine, 270. " " larynx, 309. " " liver, 272. " " lungs, 309. " " lymph, 211. " " lymphatic system, 209. " " mouth, 268. " " muscle structure, 427. " " muscles, 54. " " nervous system, 122. " " nose, 357. " " pancreas, 272. " " peritoneum, 274. " " respiratory system, 309. " " skin, 353. " " spleen, 273. " " taste-organs, 356. " " thymus, 310. " " thyroid, 310. " " touch-organs, 356. " " urino-genital system, 326. Liver, 294. " cells, 298. " pigment of, 299. " vessels of, 297. Lower eyelid, 422. " nasal glands, 386. Lungs, 317. Lymph, 264. Lymph-hearts, 261, 264. Lymph-sacs of ant. extremity, 258. " " of hinder extremity, 259. " " of trunk, 251, 255, 264. Lymphatic system, 251.

Macula lutea, 419. Malpighian bodies of kidney, 334. " " of spleen, 303. Mandible, 34. Maxillary bones, 32. " septum, 253. Meckel’s cartilage, 35. Mediostapedial, 25, 390. Medulla oblongata, 142. Medullary segments, 202. " sheath, 201. Medullated nerves, 201. Meissner’s plexus, 291. Membrana choriocapillaris, 411. " limitans ext., 420. " " int., 414, 420. " nictitans, 58, 422. " suprachoroidea, 411. Membrane of Descemet, 407. Membranous labyrinth, 395. Mentomeckelian cartilage, 35. Mesocephalic ganglion, 168. Metacarpus, 46. Metatarsus, 52. Meynert’s fibres, 155. Molecular layer, inner, 415. " " outer, 419. Motor-oculi, 167. Mouth, 275. Movements of hand, 46. Mucous glands of skin, 375. Müller’s fibres, 420. Muscle, histology, 433. Muscles, 53. Muscles of abdomen, 67. " " back, 71. " " cloaca, 347. " " eye, external, 55. " " " internal, 413. " " face, 59. " " foot, 105. " " forearm, 84. " " forelimb, 75. " " hand, 87. " " hinder limb, 94. " " hyoid, 64. " " larynx, 315. " " lower jaw, 60. " " skin, 119. Musc. abduct. dig. I brev., 114. " " " II " , 92. " " " " long., 91. " " " V, 113. " " " V brev., 116. " " " I long., 110. " " " II " , 86. " " " V prim., 91. " " " V secund., 91. " " hallucis, 109. " " pollicis, 87. " " brev., 114. " adduct. brev., 100. " " dig. I long., 109. " " " II, 89. " " " V, 113. " " longus, 99. " " magnus, 99. " " pollicis, 87. " anconaei, 87. " antibrachii lat., 85. " " med., 85. " " prof., 85. " biceps fem., 96. " coccygeo-cutaneus, 120. " " -iliacus, 74. " coccygeo-sacralis, 73. " compressor cloacae, 348. " constrictor aditus laryngis, 315. " constrictor iridis, 413. " coraco-humeralis, 82. " cucullaris, 71. " cutaneus dorsi, 119. " " pectoris, 119. " dilator aditus laryngis, 315. " deltoideus, 82. " depressor maxill. inf., 60. " " palpebrae inf., 58. " dilator iridis, 413. " " narium, 59. " extensor brevis, 106. " " carpi ulnaris, 86. " " cruris brevis, 104. " " digit. I brev., 114. " " " " long., 114. " " " II brev., 114. " " " " long., 114. " " " " prop. brev., 92. " " " " " long., 92. " " " III brev., 115. " " " " long., 115. " " " " prop., 93. " " " IV, 116. " " " " brev., 116. " " " " prop., 93. " " " V brev., 115. " " " " long., 115. " " " " comm. brev., 91. " " " " " long., 87. " " dorsi com m., 73. " flex. antibrach. lat. superf., 85. " " " med., 85. " " " prof., 85. " " brev. digit. I, 100. " " " " IV, 112. " " " " V, 113. " " carpi radialis, 84. " " " ulnaris, 84. " " digit. comm., 85, 87. " " " I, II, 108. " " " II brev., 89. " " " II long., 88. " " " II prop., 110. " " " II tert., 89. " " " III brev., 89. " " " III long., 89. " " " III prop., 111. " " " III, IV, V, 107. " " " IV brev., 90. " " " " long., 90. " " " " prop., 112. " " " V brev., 90. " " " " long., 90. " " " " prop., 113. " " metacarp. digit. III, 90. " " " " IV, 90. " " metatars. digit. II, 110. " " " " III, 111. " " metatars. digit. IV, 112. " " phal. prop. dig. III, 112. " " " " " IV, ant., 113. " " " " " IV, post., 113. " " " " " V, 90. " " " " , 113. " " tarsi ant., 104. " " " post., 114. " gastrocnemius, 102. " genioglossus, 66, 281. " geniohyoideus, 64. " glutaeus, 94. " hyo-arytenoideus anterior, 315. " " posterior, 315. " hyoglossus, 66, 281. " ilio-fibularis, 96. " ilio-lumbaris, 74. " ilio-psoas, 101. " infraspinatus, 79. " intercrurales, 75. " interossei, 93, 113. " " dorsales, 116. " interscapularis, 78. " intertransversar. cap. sup., 75. " " " " inf., 75. " " " dorsi, 75. " lateralis narium, 60. " latissimus dorsi, 72. " levator ang. scap., 76. " " bulbi, 57. " longissimus dorsi, 72. " lumbricales, 108. " masseter, 62. " nasalis ext., 60. " obliquus ext., 67 " " inf., 56. " " int., 67. " " sup., 56. " obturat., 182. " omohyoideus, 65. " opponens dig. I, 110. " " " II, 89. " " " V, 90. " palmaris brev., 87. " pectineus, 100. " pectoralis, 80. " petrohyoideus ant., 65. " petrohyoidei post., 66, 315. " plantaris, 107. " protrahens scap., 76. " pterygoideus, 61. " pyriformis, 95. " quadratus fem., 112. " rectus abdom., 67. " " extern. bulbi, 55. " " fem. ant., 95. " " infer. ", 55. " " inter. ", 55. " " intern. major, 97. " " super. ant., 56. " " intern. minor, 98. " retractor bulbi, 56. " sartorius, 97. " semimembranosus, 97. " semitendinosus, 100. " sphincter ani, 347. " sternohyoideus, 64. " sternomastoideus, 76. " sternoradialis, 82. " submaxillaris, 62. " submentalis, 63. " subscapularis, 78. " temporalis, 61. " tibialis ant., 104. " " post., 103. " transverso-scapularis major, 77. " " " minor, 77. " transversus metacarp., 93. " " plant., 108. " triceps femoris, 95. " vastus ext., 96. " " int., 96.

Nasal bones, 33. " cartilages, 385. " glands, 403. Nephrostomes, 336. Nerve, abducens, 171. " auditory, 172. " brachial, 183. " facial, 171. " fifth spinal, 187. " fourth spinal, 188. " glossopharyngeal, 172. " hypoglossal, 182. " laryngeal, 175. " oculo-motor, 167. " olfactory, 167. " optic, 167, 405. " pathetic, 142, 168. " palatine, 169. " peroneal, 195. " pneumogastric, 173. " radial, 186. " sixth spinal, 188. " spinal, 175. " structure of, 201. " sympathetic, 197. " third spinal, 188. " tibial trigeminal, 168. " vagus, 173. Nerves, 167. " of Cornea, 408. " " ear, 403. " " heart, 219. " " lungs, 319. " " oesophagus, 286. " " skin, 378. " " stomach, 286. Nervi ciliares, 169. Nervus coccygeus, 189. " coraco-clavicularis, 183. " cruralis, 189. " cut. antibrach. inf., 185. " cut. antibrach. sup., 185. " cut. dorsi pedis lat., 196. " ileo-hypogastricus, 189. " peroneus, 195. " " comm. inf., 196. " " lateralis, 196. " " medialis, 196. " ramus accessorius, 174. " " anterior, 173. " " auricularis, 172. " " cardiacus, 175. " " cut. axillaris, 183. " " cutaneus dors., 174. " " " cruris lat., 196. " " " " med., 194. " " " " post., 194. " " " fem., 189. " " " lat., 187. " " " med., 186. " " " sup., 186. " " dorsalis, 185. " " gastricus, 175. " " hyoideus, 172. " " hyomandibularis, 172. " " laryngeus, 175. " " lateralis, 185. " " mandibularis, 170. " " maxillaris, 170. " " maxillo-mandibularis, 170. " " muscularis, 187. " " ophthalmicus, 169. " " palatinus, 171. " " pectoralis, 185. " " posterior, 173. " " pulmonalis, 175. " " scapularis, 174. " " subscapularis, 185. " " ulnaris lat., 186. " " " med., 185. " tibialis, 194, 195. Neurilemma, 201. Nictitating membrane, 422. Non-medullated fibres, 202. Nose, 383. " skeleton, 27, 383, 385. Nuclear layer, inner, 416. " " outer, 416. Nucleus abducens, 146. " auditory, 144. " centralis, 144. " magnus, 147, 152. " medullae oblongatae, 144. " pneumogastric, 146. " trigeminal, 145.

Oculo-motor nerve, 167. " nucleus, 151. Oesophageal glands, 283. Oesophagus, 282. Olfactory nerve, 167. Omosternum, 36. Operculo-angulare, 35. Operculum, 25. Optic chiasma, 153, 155, 167. " commissure, 154. " fibre layer, 414. " lobes, 149. " nerve, 167, 405. " tracts, 152. Os articulare, 35. " capitato-hamatum, 45. " cuboideum, 51. " cuneiformia, 52. " en ceinture, 27. " lunatum, 44. " multangulum maius, 45. " " minus, 45. " naviculare of foot, 51. " " of hand, 45. " occipitale basilare, 23. " " superius, 23. " pyramidale, 44. Ostium abdominale, 304, 345. Outer nuclear layer, 416. Ovaries, 344. Oviducts, 304, 345.

Palatine artery, 224. " bones, 33. " nerves, 169. Pancreas, 300. Papilla acustica lagenae, 400. Papillae of skin, 370. " of tongue, 380. Parasphenoid, 26. Pars basilaris cochleae, 400. " commissuralis, 147, 152. " media, 135. " neglecta, 400. " peduncularis, 143, 152. Partes condyloideae, 23. Pathetic nerve, 142, 168. Pectoral lymph-sac, 255. " septum, 253. Pelvis, 47. Pericardium, 213. Periganglionic glands, 180. Perilymphatic space, 393. Perineal septum, 253. Peritoneum, 303. Phalanges of foot, 52. " " of hand, 47. Pia mater, 162. Pigment of cerebellum, 149. " " cord, 141. " " hemispheres, 160. " " liver, 299. " " medulla, 148. " " optic lobes, 152. " " thalamencephalon, 155. " " skin, 369. Pigment-layer, 419. Pineal body, 155. Pituitary body, 154, 156. Plexus, Auerbach’s, 292. " lateralis, 165. " Meissner’s, 291. Pneumogastric nerve, 146, 173. " " nucleus, 146. Pons Varolii, 149. Portal systems, 247. " vein, 297. Posterior chamber, 420. Pre-arytenoid cartilages, 314. Precoracoid, 40. Premaxillary bones, 33. Processes, articular, 17. " spinous, 17. " transverse, 17. Processus coracoideus, 40. " coronoideus, mandible, 34. " " " radio-ulnar, 43. " mastoideus, 24. " zygomaticus, 30. Prootic bones, 24. Pterygoid bones, 31. Pubes, 49. Pulmo-cutaneous arch, 230. Pulp-cavity, 279. Purkinge’s cells, 148.

Radio-ulnar, 43. Rami communicantes, 181, 199. Rana aquatica, 3. " esculenta, 4. " flaviventris, 7. " gibbosa, 3. " innoxia, 3. " oxyrhinus, 7, 9. " rubeta, 3. " temporaria, 7. Receptaculum seminis, 337. Recessus utriculi, 396. Remak’s ganglion, 220. Renal arteries, 333. " portal vein, 332. " veins, 333. Reproductive organs, 341. Retina, 414. Retinal pigment, 419. Ritter’s fibres, 418. Rods and cones, 416. Roots of spinal nerves, 175. Round bundle, 154, 159.

Saccus endolymphaticus, 395, 398. " fenestra ovalis, 395. " perilymphaticus, 395. Sacrum, 19. Scapula, 37. Sciatic artery, 236. " nerve, 192. " plexus, 191. Sclerotic coat, 405. Semicircular canal, ant., 396. " " ", ext., 398. " " ", post., 398. Septa, of lymph-sacs, 252. Septum medium, 139. Serous glands of skin, 372. Shoulder-girdle, 37. " -joint, 42. Sinus, superior, 383. Sinus venosus, 214. Skeleton, 15. " of nose, 27, 383, 385. Skin, 367. Skull, 21. Small intestine, 286. Sphenethmoid, 27. Spinal cord, 135. " ganglia, 177. " nerves, 135, 175, 181. " roots of, 175. Spinous processes, 17. Spleen, 302. Squamosal bones, 30. Sternum, 36. Styloid cartilage, 25. Submaxillary lymph-sac, 255. Substantia reticulosa, 138. Sulcus longitud. inf., 135. " " sup., 135. Superior sinus, 383. Supplemental toe, 5, 47, 374. Supra-femoral lymph-sac, 260. " " septum, 259. Suprascapula, 37. Suprastapedial, 26, 390. Suspensorium, 30. Sylvian aqueduct, 150. Sympathetic system, 197. Symphysis pubis, 48. Systemic arch, 226.

Tactile sensation, organs, 377. Taste-organs, 380. Teeth, 278. Tegmentum vasculosum, 395, 402. Temporary papillae, 370. Testis, 341. Thalamenoephalon, 153. Thalamus-tubercinereum strand, 154, 155, 159. Third ventricle, 153. Thymus gland, 320. Thyroid gland, 322. Tibio-femoral septum, 260. Tibio-fibula, 49. Toes, 5, 47, 374. Tongue, 280. Tonsils, 323. Touch-corpuscles, 379. " -spots, 378. Transverse processes, 17. Trigeminal nerve, 168. " nucleus, 145. Trochlear nerve, 168. Truncus arteriosus, 216. Tuberculus maius, 42. Tympanic membrane, 389. " ring, 26. Tympanum, 389, 390.

Upper nasal gland, 386. Ureters, 337. Urinary bladder, 338. " organs, 332. Uriniferous tubes, 334. Urino-genital system, 330. Urostyle, 21. Utricle, 396.

Vagus, 173. Valvula cerebelli, 148. Vasa efferentia, 341. " recta, 412, 413. Vein, anterior abdominal, 248. " " caval, 241. " " orbital, 245. " " tibial, 250. " brachial, 246. " cardiac, 249. " caval anterior, 241. " " posterior, 246. " cutaneous, 244. " dorso-lumbar, 248. " external jugular, 241. " facial, 245. " femoral, 249. " gastric, 249. " haemorrhoidal, 249. " hepatic, 247, 297. " hepatic portal, 249. " iliac, 247. " innominate, 242. " internal jugular, 243. " intestinal, 249. " jugular, external, 241. " " internal, 243. " lingual, 241. " mandibular, 242. " median orbital, 243. " nasal, 245. " ophthalmic, 412. " orbital anterior, 245. " " median, 243. " " posterior, 245. " ovarian, 247. " oviducal, 248. " portal, 297. " posterior caval, 246. " posterior orbital, 245. " pulmonary, 241. " radial, 246. " renal, 247, 333. " renal portal, 332. " sciatic, 247, 250. " spermatic, 247. " splenic, 249. " subclavian, 244. " subscapular, 244. " ulnar, 246. " vertebral, 244. Veins, 241. Vena bulbi anterior, 222. " " superior, 412. " " posterior, 222. " spinalis anterior, 164. " " posterior, 165. " " superior, 164. Ventral lymph-sac, 255. Ventral nucleus, 155. " septum, 252. Ventricle of heart, 215. Ventricles of brain, 153. " of larynx, 316. Vertebrae, 16. " structure of, 20. Vertebral column, 16. Vessels of brain, 162. " of liver, 297. Vitreous body, 420. Vocal cords, 315. " sacs, 320. Vomerine teeth, 276. Vomers, 34.

Webs, 5, 275. Wrist-joint, 45.

THE END.

The Anatomy of the Frog.

Plate I.

University Press Oxford. ]

The Anatomy of the Frog.

Plate II.

University Press Oxford. ]

TRANSLATIONS OF FOREIGN BIOLOGICAL MEMOIRS.

*The Physiology of Nerve, of Muscle, and of the Electrical Organ.* Edited by J. BURDON-SANDERSON, M.D., F.R.SS. L. & E., Waynflete Professor of Physiology in the University of Oxford. Medium 8vo., cloth, price 21s.

II.

*The Anatomy of the Frog.* By Dr. ALEXANDER ECKER, Professor in the University of Freiburg. Translated, with numerous Annotations and Additions, by GEORGE HASLAM, M.D.; and profusely Illustrated.

III.

*Contributions to the History of the Physiology of the Nervous System.* By Professor CONRAD ECKHARD. Translated by Miss EDITH PRANCE. In Preparation.

IV.

*Essays upon Heredity and Kindred Biological Problems.* By Dr. AUGUST WEISMANN, Professor in the University of Freiburg-in-Breisgau. Authorised Translation edited by EDWARD B. POULTON, M.A., F.L.S., F.G.S., Tutor of Keble College, Lecturer in Natural Science, Jesus College, Oxford; SELMAR SCHÖNLAND, PH.D., Sub-Curator of the Fielding Herbarium in the University of Oxford; and ARTHUR E. SHIPLEY, M.A., F.L.S., Fellow and Lecturer of Christ’s College, and Demonstrator of Comparative Anatomy in the University of Cambridge. Medium 8vo., cloth, price 16s.

Oxford

AT THE CLARENDON PRESS

LONDON: HENRY FROWDE

OXFORD UNIVERSITY PRESS WAREHOUSE, AMEN CORNER. E.C.

*Spelling corrections*:

brev → brevis deltoides → deltoideus Duges → Dugès entricles → ventricles evator → levator Labratoire → Laboratoire longitudina → longitudinal Ponicaré → Poincaré resistent → resistant respectiveyl → respectively Thanoffer → Thanhoffer Tranverse → Transverse Trevianus → Treviranus

*Spelling inconsistencies*:

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