CHAPTER XIV. Death and Dissolution of the Organism

DEATH AND DISSOLUTION OF THE ORGANISM

1. It is an old saying that we cannot understand life unless we understand death. The dead body, if its temperature is not too low and if it contains enough water, undergoes rapid disintegration. It was natural to argue that life is that which resists this tendency to disintegration. The older observers thought that the forces of nature determined the decay, while the vital force resisted it. This idea found its tersest expression in the definition of Bichat, that “life is the sum total of the forces which resist death.” Science is not the field of definitions, but of prediction and control. The problem is: first, how does it happen that as soon as respiration has ceased only for a few minutes the human body is dead, that is to say, will commence to undergo disintegration, and second, what protects the body against this decay while the respiration goes on, although temperature and moisture are such as to favour decay?

The earlier biologists had already raised the question why it was that the stomach and intestine did not digest themselves. The hydrochloric acid and the pepsin in the stomach and the trypsin in the intestine digest proteins taken in in the form of food; why do they not digest the proteins of the cells of the stomach and the intestine? They will promptly digest the stomach as soon as the individual is dead, but not during life. A self-digestion may also be caused if the arteries of the stomach are ligatured. Claude Bernard and others suggested that the layer of mucus protected the cells of the stomach and of the intestine from the digestive enzymes; or that the epithelial layer had a protective effect. Pavy suggested that the alkali of the blood had a protective action. All these theories became untenable when Fermi showed that all kinds of living organisms, protozoans, worms, arthropods, are not digested in solutions of trypsin as long as they are alive, while they are promptly digested in the same solution when dead. This is in harmony with the fact that many parasites live in the intestine without being digested as long as they are alive. Fermi concluded that the living cell cannot be attacked by the digestive ferments, while with death a change occurs by which they can be attacked. But what is this change? Fermi seems to be inclined to think that the “living molecule” of protein is not hydrolysable (perhaps because the enzyme cannot attach itself to it?), while a change in the constitution or configuration of the proteins takes place after respiration has ceased. The fact that the living cell resists the digestive action of trypsin and pepsin has found two other modes of explanation, first, that the cells are surrounded by a membrane or envelope through which the enzyme cannot diffuse, and second, that the living cells possess antiferments. But the so-called antiferments are also said to exist after the death of the cell, whereas after death the cell is promptly digested. Frédéricq, as well as Klug, has shown that worms which are not attacked by trypsin are digested by this enzyme when they are cut into small pieces; although the pieces of course contain the antienzyme. The other suggestion that a membrane impermeable for trypsin protects the cells would explain why living protozoa are not digested by trypsin, but it leaves another fact unexplained, namely, the autodigestion of all the cells after death by enzymes contained in the cells themselves.

Fermi, C., Centralbl. f. Bacteriologie, Abt. 1, 1910, lvi., 55.

2. The disintegration of the body after death is not caused exclusively or even chiefly by the digestive enzymes of the intestinal tract or the micro-organisms entering the dead body from the outside, but by the enzymes contained in the cells themselves. This phenomenon of autolysis was first characterized by Hoppe-Seyler.

All organs suffering death within the organism, in the absence of oxygen, undergo softening and dissolution in a manner resembling that of putrefaction. In the course of that process, albuminous matter gives rise to leucin and tyrosin, fat to free acids and soaps. This maceration, identical with the pathological conception of softening, is accomplished without giving rise to ill odour and is a process similar to the one resulting from the action of water, acids, and digestive enzymes.

Levene, P. A., Autolysis. The Harvey Lectures, 1905-1906, p. 73, gives a full account of the work on this subject up to 1905.

Hoppe-Seyler, F., Tübinger med.-chem. Untersuchungen, 1871, P. 499.

In work of this kind, rigid asepsis is required to exclude the possibility of bacterial infection and this was first done by Salkowski, who showed that in aseptically kept tissues like liver and muscle the amount of substances that can be extracted with hot water increases considerably. By the work of others, especially Martin Jacoby and Levene, it was established that the power of self-digestion is shared by all organs. Analysis of the products of the autodigestion of tissues shows that, e. g., the amino acids, which constitute the proteins, are produced. Dakin, Jones, and Levene demonstrated the hydrolytic products of the nucleins, in the case of the self-digestion of tissues.

Levene, P. A., Am. Jour. Physiol., 1904, xii., 276.

Again the question arises: Why do the tissues not undergo autolysis during lifetime and what protects them, and the answer is that self-digestion is a consequence of the lack of oxidations. The presence of antiferments must continue after death and cannot be the cause which prevents the self-digestion during life, since nothing indicates the destruction of the hypothetical antidigestive enzymes through lack of oxygen. The recent work of Bradley and Morse and of Bradley has thrown some light on the problem. These authors found that proteins of the liver which are indigestible can be made digestible by the liver enzymes if an acid salt or a trace of acid is added to the mixture. A m/200 HCl solution gives marked acceleration of the autodigestion of the liver. This would explain why autodigestion takes place after oxidations cease. In many if not all the cells, acids are constantly formed during lifetime, e. g., lactic acid, which through oxidation are turned to CO₂, and this diffuses into the blood so that the H ion concentration in the cells does not rise materially. If, however, the oxidations cease, as is the case after death, the formation of lactic acid continues, but the acid is not oxidized to CO₂ and thus removed, and as a consequence the H ion concentration increases in the cells and the self-digestion of proteins, which the digestive enzymes contained in the cells themselves could not attack formerly, becomes possible. Acid increases the digestibility of a protein, probably by salt formation. Theoretically we should not be surprised that while in the liver an increase in the C{H} favours autolysis in other tissues the same result is produced by the reverse effect. We might say that the preservation of a certain C{H} probably at or near the point of neutrality during life prevents self-digestion, while the gross alteration of the C{H} in either direction after death (or after the cessation of oxidations in the tissues) induces autolysis. Bradley indeed suggests that many of the phenomena of autolysis during lifetime, such as atrophy, necrosis, involution, might be due to an increase in the C{H} in the tissues.

Bradley, H. C., and Morse, M., Jour. Biol. Chem., 1915, xxi., 209.

Bradley, H. C., ibid., 1915, xxii., 113.

These facts agree with the suggestion of Fermi that in the living cell the proteins cannot be attacked by the digestive enzymes but relieves us of the necessity of making the monstrous assumption of a “living molecule” of proteins as distinct from a “dead” molecule. The difference between life and death is not one between living and dead molecules, but more likely between the excess of synthetic over hydrolytic processes.

In the second chapter we mentioned the interesting idea of Armstrong that when a synthesis is brought about by a digestive enzyme (e. g., maltase) not the original substrate is formed (e. g., maltose) but an isomer, in this case isomaltose; and this isomer is not attacked by the enzyme maltase. We thus get a rational understanding of the statement which Claude Bernard used to make but which remained at his time mysterious: la vie, c’est la création. During life, when nutritive material is abundant, through the reversible action of certain enzymes, synthetic compounds are formed from the building stones furnished by the blood. These synthetic isomers cannot be hydrolyzed by the enzymes by which they are formed and hence on account of the isomeric structure are immune against destruction. It is not impossible that the increase of the concentration of acid in the cells after death transforms the isomers into that form in which they can be digested by the enzymes contained in the cell. Another possibility is that the increase in digestibility brought about by an increase in C_{H} in the cell is due to the hydrating effect of acids on proteins with a subsequent increase in digestibility. Whatever the answer may be, the work done since Claude Bernard has removed that cloud of obscurity which in his days surrounded the prevalence of synthetic action in the living and of disintegration in the dead tissues.

3. We have already referred to the connection between the lack of oxygen and the onset of autolysis and disintegration of tissues in the body. It is of interest that there are cells in which the disintegration under the influence of lack of oxygen is so rapid that it can be followed under the microscope. The writer has observed that certain cells undergo complete irreversible dissolution in a very short time under the influence of lack of oxygen, e. g., the first segmentation cells of the egg of a teleost fish Ctenolabrus.

Loeb, J., Arch. f. d. ges. Physiol., 1895, lxii., 249.

When these eggs are deprived of oxygen at the time they reach the eight- or sixteen-cell stage, it can be noticed that the membranes of the blastomeres are transformed into small droplets within half an hour or more, according to the temperature. These droplets begin to flow together, forming larger drops. [Figures 48 to 51 show the successive stages of this process.] When the eggs are exposed to the air in time, segmentation can begin again; but if a slightly longer time is allowed to elapse, the process becomes irreversible and life becomes extinct. Such clear structural changes cannot often be observed in the eggs of other animals under the same conditions. Are these changes of structure (apparently liquefaction of solid elements) responsible for death under such conditions? In order to obtain an answer to this question, the writer investigated the effect of the lack of oxygen upon the heart-beat of the embryo of the same fish Ctenolabrus. This egg is perfectly transparent and the heart-beat can easily be watched. When these eggs are put into an Engelmann gas chamber and a current of pure hydrogen is sent through, the heart may cease to beat in fifteen or twenty minutes; it stops beating suddenly, before the number of heart-beats has diminished noticeably, and ceases beating before all the free oxygen can have had time to diffuse from the egg. In one case the heart beat ninety times per minute before the hydrogen was sent through; four minutes after the current of hydrogen had passed through the gas chamber, the rate of the heart-beat was eighty-seven per minute, three minutes later it was seventy-seven, and then the beats stopped suddenly. It is hard to believe that this cessation could have been caused by lack of energy. Hydrolytic processes alone could furnish sufficient energy to maintain the heart-beat for some time, even if all the oxygen had been used up. The suddenness of the standstill at a time when the rate had hardly diminished seems to be more easily explained by a sudden collapse of the machine; it might be that liquefaction or some other change of structure occurs in the heart or its ganglion cells, comparable to that which we mentioned before. In another fish Fundulus, where the cleavage cells undergo no visible changes in the case of lack of oxygen, the heart of the embryo can continue to beat for about twelve hours in a current of hydrogen. In this case the rate of the heart-beat sinks during the first hour in the hydrogen current from about one hundred to twenty or ten per minute; then it continues to beat at this rate for ten hours or more. In this case one might believe that during the period of steady diminution of the tension of oxygen in the heart (during the first hour), the heart-beat sinks steadily while it keeps up at a low but steady rate as long as the energy for the beat is supplied solely by hydrolytic processes; but there is certainly no change in the physical structure of the cells noticeable in Fundulus, and consequently there is no sudden standstill of the heart.

Budgett has observed that in many infusorians visible changes of structure occur in the case of lack of oxygen; as a rule the membrane of the infusorian bursts or breaks at one point, whereby the liquid contents flow out. Hardesty and the writer found that Paramœcium becomes more strongly vacuolized when deprived of oxygen, and at last bursts. Amœbæ likewise become vacuolized and burst under these conditions. Budgett found that a number of poisons, such as potassium cyanide, morphine, quinine, antipyrine, nicotine, and atropine, produce structural changes of the same character as those described for lack of oxygen. As far as KCN is concerned, Schoenbein had already observed that it retards the oxidation in the tissues, and Claude Bernard and Geppert confirmed this observation. For the alkaloids, W. S. Young has shown that they are capable of retarding certain processes of autoxidation. This accounts for the fact that the above-mentioned poisons produce changes similar to those observed in the case of lack of oxygen.

Budgett, S. P., Am. Jour. Physiol., 1898, i., 210.

Loeb, J., The Dynamics of Living Matter, New York, 1906, pp. 19-21.

The phenomenon of rapid disintegration when deprived of oxygen (or in the presence of KCN) seems to be general as Child has shown in extensive experiments. Child has used it to show that younger animals disintegrate more rapidly than older or larger ones, and he uses this fact for a theory of senescence. He connects the more rapid disintegration of the young animal with a greater metabolism. Without wishing to doubt Child’s interesting observations the writer is not quite certain whether the more rapid disintegration of the younger forms is not a result of the fact that the walls of membranes in the young are softer than those of the older animals, and hence are more readily liquefied. Such a difference could be due to mere chemical constitution, e. g., the increase in Ca in the membrane with the increase in age. In old age in man the deposit of Ca in the blood-vessels is a frequent occurrence.

Child, C. M., Senescence and Rejuvenescence, Chicago, 1915.

It is a fact that in the early cells of Ctenolabrus the dissolution of the cell walls through lack of O precedes death, since when oxygen is admitted early enough the cells recover again. In infusorians the bursting of the animal due to lack of O occurs suddenly, while the animal is still moving, and this bursting is the cause of death, and not the reverse.

These facts may help us to understand the nature of death and dissolution of the body in higher animals. Death in these animals is due to cessation of oxidations, but the surprising fact is that if the oxidations have been interrupted but a few minutes life cannot be restored even by artificial respiration. This suggests that the respiratory ganglia in the medulla oblongata suffer an irreparable injury or an irreversible change (comparable to that just described in the cells of Ctenolabrus) even when deprived of oxygen for only a short time. As a consequence of the irreversible injury to the medulla the respirations cease permanently, the heart-beat must also cease, and gradually the different tissues must undergo the dissolution characteristic of death. While all the cells may be immortal they are only so in the presence of oxygen and the nutritive solution which the circulating blood furnishes. With the proper supply of oxygen cut off they can no longer live.

4. It is an unquestionable fact that each form has a quite definite duration of life. Unicellular organisms are immortal; but for the higher organisms with sexual reproduction the duration of life is almost as characteristic as any morphological peculiarity of a species. No species can exist unless the natural life of its individuals outlasts the period of sexual maturity; and unless the average duration of life is long enough to allow as many offspring to be brought into the world as will compensate for loss by death. The male bee dies before it is a year old, while the queen may live several years. In a certain species of butterflies, the Psychidæ, the parthenogenetic female lays its eggs while still in the cocoon and then dies without ever leaving the cocoon. The imago of the ephemera leaves the water in the evening, copulates, lets its eggs fall into the water, and is dead the next morning. The imperfect condition of their mandibles and alimentary canal makes them unfit for a long duration of life. The males of the rotifers which are devoid of organs of digestion live but a few days.

In the Zoölogical Station at Naples in 1906, an actinian, Actinia equina, was alive after having been in captivity fifteen years, and another one, Cerianthus, had been observed for twenty-four years. Korschelt kept earthworms for as long as ten years. The fresh-water mussel may reach the age of sixty years or more and crayfish may live for over twenty years. The differences in the duration of life of mammals are too well known to need discussion. If the cells and tissues are immortal, how does it happen that the duration of life is so characteristic for each species?

Metchnikoff has recently investigated the cause of “natural” death in the butterfly of the silkworm. The butterfly in this species lacks the organs necessary for taking up food, like the male rotifer or the ephemeridæ and hence is already, by this fact, condemned to a short life. Metchnikoff observed that these butterflies could live twenty-three days, but the average duration of life was 15.6 for the males and 16.6 days for the females; and that seventy-five per cent. of them contained no parasitic fauna or flora in their intestine. They lose considerably in weight during their lives, but the males still contain the fat body at the time of death. None of the changes accompanying “old age” in man are found in the tissues of these butterflies before death. Metchnikoff is inclined to believe that the animal is poisoned by some excretion retained in the body; namely, the urine, and that this poison also causes the symptoms of weakness which characterize the animal. He could prove the toxic character of their urine on other animals. This combined with starvation could sufficiently account for the short duration of life. The facts of the case show that it is due to an imperfection in the construction of the organism such as one would expect to find more or less in each animal if one discards the idea of purposefulness and divine wisdom in nature. Only a slight, perhaps an infinitesimal, fraction, of those species which are theoretically possible and which at one time or another arise can survive. Those which are durable show all transitions from the grossest disharmonies to an apparent lack of such shortcomings.

Metchnikoff, E., Ann. d. l’Inst. Pasteur, 1915, xxix., 477.

5. Minot had tried to prove that the death of metazoa is due to the greater differentiation and specialization of their tissues. Admitting the immortality of the unicellular organisms he argues that death is the price metazoa pay for the higher differentiation of their cells. This is of course purely metaphorical, but we may put it into a form in which it is capable of discussion in physicochemical terms, by assuming that death is a necessary stage in the development of a species. We are inclined, however, to follow Metchnikoff and suspect some poison accidentally or unavoidably formed in the body or some structural shortcoming as the cause of “natural” death.

An unusually favourable object for the study of natural death is the animal egg. The egg of the starfish Asterias forbesii when taken out of the body is usually immature, but in the spawning season it ripens in sea water. The writer observed that eggs which ripen disintegrate very rapidly when not fertilized. This disintegration may be due to a process of autolysis, which sets in only after the egg has extruded the two polar bodies. The writer found that by preventing the maturation of the egg either by withdrawing the oxygen or by replacing the alkaline sea water by a neutral solution or by exposing the eggs for some time to acidulated sea water, the disintegration could also be prevented.

Loeb, J., Biol. Bull., 1902, iii., 295.

Further experiments showed that even in the mature egg rapid disintegration could be prevented by lack of oxygen, and similar results were obtained by Mathews. When the egg is fertilized it does not disintegrate in the presence of oxygen but it gradually dies in the absence of oxygen. One is almost tempted to say that while the fertilized egg is a strict aërobe the mature unfertilized egg is an anaërobe. This latter statement, however, becomes doubtful since the presence of oxygen may help the disintegration only indirectly by allowing certain changes to go on in the egg. The important points for us are that duration of life in the mature unfertilized egg is comparatively short and that the entrance of a spermatozoön or the process of artificial parthenogenesis saves the life of the egg. Loeb and Lewis found that the life of the unfertilized sea-urchin egg (which is usually mature when removed from the ovaries) can also be prolonged when its oxidations are suppressed. The decay of the unfertilized egg seems to be due to the fact that those alterations in the cortical layer which underlie the membrane formation and which are responsible for the starting of development gradually take place. In such a condition the egg will die quickly unless deprived of oxygen. This view is supported by the observation of Wasteneys that unfertilized eggs of Arbacia show an increased rate of oxidations when allowed to remain for some time in sea water; we have seen in Chapter V that such an increase also accompanies artificial membrane formation.

6. If the limited duration of life of an organism is determined by one or more definite harmful chemical processes, we should expect to find a temperature coefficient for the duration of life or at least be able to show that if all other conditions are the same the duration of life is for a given organism a function of temperature. The writer investigated the duration of life of fertilized and unfertilized eggs of Strongylocentrotus purpuratus for the upper temperature limits.

Loeb, J., Arch. f. d. ges. Physiol., 1908, cxxiv., 411.

TABLE XX

-------------+----------------------------------------------- |Duration of life of the eggs of S. purpuratus -------------+-----------------------+----------------------- Temperature| Unfertilized | Fertilized -------------+-----------------------+----------------------- °C. | Minutes | Minutes | | 32 | { > 1-1/6 | 1-1/2 | { < 2 | | | 31 | | { > 2-1/4 | | { < 3 | | 30 | { > 3 | { > 4 | { < 5 | { < 5 | | 29 | | { > 6 | | { < 7 | | 28 | { > 8 | { > 11 | { < 10 | { < 13 | | 27 | about 18 | { > 20 | | { < 22 | | 26 | { > 35 | { > 35 | { < 40 | { < 40 | | 25 | | { > 76 | | { < 81 | | 24 | { > 168 | { > 192 | { < 200 | { < 209 | | | | Hours | | 22 | | 10-1/5 | | 21 | | 24 | | 20 | | 72 -------------+-----------------------+-----------------------

These observations show a very high temperature coefficient near the upper temperature limit, and this may account at least partly for the fact that in tropical seas the pelagic fauna is so much more limited than in polar seas. It is quite probable that the high temperature coefficients at the utmost limits are only an expression of the coagulation time of certain proteins.

K. Brandt (“Über den Nitratgehalt des Ozeanwassers and seine biologische Bedeutung,” Abh. d. kais. Leop. Carol. deutsch. Akad. d. Naturfoscher., 1915) accounts for this fact by the assumption that through the greater activity of the denitrifying bacteria in the tropical waters the amount of available nitrates is here comparatively smaller than in the polar oceans. The writer fully appreciates the importance of this fact but nevertheless is inclined also to see a limiting factor in the enormously rapid decline of the duration of life at the upper temperature limits.

P. and N. Rau state that in the cold certain butterflies live longer, and similar statements exist for the silkworm, but these statements are not based on exact experiments, which are difficult. Dr. Northrop and the writer have started experiments on the influence of temperature on the duration of life of the fly Drosophila. Newly hatched flies were kept first without food except water and air at 34°, 28°, 24°, 19°, 14°, and 10°, and second with cane sugar. The average duration of life was as follows:

With water days With cane sugar days 34° 2.1 6.2 28° 2.4 7.2 24° 2.4 9.4 19° 4.1 12.3 14° 8.3 10° 11.9

These experiments show that there is a definite temperature coefficient for the duration of life and that this coefficient is of the order of magnitude of that of a chemical reaction. We are continuing these experiments with animals in the presence of food. It should, however, be remembered that the fly carries with it a good deal of reserve material from the larval period. We have carried on simultaneously determinations of the temperature coefficients of the duration of the larval and pupa stage of these organisms at the same temperatures and found ratios similar to those given above for the duration of life with water only.

7. Metchnikoff has furnished the scientific facts for our understanding of senescence. He has demonstrated that the changes in tissue which give rise to phenomena of senility are due to the action of phagocytes. Thus the ganglion cells are altered (digested?) and destroyed by “neuronophags” and this is the main cause of mental senility. Definite phagocytic cells, the osteoclasts, slowly dissolve the bones (by the excretion of an acid?) and this leads to the known fragility of the bones in old age. The whiteness of the hair is due to the action of phagocytes; in the muscles in old age the contractile elements are destroyed by the sarcoplasm, and so on. It agrees with these facts that where organs are absorbed in the embryonic development of an animal, as e. g., the tail of the tadpole in metamorphosis, the phenomenon is due to a process of phagocytosis (and autolysis). We have mentioned the fact that in the larva of the Amblystoma the absorption of the gills and of the tail occurs simultaneously and that both must be caused by a constituent of the blood. Such a constituent may be responsible for phagocytosis and autolysis in the organs undergoing absorption. Metchnikoff calls attention to the fact that certain infectious diseases, e. g., syphilis, may bring about precocious senility; and he mentions also the senile appearance of young cretins which is due to the diseased thyroid. “It is no mere analogy to suppose that human senescence is the result of a slow but chronic poisoning of the organism.” He assumes that in man this poisoning is caused by the products of fermentation in the large intestine and that the micro-organisms responsible for these fermentations may therefore be regarded as the real cause of senility in man. Parrots which are long-lived birds have a limited flora of microbes in their intestine, while cows and horses which are short-lived in comparison with man possess an extraordinary richness of the intestinal flora. But, needless to say, it is not the quantity of microbes alone which is to be considered, the nature of the microbes is of much greater importance.

Metchnikoff, E., The Prolongation of Life. New York, 1907.

Certain plants like the Californian Sequoia gigantea may be considered as practically immortal since they live several thousands of years; other plants, the annuals, die after fructification. Metchnikoff quotes from a letter by de Vries that this author prolonged the life of Œnotheras by cutting the flowers before fertilization.

Under ordinary conditions the stem dies after producing from forty to fifty flowers, but if cutting be practised new flowers are produced until the winter cold intervenes. By cutting the stem sufficiently early the plants are induced to develop new buds at the base and these buds survive winter and resume growth in the following spring.

Metchnikoff suggests that it is a poison formed in the plant (in connection with fructification?) which kills the annuals, while it is not formed or is less harmful in the perennials. He compares the situation to the death of the lactic acid bacilli if the lactic acid is allowed to accumulate. This hypothesis is certainly worthy of consideration, and it is quite possible that in addition to structural shortcomings poisons formed by certain organs of the body as well as poisons formed by bacteria account for the phenomenon of death in metazoa.

INDEX

Abraxas, 203, 238, 241

Acquired characters, inheritance of, 337 ff.

Actinia equina, 361

Adaptation, 12, 318 ff.; to life in caves, 319 ff.; fresh and salt water, 327 ff.; poisons, 332 ff.; temperature, 334 ff.; caused by hormones, 342

Addison, W. H. F., 188

Agglutination, of corpuscles by sera, 67 ff.; of sperm, 78, 82 ff.

Allolobophora terrestris, 46

Alpheus, 176

Alytes obstetricans, 337, 338

Amanita phalloides, 63

Amblystoma, 157, 368

Amelung, 184

Amphipyra, 283

Analogies between living and dead matter, 14 ff.

Anaphylaxis reaction, 61 ff.

Ancel, 158, 225 ff.

Antagonistic salt action. See Balanced salt solutions.

Antennularia antennina, 194, 196

Apes, blood relationship to man, 54, 56 ff.

Apolant, 45

Arbacia, 75 ff., 96, 99, 101, 111, 114, 150, 190 ff., 293 ff., 298, 299, 364

Arenicola, 277

Armstrong, E. F., 26, 28, 354

Arrhenius, S., 33 ff., 88, 290, 296

Arrhenoidy, 218, 225

Artificial parthenogenesis, 95 ff.; in sea urchins, 95 ff.; new method of, 98, 99; by blood, 101 ff.; by sperm extract, 103; by acids, 105; by mechanical agitation, 107; in starfish, 110; rôle of hypertonic solution, 112, 115, 116; and oxidation, 116, 117, 118; and permeability, 119 ff.; in frogs, 124; and determination of sex, 125

Artificial production of life, 38-39

Assimilation of CO₂ without chlorophyll, 17 ff.

Asterias, 49, 81, 110, 363; ochracea, 73 ff.; capitata, 74

Asterina, 75, 81, 110

Astrospheres, 115 ff., 192

Auer, J., 315

Autolysis, 351 ff.

Avena, 263

B. coli communis, 36; typhosus, 36; fluorescens, 334

Bacteria, growth of, 15 ff., 29, 71 ff.; specificity in, 41 ff.

“Bacterio-purpurin,” 41

Balanced salt solutions, 307-317; theory of, 317; and adaptation, 331 ff.

Balanus, 259

Baltzer, F., 215 ff.

Bancroft, F. W., 70, 125, 127, 264, 269 ff.

Bang, 63

Bardeen, C. R., 174 ff.

Barnacle, larvæ of, 313 ff.

Bataillon, 124

Bateson, W., 230, 240 ff., 338, 348

Batrachia, 338

Baur, E., 48, 246

Bayliss, 63

Becquerel, P., 36 ff.

Beggiatoa, 19

Beijerinck, M., 20

Berkeley, Lord, 111

Bernard, Claude, 2 ff., 26, 159, 350, 354, 355, 358

Berthelot, 290

Bertrand, G., 248 ff.

Beutner, R., 140

Bichat, 2, 349

Bickford, E. E., 169

Blaauw, H. A., 263

Blackman, F. F., 302

Blastomeres, 141 ff.

Blind animals, 319 ff.

Blood, transfusion of, 53 ff.

Blood relationship, established by transfusion, 53, 54 ff.; precipitin reaction, 55 ff.; anaphylaxis reaction, 61 ff.; hemoglobin crystals, 64 ff.

Blood serum, precipitin reaction of, 54 ff.; effect of, on unfertilized eggs, 101 ff., 124

Blowfly, heliotropism of larvæ of, 265 ff.

Bohn, G., 253, 264, 269

Bombinator igneus, 46

Bonellia, 215

Bonnet, 154, 161

Bordet, 54 ff., 60

Bouin, 158, 225 ff.

Boveri, Th., 8, 126, 128 ff., 134, 138 ff., 150 ff., 186 ff., 209 ff., 246

Brachystola, 199

Bradley, H. C., 27, 64, 353, 354

Brandt, 366

Braus, H., 147

Bridges, C. B., 208, 229, 231 ff.

Brown, A. P., 64 ff.

Bruchmann, H., 93

Bryophyllum calycinum, 153, 160 ff., 177

Buchner, 24

Budgett, 358

Buller, 93

Bunsen-Roscoe, law of, 11, 256 ff., 261, 263, 264

Burrows, 31

Campanularia, 178, 181

Cannon, W. B., 285

Carcinus mænas, 217

Cardamine pratensis, 90

Carrel, 31

Cassia bicapsularis, 37

Castle, W. E., 89 ff., 335

Caullery, M., 158, 180, 217

Cave animals, 319 ff.

Cell division, 15, 29, 129 ff.; suppression of, 113 ff.

Cells, nutritive media of, 15 ff; immortality of, 30 ff.; migrating, 44; mesenchyme, 51 ff., 130 ff., 147, 155 ff.

Cerianthus membranaceus, 171 ff., 188, 361

Chætopterus, 78 ff.

Chamberlain, M. M., 293, 297

Chapman, H. G., 60

Chemotropism of spermatozoa, 92 ff.

Chevreul, 289

Child, C. M., 7, 170, 177, 358

Chlamydomonas, 277

Chodat, R., 248

Chologaster, 320

Christen, 288

Chromosomes, rôle of, in sex determination, 198 ff.; theory of Mendelian heredity, 233

Chun, 142

Ciona intestinalis, 89 ff., 212

Cladocera, 159

Clausen, H., 302

Clavellina, 181

Cohen, E., 292

Cohn, 41 ff.

Compton, 90

Conklin, E. G., 129, 134, 143, 145 ff.

Constancy of species, 40-43

Copernicus, 346

Corpus luteum, action of, 157-158

Correlation, 154, 167

Correns, C., 90 ff., 214

Cramer, 289

Crampton, H. E., 143, 225

Criodrilus lacuum, 219-220

Crossing over of chromosomes, 241 ff.

Crystals, differences between living organisms and, 14 ff.

Ctenolabrus, 355, 357, 359

Ctenophores, 142

Cuénot, L., 12, 324

Cullen, G. E., 24, 291

Cuma rathkii, 318

Cyanophyceæ, 287

Cytisus biflorus, 37

Cytoplasm of eggs as future embryo, 8, 9, 70, 126, 151 ff.

Dakin, 352

Dallinger, 334

Daphnia, 210, 262, 279, 280, 282, 306, 312

Darbishire, A. D., 347

Darwin, 90, 297, 346 ff.

Darwinian theory, 5 ff.

Davenport, C. B., 244, 335

Death, 349 ff.; natural, cause of, 364, 369

Decidua formation induced by corpus luteum, 157-158

Delage, Y., 107, 110, 111, 123, 126, 186

de la Rive, 24

de Meyer, J., 127

Dendrostoma, 101

Dentalium, 144

Design, 4, 5

Determination of sex, in bees, 208 ff.; in phylloxerans, 210; in Bonellia, 215

Development of egg, 127 ff.

de Vries, H., 6, 42, 154, 161, 347, 369

Dewitz, 93

Dieudonné, C., 334, 337

“Directive force,” 2

Disharmonies, 7

Divisibility of living matter, limits of, 148-151

Dominance, 230

Doncaster, L., 203

Dorfmeister, 303

Driesch, H., 4 ff., 128, 133, 136, 138 ff., 147, 150, 169 ff., 180 ff., 184 ff.

Drosophila ampelophila, 204 ff., 237, 243, 322, 347, 366

Duclaux, E., 288, 289

v. Dungern, 80

Duration of life, 360 ff.

Durham, 249

Dutrochet, 154

Dzierzon, 208

Ectoderm formation, 130 ff.

Egg, as the future embryo, 8, 9, 70, 126, 151; artificial parthenogenesis of, 95 ff.; organisms from, 128 ff.; determining unity of organism, 151-152; chromosomes in, 198 ff.

Egg structure, 129 ff.; influence of centrifugal force on, 135; and regulation, 139, 140, 141; and fluidity of protoplasm, 141

Ehrlich, 45, 322, 332 ff., 341; side-chain theory of, 88, 188

Eigenmann, 320, 323 ff.

Electromotive forces, origin in living organs, 140

Engelmann, 357

Engler, 24

Entelechy, 4, 170, 182

Environment, influence of, 286 ff.; temperature, 288 ff., 344 ff.; salinity, 306; adaptation to, 319

Enzyme action, 23 ff., 297, 302

Ernst, A., 21

Eternity of life, 34 ff., 360

Eudendrium, 260, 261, 269, 277, 278, 326

Eudorina, 277

Euglena, 264, 269, 272, 277

Euler, H., 21

Evolution, 346 ff.; and mutation, 348

Ewald, W. F., 261 ff., 269, 280, 301

Farmer, J. B., 347

Fermi, 350, 354

Fertilization, heterogeneous, 48 ff., 51, 73 ff.; specificity in, 71 ff.; and oxidation, 117 ff.; and permeability, 119 ff.

“Fertilizin,” 84, 87 ff., 93

Fischel, 187

Fischer, 303 ff.

Fish, 55

Fitness of environment, 317

Fitzgerald, J. G., 63

Flow of substances and regeneration in Bryophyllum, 161 ff.

Fluctuating variations, 6, 297 ff., 346 ff.

Folin, 22

Food, influence on polymorphism in wasps, 222 ff.

Food castration, 224; influence on sexual cycle in rotifers, 224; on metamorphosis in tadpoles, 155

Ford, 63

Forssmann, 63

Frédéricq, 351

Free-martin, cause of sterility, 218-219

Friedenthal, H., 53 ff., 60

Frisch, K., 278, 279

Fröschel, P., 263

Fuchs, H. M., 90

Fucus, 123

Fundulus heteroclitus, 51, 116, 147, 300, 301, 302, 307 ff., 321 ff., 328 ff., 335, 337, 357 ff.

Galileo, 346

Galvanotropism, 11, 270 ff., 319

Gay, F. P., 62 ff.

Generation, spontaneous, 14 ff., 34

Genes, 4 ff., 152, 319

Genus and species, chemical basis of, 40 ff.

Geppert, 358

Germination in seeds, 35 ff.

Giard, 180, 216 ff.

Godlewski, E., 48, 75, 78, 120, 126, 169

Godlewski, E., Sr., 18

Goebel, K., 154, 161

Goldfarb, A. J., 326

Goldschmidt, R., 220 ff.

Goodale, H. D., 218

Gortner, R., 249

Graber, V., 256, 276

Grafting, heteroplastic, in animals, 46; in plants, 47

Gravitation, influence on organ formation in Antennularia, 194 ff.; on the egg of the frog, 141

Gray, J., 122

Gregory, 243

Groom, T. T., 280

Growth, termination of, 184; influence of cell size, 187

Gudernatsch, J. F., 155, 255, 342

Guyer, 124

Gynandromorphism, 209

Haeckel, 346

Half-embryos and whole embryos, 141, 142

Hammond, J. H., Jr., 269

Harden, 16

Hardesty, 358

Harmonious character of organism, 5, 6, 318 ff., 341 ff.

Harrison, 31

Hartley, 111

Healing of wound, 187

Hektoen, 66

Heliotropism, 11 ff., 257 ff., 318; heredity of, 250 ff.; change of, 279, 280 ff.; and adaptation, 318

Helmholtz, 34

Hemoglobins, crystallographic measurements of, 64 ff.

Henderson, L., 317

Henking, 198 ff.

Herbst, C., 97, 147, 193, 306, 310

Heredity, of genus and species, 40 ff., 70, 151, 152; Mendelian, 70, 151 ff., 229 ff., 348; of sex, 198; sex-linked, 203 ff., 238 ff.; and evolution, 348

Herlant, M., 78 ff., 115 ff.

Hermaphroditism, 89 ff., 212 ff., 216, 219 ff. See also Inhibition and Regeneration.

Hertwig, O., 97, 123, 292

Hertwig, R., 95, 97

Hess, C., 278

Heterogeneous hybrids, purely maternal, 49, 50

Heterogeneous transplantation, Murphy’s experiments on, 44 ff.; limitation of, 46

Heteromorphosis, 155, 193-196

Hill, C., 25

Hippiscus, 199

Holmes, S. J., 269

Hoppe-Seyler, 351

Hormones, 145, 155, 181, 219; and Mendelian heredity, 245 ff., 348; and adaptation, 342. See also Organ-forming substances.

Huxley, 346

Hybridization, heterogeneous, in sea urchins, 48 ff., 73 ff.; in fishes, 51; in plants (Mendel’s), 230 ff.

Hydrolytic enzymes, action of, 24; reversible action of, 24 ff.

Hypertonic solution, 99, 111 ff.

Imitation of cell structures by colloids, 39

Immortality, of cancer cells, 30; of somatic cells, 30 ff.; of life in general, 34 ff.

Inheritance, of colour-blindness, 203, 204, 205; of eye pigment in Drosophila, 204 ff.; of pigments, 248 ff.; of acquired characters, 337 ff.

Inhibition of regeneration in Bryophyllum, 162 ff.

Inhibition of sexual characters of opposite sex, in pheasants, 218; lack of in hermaphrodites, 219; in Bonellia, 226

Instincts, 10 ff., 253 ff.; sexual, 198 ff.

Intersexualism, 221

Intestine, formation of, 130 ff.

Isoagglutinins, 66 ff., 92

Isolation of blastomeres, 136 ff.

Jacoby, 352

Janda, V., 219 ff.

Jansky, 67

Janssens, 242

Jennings, H. S., 264 ff.

Jensen, 45

Joest, 46

Johannsen, W., 42, 333

Jones, 352

Jost, 90

Kammerer, P., 325, 337 ff.

Kanitz, A., 290, 292, 296

Kastle, J. H., 26 ff.

Kellogg, V. L., 279

Kelvin, 34

King, W. O. R., 50, 247

Klug, 351

v. Knaffl, E., 106

Knowlton, E. P., 292

Kofoid, C. A., 143

v. Körösy, 300

Korschelt, 361

Krakatau, 21

Kraus, 54 ff.

Krogh, 292

Kryž, F., 335

Kupelwieser, H., 75

Lack of oxygen, influence on disintegration of tissue, 355 ff.

Ladoff, S., 224

Lamarck, 6

Laminaria, 165

Landois, L., 53

Landsteiner, 66

Lanice, 143 ff.

Lankester, E. R., 41

Leathes, J. B., 63

Leucæna leucocephala, 37

Levene, 351, 352

Lewis, 183, 344, 364

Light, influence on organ formation, in cave animals, 319 ff.; in Proteus, 325; in Eudendrium, 326. See also Heliotropism.

Lillie, F. R., 80, 82 ff., 87 ff., 93, 134, 191, 218, 292

Lillie, R. S., 101, 107, 110, 120 ff.

Lipase, synthetic action of, 26

Living and dead matter, specific differences between, 14 ff.

Lloyd, D. J., 111

Localization of Mendelian characters in individual chromosomes, 243, 244

Loeb, Leo, 30 ff., 45, 157, 170, 187 ff., 342

Loevenhart, A. S., 26 ff.

Lumbricus rubellus, 46

Lychnis dioica, 217

Lycopodium, 93

Lygæus, 201

Lymantria dispar, 220

Lymnæus, 142

Lymphocytes, rôle of, 45 ff.

Lyon, E. P., 134 ff.

Macfadyen, A., 36

Maeterlinck, 255

Magnus, W., 60

Maltase, synthetic action of, 25

Marchal, P., 222 ff., 254

Margelis, 192

Mass of chromatin and of cytoplasm, 186

Mast, 269, 277

Mathews, A. P., 107, 363

Matthaei, G. L. C., 302

Maxwell, S. S., 270, 274, 277

McClendon, J. F., 122, 322

McClung, C. E., 68, 198 ff., 237

Megusar, 340

Meignon, 217

Meisenheimer, 225

Meltzer, S.J., 315

Membrane formation, 86 ff.; artificial, 98 ff.

Mendel, G., 23, 229 ff.

Mendelian characters, and evolution, 70, 348; and internal secretions, 243, 348; and enzymes, 247, 248, 249

Mendelian, factors of heredity, 4 ff., 68, 151 ff.; mutation, 66; dominant, 90; segregation, 229 ff. See also Non-Mendelian inheritance.

Mendelian heredity, mechanism of, 229 ff.; and chromosomes, 233 ff.; and hormones, 245 ff., 348; and enzymes, 247 ff.

Menidia, 51, 321, 323

Merogony, 120, 126, 186

Merrifield, 303

Mesenchyme formation, 130 ff.

Metamorphosis of tadpoles induced by thyroid, 155, 156

Metchnikoff, 361 ff., 367 ff.

Michaelis, L., 62, 317

Micrococcus prodigiosus, 334

Micromeres, 132 ff.

Minot, 362

Moenkhaus, W. J., 51, 344

Molisch, 20

Montgomery, 199, 234

Moore, A. R., 50, 247 ff., 280

Morgan, T. H., 46, 68, 89 ff., 95, 116, 126, 134, 141 ff., 173, 175, 184, 204 ff., 229 ff., 241 ff., 244, 347

Morse, M., 156, 353

Morton, J. J., 44

Moss, W. L., 67

Muller, H. J., 229, 231 ff.

Murphy, J. B., 44 ff.

Mutation, 6, 42, 243; and evolution, 347, 348

Myers, 55

Nathanson, 19

Natural death, 361 ff.

Neilson, 110

Newman, 344

Newton’s Law, 253

Nitrifying bacteria, 16 ff.

Non-Mendelian inheritance, genus and species characters, 70, 151, 251; rate of segmentation, 246; first development, 247

Northrop, 366

Nostocaceæ, 21

Nussbaum, M., 149

Nuttall, G. H. F., 56 ff.

Ocneria dispar, 225

Œnotherus, 369

Onslow, H., 249

Organ-forming substances or hormones in regeneration, 154 ff.; causing metamorphosis in tadpoles, 155-157; decidua formation, 158; development of milk glands, 158; Sachs’s theory of, 159

Organisms from eggs, 128 ff.

Origin of life, 14 ff., 33 ff.

Osborne, 23

Osterhout, W. J. V., 312

Ostwald, Wo., 29, 305, 312

Oudemans, 225

Overton, 123

Palæmon, 193

Palæmonetas, 193; geotropism of, 270

Palinurus, 193

Pandorina, 277

Parker, G. H., 264, 269

Parthenogenesis, artificial, 95 ff.; “spontaneous,” 107

Pasteur, 14 ff., 24, 33, 38

Patten, B., 264 ff

Pauli, W., 289

Pavy, 350

Payne, F., 322

Pearl, R., 203, 244

Penicillium, 289

Pennaria, 192

Pepsin, synthetic action of, 28, 62, 63

Pfeffer, 92 ff.

Phagocytosis, 367

Planaria, 173 ff., 177

Planorbis, 142

Plants, heteroplastic grafting in, 47 ff.; regeneration in, 160 ff.

Polygordius, 280

Polymorphism, 222

Porthesia, 256, 280 ff.

Preadaptation, 12, 324

Precipitin reaction, 54 ff.

Preformation of organism in egg, 128 ff., 142-145

Presence and absence theory, 230 ff.

Primula, 243

Proteins, specific reactions of, 54 ff.; and species specificity, 68; and evolution, 70, 348

Protenor, 200 ff., 208

Proteus, 325 ff.

Przibram, H., 176

Pure lines, 333, 334

Pycnopodia spuria, 74

Pyrrhocoris, 198

Radiation pressure, rôle in transmission of spores through interstellar space, 34 ff.

Rana, esculenta, 46; palustris, 46; virescens, 46

Rate of segmentation, a non-Mendelian hereditary character, 246

Rau, 366

Reaction, tropistic, 11 ff., 92 ff., 147, 178, 187, 255 ff.; precipitin, 54 ff.; anaphylaxis, 61 ff.

Regeneration, 9 ff., 153 ff.; in plants, 160 ff.; in Bryophyllum, 161-167; in animals, 167 ff.; in Tubularia, 167-170; in Cerianthus, 171 ff.; in Planarians, 173-176; in Alpheus, 176; and autolysis, 178-181; of lens, 182, 183; external influences on, 192 ff.; of gonads in hermaphrodites, 219

Regulation, 139, 140, 141; in regeneration, see Regeneration.

Reichert, E. T., 64 ff.

Reseda, 90

Resistance of spores, 36; seeds, 36 ff.

Reversibility of development, in Campanularia, 178 ff.; in Ascidians, 180; in egg, 189 ff.; in Antennularia, 194

Rhabdonema nigrovenosum, 213

Richet, C., 61

Richter, 34

Ringer solution, 99

Robertson, T. B., 28 ff., 62 ff., 104, 311

Roentgen rays, 45

Roscoe, see Bunsen

Rotifers, determination of sexual cycle by food, 224

Roux, W., 141 ff.

Saccharomyces, 36; cerevisiæ, 60

Sacculina, 216 ff.

Sachs, 88

v. Sachs, J., 145, 154 ff., 159, 161, 184

Salamandra maculosa, 339

Salkowski, 352

Salts required for life, 306 ff.

Sansum, W. D., 64

Schizophyceæ, 21

Schleip, W., 213

Schoenbein, 358

Schottelius, 334, 337

Schroeder, 14, 33

Schultze, O., 141

Schütze, 55

Schwann, 33

Schwarzschild, 34

Secretions, internal, 145, 155, 157

Self-digestion, 350 ff.

Self-sterility, 89 ff.

Senescence, 367

Sequoia, 31, 368

Setchell, W. A., 165, 287

Sex, of parthenogenetic frogs, 125; of twins, 211

Sex chromosome, 199 ff.

Sex determination, cytological basis of, 198 ff.; physiological basis of, 214 ff.

Sexual characters, 198 ff.

Shibata, 93

Shull, A. F., 214, 224

Sicyonia, 193

Side-chain theory, 88, 188

Smith, Geoffrey, 159, 217

Smith, Graham, 58

Spain, K. C., 188

Spallanzani, 33

Species, chemical basis of, 40 ff.; specificity of, 41 ff.; incompatibility of, not closely related, 44 ff.

Species specificity, determined by proteins, 63, 68, 348; apparently not by nucleins, 69

Specificity, of grafted tissues, 47; of spermatozoa, 48; of blood sera, 53 ff.; in fertilization, 71 ff.; of activation of sperm by eggs, 80 ff.

Spelerpes, 320

Spermatozoa, fertilization of eggs by, 72 ff.; activation by eggs of, 80 ff.; agglutination of, 82 ff.; cluster formation of, 83; chemotropism of, 92 ff.; cultivating of, 126 ff.; chromosomes of, 198 ff.

Spirographis, 260

Spondylomorum, 277

Spontaneous generation, 33, 38

Spooner, G. B., 134

Standfuss, 303

Staphylococcus pyogenes aureus, 36

Steffenhagen, K., 55

Steinach, E., 225 ff., 254, 343

Stereotropism, 178, 187, 283

Stevens, Miss, 68, 199

Stimulus, 196

Stockard, 322, 340

Strassburger, 260

Streaming as means of egg differentiation, 145, 146

Strongylocentrotus franciscanus, 50, 52, 75, 81 ff., 103, 247

Strongylocentrotus lividus, 129

Strongylocentrotus purpuratus, 52, 73 ff., 81 ff., 94, 98 ff., 103, 108, 109, 111 ff., 137, 191, 246 ff., 293 ff., 364; larvæ of, 49 ff.

Sturtevant, A. H., 229 ff.

Styela, 146

Sulphur bacteria, 19 ff.

Supergenes, 5, 9, 136, 319

Sutton, W. S., 68, 233 ff.

Synthesis of living matter, by micro-organisms, 15 ff.; by enzymes, 24 ff.

Synthetic action of enzymes, 23 ff., 38

Tænia, 212

Talbot, 262

Tammann, 291

Tanaka, 243

Taylor, A. E., 27, 69 ff.

Tchistowitch, 54 ff.

Teleost fish, crosses of, 6 ff., 345

Temperature, effect on heliotropism, 280; upper limit for organisms, 287 ff.; effect on life, 288 ff.; on butterflies, 303 ff.; adaptation to, 334 ff.

Temperature coefficient, 290 ff., 305; for enzyme, 291; for development, 292 ff.; for oxidations, 295; and fluctuating variation, 296 ff.; for heart-beat, 300 ff.; for duration of life, 366

Thatcher, Miss, 181

Thyroid inducing metamorphosis in tadpoles, 155, 156

Tichomiroff, 95

Tissue culture of spermatozoa, 127

Tissues, transplantation of, 30 ff., 44 ff.; cultivation of, 31 ff.; specificity of, 44 ff.

Torrey, H. B., 264, 269

Tower, 348

Transfusion of blood, 53

Transplantation, of tissues, 30 ff., 44 ff.; of cancers, 45; of anlagen, 148; of eye of salamander, 157; of testes, 226; of ovaries, 227

Traube, 28

Treub, 21

Trial and error, 268, 270

Trifolium arvense, 37

Tropisms, 11 ff., 92 ff., 147, 178, 187, 253 ff.; and instincts, 253; theory of, 257 ff.

Tropisms, in embryonic development, 147; of cave animals, 324

Trypanosomes, 332 ff.

Trypsin, synthetic action of, 27

Tuber brumale, 60

Tubularia crocea, 171

Tubularia mesembryanthemum, 167, 169, 192

Twins, origin of, 136 ff.; sex of, 211

Tyndall, 33

Typhlogobius, 320

Typhlomolge, 320

Typhlotriton, 320, 323

Tyrosinase, 249, 250

Tyrosine, 249, 250

v. Uexküll, J., 4 ff., 128, 139

Uhlenhuth, E., 157, 183, 187

Uhlenhuth, P., 55, 58, 66, 322

Underhill, F. P., 23

Vanessa, prorsa, 303; levana, 303

Vaney, 217

Van Slyke, D. D., 22, 24, 291

van’t Hoff, 24 ff., 290, 292, 296

Variation, 6, 297 ff., 346-348

Vitzou, 159

Volvox, 280

Walcott, 42, 61

Warburg, O., 117 ff.

Warming, 41

Wasps, polymorphism in, 222-224; sex determination, 255 ff.

Wassermann, 55

Wasteneys, H., 29, 82, 87, 112, 113, 117, 191, 277, 293, 295, 335, 364

Weiggert, 188

Weismann, 7, 30, 303

Wells, H. G., 62, 69

Welsh, D. A., 60

Werner, F., 340

Wheeler, W. M., 43

White, J., 36

Whitney, D. D., 224

Wilson, E. B., 68, 143, 199 ff.

Winkler, 47

Winogradsky, S., 16 ff., 42

Wolf, G., 182, 187

Yeast cells, cultivation of, 15 ff.

Young, 16, 358

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The subject is presented in untechnical language and without the use of mathematics. Professor Poor shows by what steps the precise knowledge of to-day has been reached and explains the marvellous results of modern methods and modern observations.

=19.=--=Heredity.= By J. ARTHUR THOMSON, M.A., Professor of Natural History in the University of Aberdeen; Author of “The Science of Life,” etc. 8^o. Illustrated.

The aim of this work is to expound, in a simple manner, the facts of heredity and inheritance as at present known, the general conclusions which have been securely established, and the more important theories which have been formulated.

=20.=--=Climate--Considered Especially in Relation to Man.= By ROBERT DECOURCY WARD, Assistant Professor of Climatology in Harvard University. 8^o. Illustrated.

This volume is intended for persons who have not had special training in the technicalities of climatology. Climate covers a wholly different field from that included in the meteorological text-books. It handles broad questions of climate in a way which has not been attempted in a single volume. The needs of the teacher and student have been kept constantly in mind.

=21.=--=Age, Growth, and Death.= By CHARLES S. MINOT, James Stillman Professor of Comparative Anatomy in Harvard University, President of the Boston Society of Natural History, and Author of “Human Embryology,” “A Laboratory Text-book of Embryology,” etc. 8^o. Illustrated.

This volume deals with some of the fundamental problems of biology, and presents a series of views (the results of nearly thirty years of study), which the author has correlated for the first time in systematic form. #/

=22.=--=The Interpretation of Nature.= By C. LLOYD MORGAN, LL.D., F.R.S. Crown 8vo.

Dr. Morgan seeks to prove that a belief in purpose as the causal reality of which nature is an expression is not inconsistent with a full and whole-hearted acceptance of the explanations of naturalism.

=23.=--=Mosquito Life.= The Habits and Life Cycles of the Known Mosquitoes of the United States; Methods for their Control; and Keys for Easy Identification of the Species in their Various Stages. An account based on the investigation of the late James William Dupree, Surgeon-General of Louisiana, and upon the original observations by the Writer. By EVELYN GROESBEECK MITCHELL, A.B., M.S. With 64 Illustrations. 8^o.

This volume has been designed to meet the demand of the constantly increasing number of students for a work presenting in compact form the essential facts so far made known by scientific investigation in regard to the different phases of this, as is now conceded, important and highly interesting subject. While aiming to keep within reasonable bounds, that it may be used for work in the field and in the laboratory, no portion of the work has been slighted, or fundamental information omitted, in the endeavor to carry this plan into effect.

=24.=--=Thinking, Feeling, Doing.= An Introduction to Mental Science. By E. W. SCRIPTURE, Ph.D., M.D., Assistant Neurologist Columbia University, formerly Director of the Psychological Laboratory at Yale University. 189 Illustrations. 2d Edition, Revised and Enlarged. 8^o.

“The chapters on Time and Action, Reaction Time, Thinking Time, Rhythmic Action, and Power and Will are most interesting. This book should be carefully read by every one who desires to be familiar with the advances made in the study of the mind, which advances, in the last twenty-five years, have been quite as striking and epoch-making as the strides made in the more material lines of knowledge.”--Jour. Amer. Med. Ass’n., Feb. 22, 1908.

=25.=--=The World’s Gold.= By L. DE LAUNAY, Professor at the École Supérieure des Mines. Translated by Orlando Cyprian Williams. With an Introduction by Charles A. Conant, author of “History of Modern Banks of Issue,” etc. 8^o.

M. de Launay is a professor of considerable repute not only in France, but among scientists throughout the world. In this work he traces the various uses and phases of gold; first its geology; secondly, its extraction; thirdly, its economic value.

=26.=--=The Interpretation of Radium.= By FREDERICK SODDY, Lecturer in Physical Chemistry in the University of Glasgow. Third Edition, rewritten, with data brought down to 1912. 8^o With 33 Diagrams and Illustrations.

As the application of the present-day interpretation of Radium (that it is an element undergoing spontaneous disintegration) is not confined to the physical sciences, but has a wide and general bearing upon our whole outlook on Nature, Mr. Soddy has presented the subject in non-technical language, so that the ideas involved are within reach of the lay reader. No effort has been spared to get to the root of the matter and to secure accuracy, so that the book should prove serviceable to other fields of science and investigation, as well as to the general public.

=27.=--=The Social Evil.= With Special Reference to Conditions Existing in the City of New York. A Report Prepared in 1902 under the Direction of the Committee of Fifteen. Second Edition, Revised, with New Material Covering the Years 1902-1911. Edited by EDWIN R. A. SELIGMAN, LL.D., McVickar Professor of Political Economy in Columbia University. 8vo.

A study that is far from being of merely local interest and application. The problem is considered in all its aspects and, for this purpose, reference has been made to conditions prevailing in other communities and to the different attempts foreign cities have made to regulate vice.

=28.=--=Microbes and Toxins.= By ETIENNE BURNET, of the Pasteur Institute, Paris. With an Introduction by Élie Metchnikoff, Sub-Director of the Pasteur Institute, Paris. With about 71 Illustrations.

A well-known English authority said in recommending the volume: “Incomparably the best book there is on this tremendously important subject. In fact, I am assured that nothing exists which gives anything like so full a study of microbiology.” In the volume are considered the general functions of microbes, the microbes of the human system, the form and structure of microbes, the physiology of microbes, the pathogenic protozoa, toxins, tuberculin and mallein, immunity, applications of bacteriology, vaccines and serums, chemical remedies, etc. #/

=29.=--=Problems of Life and Reproduction.= By MARCUS HARTOG, D. Sc., Professor of Zoology in University College, Cork. 8vo.

The author uses all the legitimate arms of scientific controversy in assailing certain views that have been widely pressed on the general public with an assurance that must have given many the impression that they were protected by the universal consensus of biologists. Among the subjects considered are: “The Cellular Pedigree and the Problem of Heredity”; “The Relation of Brood-Formation to Ordinary Cell-Division”; “The New Force, Mitokinetism”; “Nuclear Reduction and the Function of Chroism”; “Fertilization”; “The Transmission of Acquired Characters”; “Mechanism and Life”; “The Biological Writings of Samuel Butler”; “Interpolation in Memory”; “The Teaching of Nature Study.”

=30.=--=Problems of the Sexes.= By JEAN FINOT, Author of “The Science of Happiness,” etc. Translated under authority by Mary J. Safford. 8vo.

A masterly presentation of the attitude of the ages toward women and an eloquent plea for her further enfranchisement from imposed and unnatural limitations. The range of scholarship that has been enlisted in the writing may well excite one’s wonder, but the tone of the book is popular and its appeal is not to any small section of the reading public but to all the classes and degrees of an age that, from present indications, will go down in history as the century of Woman.

=31.=--=The Positive Evolution of Religion.= Its Moral and Social Reaction. By FREDERIC HARRISON. 8vo.

The author has undertaken to estimate the moral and social reaction of various forms of Religion--beginning with Nature Worship, Polytheism, Catholicism, Protestantism, and Deism. The volume may be looked upon as the final word, the summary of the celebrated author’s philosophy--a systematic study of the entire religious problem.

=32.=--=The Science of Happiness.= By JEAN FINOT, Author of “Problems of the Sexes,” etc. Translated from the French by Mary J. Safford. 8^o.

In this work, which was crowned by the Academy, the author considers a subject, the solution of which offers more enticement to the well-wisher of the race than the gold of the Incas did to the treasure-seekers of Spain, who themselves doubtless looked upon the coveted yellow metal, however mistakenly, as a key to the happiness which all are trying to find. “Amid the noisy tumult of life, amid the dissonance that divides man from man,” remarks M. Finot, “the Science of Happiness tries to discover the divine link which binds humanity to happiness through the soul and through the union of souls.” The author considers the nature of happiness and the means of its attainment, as well as many allied questions.

=33.=--=Genetic Theory of Reality.= Being the Outcome of Genetic Logic as Issuing in the Æsthetic Theory of Reality Called Pancalism. By JAMES MARK BALDWIN, Ph.D., D.Sc., LL.D., Foreign Correspondent of the Institute of France, Author of “History of Psychology,” etc.

The author here states the general results of the extended studies in genetic and social science and anthropology made by him and others, and gives a critical account of the history of the interpretation of nature and man, both racial and philosophical.

The book offers an Introduction to Philosophy from a new point of view. It contains, also, a valuable glossary of the terms employed in these and similar discussions.

=34.=--=Mosquito Control in Panama.= The Eradication of Malaria and Yellow Fever in Cuba and Panama. By J. A. LE PRINCE, C.E., A. M., Chief Sanitary Inspector, Isthmian Canal Commission, 1904-1914, and A. J. ORENSTEIN, M.D., Assistant Chief Sanitary Inspector, Isthmian Canal Commission. With an introduction by L. O. HOWARD, Ph.D., Entomologist and Chief, Bureau of Entomology, United States Department of Agriculture. 8^o. 95 illustrations.

Mr. Le Prince’s books will be not only of great practical importance as a guide to future work of the same character, especially in the Tropics, but also of permanent historic value.

=35.=--=The Organism as a Whole.= From a Physico-Chemical Viewpoint. By JACQUES LOEB, Author of “Comparative Physiology of the Brain.” 8^o.

The author accounts for the harmonious character of the organism on a purely physico-chemical basis, without the assumption of design on the one hand, and without the formulation of too definite a theory of evolution on the other. The book contains, in addition to the text, all the necessary illustrations.

* * * * * *

Transcriber's note:

Footnotes have been repositioned to below the paragraph of reference or below the relevant block quote.

A small number of spelling anomalies were noted and these have mostly been corrected, but a few that possibly represent authentic contemporary alternatives have been left unchanged – see below.

Corrections:

spermatozoon-->spermatozoön i.e.-->i. e. e.g.-->e. g. nermaphrodite-->hermaphrodite suceeded-->succeeded ôf-->of tryosinase-->tyrosinase in-as-much-->inasmuch ultra-violet-->ultraviolet view-point-->viewpoint Fredericq-->Frédéricq Korösy-->Körösy Sitzngsber-->Sitzungsber negaceros-->megaceros

Variants:

clew/clue Entswcklngsmech/Entwcklngsmech/Entwicklngsmech peroxidase/peroxydase (latter spelling in quoted text.) 20°C/20° C (spaced and unspaced temperature specifications) 8vo/8^o