CHAPTER X. The Degenerate Cranium

THE DEGENERATE CRANIUM

The cranium or skull is a development in part of the vertebræ or bones forming the backbone, and in part of dermal or membranous bones, which of old in reptiles, as in the alligator to-day, formed the protective armour of the skin of the head. As the head end of the spinal cord of the lancelet developed, the cartilage enclosing it developed to protect it. This was the earlier evolution. Later, another skull developed in connection with this. The cranium or skull therefore has, as Minot remarks, a double origin, or, rather, there are two skulls which were originally distinct. In evolution from the lowest fish to the highest mammal, and in the embryonic development of man, these become united.

The primary skull, as already stated, is practically an extension of the vertebræ, which send side outgrowths to cover the brain as the backbone covers the spinal cord. This primary skull extended in front of the notochord (the spinal cord of the human embryo, and the permanent spinal cord of the lancelet), where it gave off two trabeculæ cranii or front skull plates. Behind, the primary skull or chondrocranium gives off two occipal or rear skull plates. It gives off also two plates midway between the trabeculæ and occipitals, which, as they gradually enclose the primitive hearing apparatus, the otocysts (permanent in fish, and embryonic in man), are called periotic capsules. This primary skull is at first cartilaginous, as in sharks. With the increase in the size of the brain in evolution and in human embryology, this cartilaginous primary skull became insufficient to roof over the brain, and thus resulted gaps in it. The fontanelles, or soft places at the top, sides, and back of the head of the new-born child, are the remains of this failure of the chondrocranium, or primary skull, to cover the gains of the nervous system in the struggle for existence. This deficiency, resultant on advance in evolution, would have been a long-standing serious block to further advance, were it not that the skin of the mammal retained a function inherited from the reptiles and bony fish.

These cavities were filled by dermal bones, which, at first serving merely as armour in the skin of the head, came to be protectors of the nervous system. The following bones represent these dermal bones in the embryonic human skull: The frontals, which form the chief part of the forehead; the sutures, or dovetails, of these normally disappear in the adult, so that the forehead seems to be but one bone. This union may not occur (Fig. 7), as in the case of the philosopher Kant, who had a frontal suture all his life. The dovetails are replaced by solid bone, through a process called synostosis. In the case of the frontal bone it is normal, and in the line of advance. Elsewhere in the skull it is often an expression of defect which may give rise to various cranial states which are either absolutely degenerate in type or degenerate only when occurring in certain races. The parietals and interparietals are also dermal bones which are united by synostosis to form the parietals or side bones of the normal adult skull. The nasal bones which, together with the vomer, form the nose, are likewise dermal bones, and so are the pterygoids and palatines. The maxillaries and præmaxillaries, which, with the mandibles, form the jaws, are dermal bones. The mandibles, however, are in part derived from the chondrocranium.

With rise in evolution, and during the progress of human embryonic development, these bones become fewer through their early gristly union or their synostosis. The openings in the skull resultant on the deficiencies in the chondrocranium are larger in the sauropsida (birds and reptiles) than in the ichthyopsida (amphibious and fish); in the monotremata (egg-laying mammals) than in the sauropsida; in the marsupials (pouched mammals) than in the monotremata, and in the higher mammals than in the marsupials. The development of the brain therefore depends on the growing and expanding power of the secondary skull formed by the dermal bones. These, considered as bones, are degenerate from the high type of the vertebræ, and are a mere reminiscence of that outer skeleton whereby early fish and reptiles emulated the lobster. The influence of any check to development such as produces degeneracy, is exerted first on the development of the bone itself, and finally on the relation to other bones by dovetailing.

In accordance with the general laws governing growth, deficiency in one place is apt to result in increase elsewhere. The brain-protective function of the dermal bones being later in development than their old armour function, is apt to be checked by degeneracy in two ways; in the first the bone does not grow in size or sufficiently to unite with its fellows, or this growth occurs only for the benefit of the bone itself, through Spencer's law of individuation, so that union with the other bones occurs too early for the benefit of the organism as a whole. To the factors underlying this is due the non-increase in intellect after puberty which occurs in the higher apes, and in some of the lower races of men.

These checks also tend to the nutritional benefit of the older primary skull, whence result the irregularities in development that constitute so many of the stigmata of the degenerate cranium. The sutures sometimes do not form because sufficient gristle is not produced to fill the gaps. (Fig. 8.) These secondary gaps are often filled by new dermal bones called Wormian. Sometimes this deficiency coexists with too early synostosis elsewhere.

Degenerate skulls have therefore been divided from the standpoint of these various unions (by synostosis or otherwise) and non-unions of the sutures, on the principle that premature synostosis of a suture produces shortness of the diameter, perpendicular to the direction of the obliterated suture. The bones stop growing prematurely at the seat of the synostosis, but the unaffected borders continue growing. The following types result on this principle:

I. Simple macrocephaly (largeness of head). (a) Hydrocephaly (water in the head. Fig. 9.) (b) Kephalones (all heads. Fig. 10), without hydrocephaly. These two conditions result from the inability of the dermal bones to fill at the proper period the gaps in the chondrocranium. Neither of these denotes complete intellectual degeneracy on the one hand, nor vast intellect on the other. Cuvier was a case of healed-up hydrocephalus, whence his large brain and skull. In a case of kephalones observed by Kiernan there was a brain-weight of 68 ounces. The patient was an imbecile, practically unteachable. Both these conditions denote deep degeneracy, which, however, may find expression elsewhere than in the moral sense or intellect.

II. Simple microcephaly (smallness of head. Fig. 11) or nannocephaly (dwarf head). As a rule these are found among idiots, but much has been done by training, even for them. Many seemingly great intellects, however, have heads approaching, if not reaching this type. Des Cartes, Foscolo, and Schumann had sub-microcephaly. The poet Shelley had a head belonging very nearly to this category, but while he exhibited many stigmata of degeneracy, that of intellectual deficiency was wanting. This type of skull, however, is usually associated with deep degeneracy. It represents in man the condition underlying the premature suture-closing which occurs in the ape. It sometimes may exist with considerable intellect, as in the case of Donizetti. Sometimes this suture-closing directly prevents brain growth. This condition is rarer than many surgeons admit, but it does occur, as witness the cases of Vico, Malebranche, and Clement VI. The fact that these three fractured their skulls in infancy saved them from being imbeciles and idiots like their brothers, sisters, and cousins.

III. Dolichocephaly (long-headedness. Fig. 12). (a) Upper middle synostosis. (1) Simple dolichocephaly is due to synostosis of the sagittal, or antero-posterior suture of the skull. Whether this be due to degeneracy or not depends entirely on the race in which it occurs. The ultra-dolichocephaly of Daniel O'Connell was due, in Kiernan's opinion, to his birth in an Irish district settled by dolichocephalics. Undoubtedly dolichocephaly is tending to mesocephaly (medium size of head). Even the negro, generally regarded by ethnologists as dolichocephalic, is tending in this direction, as numerous observations of my own show. Dolichocephaly, however, while it does not demonstrate, suggests degeneracy, since it seems to be a disappearing type of skull. The changes in American families in this particular indicate this. (2) Sphenocephaly (wedge-shape of head. Fig. 13) is due to synostosis of the sagittal suture, with compensatory growth in the region of the large fontanelle. (b) Dolichocephalic states, resulting from inferior lateral synostosis are: (1) Leptocephaly (narrowness of head), due to synostosis of the frontal and sphenoid bones. (2) Klinocephaly (saddle-shaped head) is due to synostosis of the parietal bones with the greater wings of the sphenoid, or of the parietal with the squamous portion of the temporal bone.

IV. Brachycephaly (shortness of head. Fig. 14). The pure type like pure dolichocephaly is not necessarily by itself evidence of degeneracy, as it may represent race. It is, however, a disappearing type of skull, and hence should lead to critical examination. In the case of the philosopher Kant his ultra-brachycephaly could not be charged to race, since he sprang from dolichocephalic Scotch on one side and dolichocephalic Germans on the other. (a) Posterior stenosis. (1) Pachycephaly (thickness of head) is due to synostosis of the parietal bone with the occipital. (2) Oxycephaly (sugar-loaf head) is due to synostosis of the parietal bones and the occipital with compensatory growth of the region of the anterior fontanelle; a variety of this is acrocephaly (spire head). (b) Upper, anterior, and lateral synostosis. (1) Platycephaly (flat head. Fig. 15), or chæmacephaly, is due to extensive synostosis of the temporal bones with the parietal. Kant, in addition to his cranial stigmata, had this condition. (2) Trochocephaly (roundness of head) is due to partial synostosis of the frontals and parietals in the centre of the coronal suture. (3) Plagiocephaly (wry head. Fig. 16) is due to unilateral synostosis of the frontal and parietal bones. (c) Brachycephaly due to inferior medium synostosis. Simple brachycephaly is due to early synostosis of the nasal and sphenoid.

To these should be added kyphocephaly (lump head), due to synostosis of the posterior part of the squamous portion of the temporal and the parietal bones with Wormian bones in the lambdoid fissure. Tapeisocephaly (low head) is due to synostosis of the great wings of the sphenoid with the frontal. Scaphocephaly (boat-shaped head. Fig. 17) was a term applied by Von Baer to skulls which are very narrow and compressed at the sides, and in which there is no trace of the sagittal suture, but its region is so elevated that the skull cap has the form of a keel boat bottom upward. Trigonocephaly (triangular head) is a variety of scaphocephaly in which depression occurs in place of the keel. Sir Walter Scott had a skull in which premature closure of the sagittal suture produced the appearance of scaphocephaly, but compensation for this elsewhere produced a decidedly different type. Scott presented neurotic phenomena during youth, albeit the brain disease from which he died had anything but a degenerate origin.

Morton and Catlin claim that while the artificial distortions of the cranium may play a part in developing synostosis these have no effect upon the intellectual functions. It has been stated further that there are no mental data to show the effect of artificial malformation of the child's head during development. Frederick Peterson expresses the opinion that this practice only exists among the lower races of mankind. In this he is in decided error, since, as Barnard Davis pointed out many years ago, the practice is far more widespread than is usually suspected. It was common all over Europe, was practised by the Turanians, by the Slaves, by the Scandinavians, Anglo-Saxons, and Celts. Less than half a century ago Foville proved that the nurses in Normandy were still giving children's heads a sugar-loaf shape by bandages and a tight cap. In Britanny they preferred to press it round. In those districts Foville found that not only congenital cranial irregularities of all types, but epilepsy, idiocy, and insanity were exceedingly frequent. As customs like these survive in folklore long after the original superstition which gave them birth, it is exceedingly probable that such crop out in descendants of these races to the present day, to confront the anthropologist with some remarkable crania. Tylor is of opinion that without respecting the repressive action of the Government, the Bretons and Normans secretly continue this practice. Despite the labours of Foville these people openly defied the Government for ten years.

Certain conditions of the occiput have been described as associated with degeneracy. As Obici and Dei Vecchio have shown, the occipital condyle, in man normally convex, abnormally varies between two extremes, the flat and angular condyles. The flat condyle indicates a degenerative type. In the angular condyle the anterior face is derived from that portion of the basi-occipital nucleus that normally takes part in the formation of the anterior condyle region; the posterior face forms the embryonal germ of the occipital.

The occipital of the adult is the final outcome of the fusion of an uncertain number of vertebræ. The occipital bone in man is practically made up of five bones, union between which does not occur completely until the fifth or sixth year. The deficiencies in the chondrocranium appear in the occipital bone, which requires a small portion of the dermal bone to complete it on each side.

The variability of the occipital bone which, as just shown, is so frequently associated with all forms of degeneracy, is still better understood when we remember that it is of vertebral character. The investing mass of the head and of the notochord is the skeleton of the occipital bone. Between this skeleton and the pituitary body the important portion of the brain formed by the occipital lobes takes its origin. As these lobes are practically, as Spitzka has shown, the great centres of sense and other inter-associations it is not astonishing that their imperfect development should be accompanied by changes in the occipital bone. As Crochley Clapham, Mickle, and Spitzka have shown, a flat occiput is common in imbecility and moral insanity. It has been found quite frequently in "reasoning maniacs" by Campagne. The proper development of the occiput influences the proper development of association tracts which serve as a balance wheel to the individual. The proper development of the occipital bone is, moreover, connected with the proper development of the two last vertebræ, which like it are losing their vertebral characteristics.