UNIVERSITY 
 CAUFOIW. 
 
 SAN DIEGO
 
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 LIFE AND DEATH 
 
 BV 
 A. jDASTRE, 
 
 PROFESSOR OF FHTSIOLOGT AT THB SOKBONXR 
 
 TRANSLATED BY 
 
 W. J. GREENSTREET, M.A., F.R.A.S. 
 
 THE WALTER SCOTT PUBLISHING CO., LTD., 
 
 PATERNOSTER SQUARE, LONDON, E.C 
 
 CHARLES SCRIBNER'S SONS, 
 
 153-157 FIFTH AVENUE, NEW YORK. 
 
 1911
 
 P|REFACE. 
 
 THE educated and inquiring public of the present 
 day addresses to the experts who have specialized 
 in every imaginable subject the question that was 
 asked in olden times of Euclid by King Ptolemy 
 Philadelphus, Protector of Letters. Recoiling in 
 dismay from the difficulties presented by the study 
 of mathematics and annoyed at his slow progress, he 
 inquired of the celebrated geometer if there was 
 not some royal road, could he not learn geometry 
 more easily than by studying the Elements. The 
 learned Greek replied, "There is no royal road. 3 
 These royal roads making every branch of science 
 accessible to the cultivated mind did not exist in 
 the days of Ptolemy and Euclid. But they do 
 exist to-day. These roads form what we call 
 Scientific Philosophy. 
 
 Scientific philosophy opens a path through the 
 hitherto inextricable medley of natural phenomena. 
 It throws light on facts, it lays bare principles, it 
 replaces contingent details by essential facts. And 
 thus it makes science accessible and communicable. 
 Intellectually it performs a very lofty function. 
 
 There is virtually a philosophy of every science, 
 v
 
 CONTENTS. 
 
 BOOK I. 
 
 THE FRONTIERS OF SCIENCE. GENERAL THEORIES OF 
 LIFE AND DEATH. THEIR SUCCESSIVE TRANS- 
 FORMATIONS, 
 
 CHAP. fAGE 
 
 I. EARLY THEORIES i 
 
 II. ANIMISM- 5 
 
 III. VITALISM 15 
 
 IV. THE MONISTIC THEORY 34 
 
 V. THE EMANCIPATION OF SCIENTIFIC RESEARCH FROM 
 
 THE YOKE OF PHILOSOPHICAL DOCTRINE . . 42 
 
 BOOK II. 
 
 THE DOCTRINE OF ENERGY AND THE LIVING WORLD. 
 GENERAL IDEAS OF LIFE. ALIMENTARY LIFE. 
 
 1. ENERGY IN GENERAL 57 
 
 IL ENERGY ix BIOLOGY 97 
 
 III. ALIMENTARY ENERGETICS . 116 
 
 BOOK III. 
 THE CHARACTERS COMMON TO LIVING BEINGS. 
 
 I. DOCTRINE OF VITAL UNITY 146 
 
 II. MORPHOLOGICAL UNITY OF LIVING BEINGS. . . 157 
 
 III. CHEMICAL UNITY OF LIVING BEINGS . . . . 173 
 
 IV. TWOFOLD CONDITIONING OF VITAL PHENOMENA. 
 
 IRRITABILITY 188 
 
 ix.
 
 X CONTENTS. 
 
 CHAP. PAGE 
 
 V. THE SPECIFIC FORM: ITS ACQUISITION, ITS REPARA- 
 
 TION - 199 
 
 VI. NUTRITION. FUNCTIONAL ASSIMILATION. FUNCTIONAL 
 
 DISTRIBUTION. ASSIMILATING SYNTHESIS . . 209 
 
 BOOK IV. 
 THE LIFE OF MATTER. 
 
 I. UNIVERSAL LIFE (OPINIONS OF THE PHILOSOPHERS 
 AND POETS). CONTINUITY BETWEEN BRUTE BODIES 
 AND LIVING BODIES. ORIGIN OF THE PRINCIPLE OF 
 
 CONTINUITY 239 
 
 II. ORIGIN OF LIVING MATTER IN BRUTE MATTER . . 249 
 
 III. ORGANIZATION AND CHEMICAL COMPOSITION OF LIVING 
 
 MATTER AND BRUTE MATTER 255 
 
 IV. EVOLUTION AND MUTABILITY OF LIVING MATTER AND 
 
 BRUTE MATTER ........ 259 
 
 V. THE COMPOSITION OF THE SPECIFIC FORM. LIVING 
 
 BODIES AND CRYSTALS. CICATRIZATION . . . 281 
 VI. NUTRITION IN THE LIVING BEING AND IN THE 
 
 CRYSTAL 290 
 
 VII. GENERATION IN BRUTE BODIES AND LIVING BODIES. 
 
 SPONTANEOUS GENERATION 294 
 
 BOOK V. 
 
 SENESCENCE AND DEATH. 
 I. THE DIFFERENT POINTS OF VIEW FROM WHICH DEATH 
 
 MAY BE REGARDED . 307 
 
 II. CONSTITUTION OF THE ORGANISMS. PARTIAL DEATH. 
 
 COLLECTIVE DEATHS 312 
 
 III. PHYSICAL AND CHEMICAL CHARACTERISTICS OF 
 
 CELLULAR DEATHS. NECROBIOSIS .... 321 
 
 IV. APPARENT PERENNITY OF COMPLEX INDIVIDUALS . 330 
 V. IMMORTALITY OF THE PROTOZOA AND OF SLIGHTLY 
 
 DIFFERENTIATED CELLS 334 
 
 VI. LETHALITY OF THE METAZOA AND OF DIFFF.RENTIATED 
 
 CELLS 340 
 
 VII. MAN. THE INSTINCT OF LIFK AND THE INSTINCT OF 
 
 DEATH 345 
 
 INDEX 361
 
 LIFE AND DEATH. 
 
 BOOK I. 
 
 THE FRONTIERS OF SCIENCE GENERAL THEORIES 
 OF LIFE AND DEATH THEIR SUCCESSIVE 
 TRANSFORMATIONS. 
 
 Chapter I. Early Theories. II. Animism. III. Vitalism. 
 IV. Monism. V. Emancipation of Scientific Research 
 from the Yoke of Philosophy. 
 
 CHAPTER I. 
 
 EARLY THEORIES. 
 
 Animism Vitalism The Physico-Chemical Theory Their 
 Survival and Transformations. 
 
 THE fundamental theories of science are but the ex- 
 pression of its most general results. What, then, is 
 the most general result of the development of 
 physiology or biology that is to say, of that depart- 
 ment of science which has life as its object? What 
 glimpse do we get of the fruit of all our efforts ? The 
 answer is evidently the response to that essential 
 question What is Life ? 
 
 There are beings which we call living beings ; there 
 are bodies which have never been alive inanimate 
 bodies ; and there are bodies which are no longer 
 i
 
 2 LIFE AND DEATH. 
 
 alive dead bodies. The fact that we use these terms 
 implies the idea of a common attribute, of a quid pro- 
 firium, life, which exists in the first, has never existed 
 in the second, and has ceased to exist in the last. Is 
 this idea correct? Suppose for a moment that this 
 is so, that this implicit supposition has a foundation, 
 and that there really is something which corresponds 
 to the word "life" Must we then wait for the last 
 days of physiology, and in a measure for its last 
 word before we know what is hidden behind this 
 word, " life " ? 
 
 Yes, no doubt positive science should be precluded 
 from dealing with questions of this kind, which are 
 far too general. It should be limited to the study of 
 second causes. But, as a matter of fact, scientific 
 men in no age have entirely conformed to this pro- 
 visional or definitive antagonism. As the human 
 mind cannot rest satisfied with indefinite attempts, or 
 with ignorance pure and simple, it has always asked, 
 and even now asks, from the spirit of system the 
 solution which science refuses. It appeals to philo- 
 sophical speculation. Now, philosophy, in order to 
 explain life and death, offers us hypotheses. It offers 
 us the hypotheses of thirty, of a hundred, or two 
 thousand years ago. It offers us animism ; vitalism 
 in its two forms, unitary vitalism or the doctrine of 
 vital force, and dismembered vitalism or the doctrine 
 of vital properties ; and finally, materialism, a 
 mechanical theory, unicism or monism, to give it 
 all its names i.e., the physico-chemical doctrine of 
 life. There are, therefore, at the present day, in 
 biology, representatives of these three systems which 
 have never agreed on the explanation of vital 
 phenomena namely, animists, vitalists, and monists.
 
 EARLY THEORIES. 3 
 
 But it is pretty clear that there must have been 
 some change between yesterday and to-day. Not 
 in vain has general science and biology itself made 
 the progress which we know has been made since 
 the Renaissance, and especially during the course 
 of the nineteenth century. The old theories have 
 been compelled to take new shape, such parts as have 
 become obsolete have been cut away, another 
 language is spoken in a word, the theories have 
 become rejuvenated. The neo-animists of our day, 
 Chauffard in 1878, von Bunge in 1889, and more 
 recently Rindfleisch, do not hold exactly the same 
 views as Aristotle, St. Thomas Aquinas, or Stahl. 
 Contemporary neo-vitalists, physiologists like Heiden- 
 hain, chemists like Armand Gautier, or botanists like 
 Reinke do not between 1880 and 1900 hold the same 
 views as Paracelsus in the fifteenth century and Van 
 Helmont in the seventeenth, as Barthez and Bordeu at 
 the end of the eighteenth, or as Cuvier and Bichat at 
 the beginning of the nineteenth century. Finally, the 
 mechanicians themselves, whether they be disciples 
 of Darwin and Haeckel, as most biologists of our 
 own time, or disciples of Lavoisier, as most physio- 
 logists of the present day, have passed far beyond the 
 ideas of Descartes. They would reject the coarse 
 materialism of the celebrated philosopher. They 
 would no longer consider the living organism as a 
 machine, composed of nothing but wheels, springs, 
 levers, presses, sieves, pipes, and valves ; or again 
 of matrasses, retorts, or alembics, as the iatro- 
 mechanicians and would-be chemists of other days 
 believed. 
 
 All that is changed, at any rate in form. If we look 
 back only thirty or forty years we see that the old
 
 4 LIFE AND DEATH. 
 
 doctrines have undergone more or less profound 
 modifications. The changes of form, which have been 
 made necessary by the acquisitions of contemporary 
 science, enable us to appreciate its progress. They 
 enable us to give an account of the progress of 
 biology, and for this reason they deserve to be 
 examined with some attention. It is into this 
 examination that I ask my readers to accompany me.
 
 CHAPTER II. 
 
 ANIMISM. 
 
 The Common Characteristic of Animism and Vitalism : the 
 Human Statue Primitive Animism Stahl's Animism 
 First Objection with Reference to the Relation between 
 Soul and Body Second Objection : the Unconscious 
 Character of Vital Operations Twofold Modality of the 
 Soul Continuity of the Soul and Life. 
 
 CHILDREN are taught that there are three kingdoms 
 in Nature the mineral kingdom and the two living 
 kingdoms, animal and vegetable. This is the whole 
 of the sensible world. Then above all that is placed 
 the world of the soul. School-boys therefore have 
 no doubts on the doctrines that we discuss here. 
 They have the solution. To them there are three 
 distinct spheres, three separate worlds matter, life, 
 and thought. 
 
 It is this preconceived idea that we are about to 
 examine. Current opinion solves a priori the question 
 of the fundamental homogeneity or lack of resem- 
 blance of these three orders of phenomena the 
 phenomena of inanimate nature, of living nature, and 
 of the thinking soul. Animism, vitalism, and monism 
 are, in reality, different ways of looking at them. 
 They are the different answers to this question : 
 Are vital, psychic, and physico-chemical manifesta- 
 tions essentially distinct? Vitalists distinguish be- 
 5
 
 LIFE AND DEATH. 
 
 tween life and thought, animists identify them. In 
 the opposite camp mechanicians, materialists, or 
 monists make the same mistake as the animists, but 
 to that mistake they add another : they assimilate the 
 forces at play in animals and plants to the general 
 forces of the universe; they confuse all three soul, 
 life, inanimate nature. 
 
 These problems belong on many sides to meta- 
 physical speculation. They have been discussed by 
 philosophers ; they have been solved from time im- 
 memorial in different ways, for reasons and by argu- 
 ments which it is not our purpose to examine here, 
 and which, moreover, have not changed. But on 
 some sides they belong to science, and must be tested 
 in the light of its progress. Cuvier and Bichat, for 
 example, considered that the forces in action in 
 living beings were not only different from physico- 
 mechanical forces, but were utterly opposed to them. 
 We now know that this antagonism does not exist. 
 
 The preceding doctrines, therefore, depend up to a 
 certain point on experiment and observation. They 
 are subject to the test of experiment and observation 
 in proportion as the latter can give us information on 
 the degree of difference or analogy presented by 
 psychic, vital, and physico-chemical facts. Now, 
 scientific investigations have thrown light on these 
 points. There is no doubt that the analogies and 
 the resemblances of these three orders of manifesta- 
 tions have appeared more and more numerous and 
 striking as our knowledge has advanced. Hence it is 
 that animism can count to-day but very few advocates 
 in biological science. Vitalism in its different forms 
 counts more supporters, but the great majority have 
 adopted the physicorchemical theory.
 
 ANIMISM. 7 
 
 Both animism and vitalism separate from matter a 
 directing principle which guides it. At bottom they 
 are mythological theories somewhat similar to the 
 paganism of old. The fable of Prometheus or the 
 story of Pygmalion contains all that is essential. 
 An immaterial principle, divine, stolen by the 
 Titan from Jupiter, or obtained from Venus by the 
 Cypriot sculptor, descends from Olympus and 
 animates the form, till then inert, which has been 
 carved in the marble or modelled in the clay. In a 
 word, there is a human statue. It receives a breath 
 of heavenly fire, a vital force, a divine spark, a soul, 
 and behold! it is alive. But this breath can also 
 leave it An accident happens, a clot in a vein, a 
 grain of lead in the brain the life escapes, and all 
 that is left is a corpse. A single instant has proved 
 sufficient to destroy its fascination. This is how all 
 men picture to their minds the scene of death. The 
 breath escapes ; something flies away, or flows away 
 with the blood. The happy genius of the Greeks 
 conceived a graceful image of this, for they re- 
 presented the life or the soul in the form of a butter- 
 fly (Psyche) leaving the body, an ethereal butterfly, 
 as it were, opening its sapphire wings. 
 j^ But what is this subtle and transient guest of the 
 human statue, this passing stranger which makes of 
 the living body an inhabited house? According to 
 the animists it is the soul itself, in the sense in 
 which the word is understood by philosophers ; the 
 immortal and reasoning soul To the vitalists it is 
 an inferior, subordinate soul ; a soul, as it were, of 
 secondary majesty, the vital force, or in a word, life. 
 
 Primitive Animism. Animism is the oldest and 
 most primitive of the conceptions presented to the
 
 8 LIFE AND DEATH. 
 
 human mind. But in so far as it is a co-ordinated 
 doctrine, it is the most recent. In fact it only 
 received its definitive expression in the eighteenth 
 century, from Stahl, the philosopher-physician and 
 chemist. 
 
 According to Tylor, one of the first speculations of 
 primitive man, of the savage, is as to the difference 
 between the living body and the corpse. The former 
 is an inhabited house, the latter is empty. To such 
 rudimentary intellects the mysterious inhabitant is a 
 kind of double or duplicate of the human form. It is 
 only revealed by the shadow which follows the body 
 when illuminated by the sun, by the image of its 
 reflection in the water, by the echo which repeats the 
 voice. It is only seen in a dream, and the figures 
 which people and animate our dreams are nothing 
 but these doubled, impalpable beings. Some savages 
 believe that at the moment of death the double, or 
 the soul, takes up its residence in another body. 
 Sometimes each individual possesses, not one of these 
 souls, but several. According to Maspero, the 
 Egyptians counted at least five, of which the 
 principle, the ka or double, would be the aeriform or 
 vaporous image of the living form. Space is peopled 
 by souls on their travels, which leave one set of bodies 
 to occupy another set. After having been the cause 
 of life in the bodies which they animated, they 
 react from without on other beings, and are the 
 cause of all sorts of unexpected events. They are 
 benevolent or malevolent spirits. 
 
 Analogy inevitably leads simple minds to extend 
 the same ideas to animals and plants ; in a word, to 
 attribute souls to everything alive, souls more or less 
 nomadic, wandering, or interchangeable, as is taught
 
 AXIMISM. 9 
 
 in the doctrine of metempsychosis. Mons. L. Errera 
 points out that this primitive, co-ordinated, hier- 
 archized doctrine meet subject for the poet's art is 
 the basis of all ancient mythologies. 
 
 TJie Animism of StaJd. Modern animism was 
 much more narrow in scope It was a medical theory 
 i.e. almost exclusive to man. Stahl had adopted it 
 in a kind of reaction against the exaggerations of the 
 mechanical school of his time. According to him, the 
 life of the body is due to the intelligent and reason- 
 ing soul. It governs the corporeal substance and 
 directs it towards an assigned end. The organs are 
 its instruments. It acts on them directly, without 
 intermediaries. It makes the heart beat, the muscles 
 contract, the glands secrete, and all the organs per- 
 form their functions. Nay more, it is itself the 
 architectonic soul, which has constructed and which 
 maintains the body which it rules. It is the metis 
 agitat molem of Virgil. 
 
 It is remarkable that these ideas, so excessively 
 and exaggeratedly spiritualistic, should have been 
 brought forward by a chemist and a physician, while 
 ideas completely opposed to these were admitted by 
 philosophers like Descartes and Leibniz, who were 
 decided believers in the spirituality of the soul. Stahl 
 had been Professor of Medicine at the University of 
 Halle, physician to the Duke of Saxe- Weimar, and 
 later to the King of Prussia. He left an important 
 medical and chemical work, both theoretical and 
 practical. He is the author of the celebrated theory 
 of phlogiston, which held its ground in chemistry up 
 to the time of Lavoisier. He died about 1734. 
 
 Animism survived him for some time, maintained 
 by the zeal of a few faithful disciples. But after the
 
 IO LIFE AND DEATH. 
 
 witty mockery of Bordeu, 1 in 1742, it began to decay. 
 We must, however, point out that an attempt to revive 
 this theory was made in 1878 by a well-known doctor 
 of the last generation, E. Chauffard. While preserving 
 the essential features of the theory, this learned 
 physician proposed to bring it into harmony with 
 modern science, and to free it from all the reproaches 
 which had been levelled at it. 
 
 The Animism of E, Chauffard. These reproaches 
 were numerous. The most serious is of a philosophic 
 nature. It rises from the difficulty of conceiving a 
 direct and immediate action of the soul, considered as 
 a spiritual principle, upon the matter of the body. 
 There is such an abyss hewn by the philosophic 
 mind itself between soul and body, that it is im- 
 possible to imagine any relation between them. We 
 can only get a glimpse of how the soul might become 
 an instrument of action. 
 
 This was the problem which sorely tried the genius 
 f Leibniz. Descartes, in earlier days, attacked it 
 vigorously, like an Alexander cutting the Gordian 
 knot He separated the soul from the body, and 
 made of the latter a pure machine in the government 
 of which the soul had no part. He attributed all the 
 known manifestations of vital activity to inanimate 
 forces. Leibniz, also, was compelled to reject all 
 action, all contact, all direct relation, every real bond 
 between soul and body, and to imagine between them 
 
 1 In a thesis presented in 1742 at Montpellier, Bordeu, then 
 only twenty years of age, made game of the tasks imposed by 
 animists on the Soul, "which has to moisten the lips when 
 required;" or, "whose anger produces the symptoms of certain 
 diseases;" or again, "which is prevented by the consequences 
 of original sin from guiding and directing the body."
 
 II 
 
 a purely metaphysical relation pre-established har- 
 mony: u Soui and body agree in virtue of this 
 harmony, the harmony pre-established since the 
 creation, and in no way by a mutual, actual, physical 
 influence. Everything that takes place in the soul 
 takes place as if there were no body, and so every- 
 thing takes place in the body as if there were no 
 soul" At this point we almost reach a scientific 
 materialism. It is easy for the materialist to break 
 this frail tie of pre-established harmony which so 
 loosely unites body and soul, and to exhibit the 
 organism as under the sole control of universal 
 mechanics and physics. 
 
 Thus the weak point of Stahl's animism was the 
 supposition of a direct action exercised on the organ- 
 ism by a distinct, heterogeneous, spiritual principle. 
 
 ChaufTard has endeavoured to avoid this pitfalL In 
 conformity with modern ideas, he has brought together 
 what the ancient philosophers and Stahl himself 
 separated the activity of matter and the activity of 
 the soul "Thought, action, function, are embraced 
 in an indissoluble union." This is the classical bat 
 not very lucid theory which has been so often re- 
 produced Hvmo foetus est anima -rirtns which 
 Bossuet has expressed in the celebrated formula: 
 "Soul and body form a natural whole." 
 
 A second objection raised against animism is that 
 the soul acts consciously, with reflection, and with 
 volition, and that its essential attributes are not found 
 in most physiological phenomena, which, on the con- 
 trary are automatic, involuntary, and unconscious. 
 The contradictory nature of these characteristics has 
 obliged vitalists to conceive of a vital principle 
 distinct from thought Chaufiard, agreeing here with
 
 12 LIFE AND DEATH. 
 
 Boullier, Tissot, and Stahl himself, does not accept 
 this distinction ; he refuses to shatter the unity of the 
 vivifying and thinking principle. He prefers to at- 
 tribute to the soul two modes of action : the one 
 which is exercised on the acts of thought, and hence 
 it proceeds consciously, with reflection, and with 
 volition ; the other exercising control over the physio- 
 logical phenomena which it governs, " by unconscious 
 impressions, and by instinctive determinations, obeying 
 primordial laws." This soul is hardly in keeping with 
 his definition of a conscious, reflecting, and voluntary 
 principle; it is a new soul, a somatic soul, singularly 
 akin to that racJiidian soul which, according to 
 Pfliiger, a well-known German physiologist, resides 
 in each segment of the spinal marrow, and is respon- 
 sible for reflex movements. 
 
 Twofold Modality of the Soul. This twofold 
 modality of the soul, this duality admitted by Stahl 
 and his disciples, was repugnant to many thinkers, 
 and it is this repugnance that gave rise to the vitalistic 
 school. It appeared to them to be a heresy tainted 
 by materialism and so it was. In this lay the 
 strength and the weakness of animism. It admits 
 of a unique animating principle for all the manifes- 
 tations of the living being, for the higher facts in the 
 realm of thought, and for the lower facts connected 
 with the body. It throws down the barriers which 
 separate them. It fills up the gap between the 
 different forms of human activity, and assimilates 
 them the one to the other. 
 
 Now this is precisely what materialism does. It, 
 too, reduces to a single order the psychical and physi- 
 ological phenomena, between which it no longer 
 recognizes anything but a difference of degree,
 
 ANIMISM. 13 
 
 thought being only a maximum of the vital move- 
 ment, or life a minimum of thought. In truth, the 
 aims of the two schools are diametrically opposed ; 
 the one claims to raise corporeal activity to the 
 dignity of thinking activity, and to spiritualize the 
 vital fact ; the other lowers the former to the level of 
 the latter and materializes the psychic fact. But, 
 though the intentions are different, the result is 
 identical. Spiritualistic monism inclines towards 
 materialistic monism. One step more, and the soul, 
 confused with life, will be confused with physical 
 forces. 
 
 On the other hand, twofold modality has this 
 advantage, that it escapes the objection drawn from 
 the existence of so many living beings to which a. 
 thinking soul cannot be attributed ; an anencephalous 
 foetus, the young of the higher animals, the lower 
 animals and plants, living without thought, or with a 
 minimum of real, conscious thought The advocate 
 of animism replies that this physiological activity is 
 still a soul, but one which is barely aware of its 
 existence a gleam of consciousness. In this theory, 
 the knowledge of self, the consciousness, is of all 
 degrees. On the other hand, in the eyes of the 
 vitalist, it is an absolute fact which allows of no 
 attenuation, of no middle course between the being 
 and the non-being. 
 
 It is this conception of the continuity of the soul and 
 life, it is the affirmation of a possible lowering of the 
 complete consciousness down to a mere gleam of know- 
 ledge, and finally down to unconscious vital activity, 
 which saved animism from complete shipwreck. That 
 is why this ancient doctrine finds, even in the present 
 day, a few rare supporters. An able German scientist,
 
 14 LIFE AND DEATH. 
 
 G. von Bunge, well known for his researches in physio- 
 logical chemistry, professes animistic views in a work 
 which appeared in 1889. He attributes to organized 
 beings a guiding principle, a kind of vital soul. A 
 distinguished naturalist, Rindfleisch, of Liibeck, has 
 likewise taken his place among the advocates of what 
 we may call neo-animism.
 
 CHAPTER III. 
 VITALISM. 
 
 ks Extreme Forms Early Vitalism, and Modern Neo-vitalism 
 Advantage of distinguishing between Soul and Life 
 $ i. The Vitalism of Barthez Its Extension The Seat of 
 the Vital Principle The Vital Knot The Vital Tripod- 
 Decentralisation of the Vital Principle 2. The Doctrine 
 of Vital Properties Galen, Van Helmont, Xavier Bichat, 
 and Cuvier Vital and Physical Properties antagonistic 
 3. Scientific Neo-vitalism Heidenhain 4. Philo- 
 sophical Neo-vitalism Reinke. 
 
 Extreme Forms: Early Vitalism and Modern 
 vitalism. Contemporary neo-vitalism has weakened 
 primitive vitalism in some important points. The 
 latter made of the vital fact something quite specific, 
 irreducible either to the phenomena of general physics 
 or to those of thought. It absolutely isolated life, 
 separating it above from the soul, and below from in- 
 animate matter. This sequestration is nowadays 
 much less rigorous. On the psychical side the barrier 
 remains, but it is lowered on the material side. The 
 neo-vitalists of to-day recognize that the laws of 
 physics and chemistry are observed within, as well as 
 without, the living body; the same natural forces' 
 intervene in both, only they are "otherwise directed." 
 
 The vital principle of early times was a kind of 
 anthromorphic, pagan divinity. To Aristotle, this 
 force, the anima, the Psyche, worked, so to speak, with 
 15
 
 l6 LIFE AND DEATH. 
 
 human hands. According to the well-known ex- 
 pression, its situation in the human body corresponds 
 to that of a pilot on a vessel, or to that of a sculptor 
 or his assistant before the marble or clay. And, in 
 fact, we have no other clear image of a cause external 
 to the object. (We have no other representation of a 
 force external to matter than that which is offered by 
 the craftsman making an object, or in general by the 
 human being with his activity, free, or supposed to be 
 free, and directed towards an end to be realized./ 
 
 Personifications of this kind, the mythological 
 entities, the imaginary beings, the ontological fictions, 
 which ever filled the stage in the mind of our pre- 
 decessors, have definitely disappeared ; no longer have 
 they a place in the scientific explanations of our time. 
 The neo-vitalists replace them by the idea of direction, 
 which is another form of the same idea of finality. 
 The series of second causes in the living being seems 
 to be regulated in conformity with a plan, and directed 
 with a view to carrying it out. The tendency which 
 exists in every being to carry out this plan, that is to 
 say, the tendency towards its end, gives the impulse 
 that is necessary to carry it out. Neo-vitalists claim 
 that vital force directs the phenomena which it does not 
 produce, and which are in reality carried out by the 
 general forces of physics and chemistry. 
 
 Thus, the directing impulse, considered as really 
 active, is the last concession of modern vitalism. If 
 we go further, and if we refuse to the directing idea 
 executive power and efficient activity, the vital 
 principle is weakened, and we abandon the doctrine. 
 We can no longer invoke it. We cease to be vitalists 
 if the part played by the vital principle is thus far 
 restricted. At first it was both the author of the
 
 VITALISM. 17 
 
 plan and the universal architect of the organic edifice ; 
 it is now only the architect directing his workmen, 
 and they are physical and chemical agents. It is now 
 reduced to the plan of the work, and even this plan 
 has no objective existence; it is now only an idea. 
 It has only a shadow of reality. To this it has been 
 reduced by certain biologists. For this we may thank 
 Claude Bernard; and he has thereby placed himself 
 outside and beyond the weakest form of vitalism. He 
 did not consider the idea of direction as a real 
 principle. The connection of phenomena, their 
 harmony, their conformity to a plan grasped by the 
 intellect, their fitness for a purpose known to the 
 intellect, are to him but a mental necessity, a meta- 
 physical concept. The plan which is carried out has 
 only a subjective existence; the directing force has no 
 efficient virtue, no executive power; it does not 
 emerge from the intellectual domain in which it took 
 its rise, and does not " react on the phenomena which 
 enabled the mind to create it." 
 
 It is between these two extreme incarnations of the 
 vital principle, on the one hand an executive agent, on 
 the other a simple directing plan, that the motley pro- 
 cession of vitalist doctrines passes on its way. At the 
 point of departure we have a vital force, personified, 
 acting, as we have stated, as if with human hands 
 fashioning obedient matter; this is the pure and 
 primitive form of the theory. At the other extreme we 
 have a vital force which is now only a directing idea, 
 without objective existence, and without an executive 
 role; a mere concept by which the mind gathers 
 together and conceives of a succession of physico- 
 chemical phenomena. On this side we are brought 
 into touch with monism.
 
 l8 LIFE AND DEATH. 
 
 The Reasons given by the Vitalists for distinguishing 
 Soul from Life. It is, in particular, on the opposite 
 side, in the psychical world, that the early vitalists pro- 
 fessed to entrench themselves. We have just seen that 
 their doctrines were not so subtle as those of to-day ; 
 the vital principle to them was a real agent, and not an 
 ideal plan in the process of being carried out. But 
 they distinguished this spiritual principle from another 
 co-existent with it in superior living beings at any 
 rate, in man : the thinking soul. They boldly dis- 
 tinguished between them, because the activity of the 
 one is manifested by knowledge and volition, while 
 on the contrary, the manifestations of the other for 
 the most part escape both consciousness and volition. 
 
 In fact, we know nothing of what goes on in the 
 normal state of our organs. Their perfect performance 
 of their functions is translated to us solely by an 
 obscure feeling of comfort. We do not feel the beat- 
 ing of the heart, the periodic dilations of the arteries, 
 the movements of the lungs or intestine, the glands at 
 their work of secretion, or the thousand reflex mani- 
 festations of our nervous system. The soul, which is 
 conscious of itself, is nevertheless ignorant of all this 
 vital movement, and is therefore external to it. 
 
 This is the view of all the philosophers of antiquity. 
 Pythag.oras distinguished the real soul, the thinking 
 soul, the Nous, the intelligent and immortal principle, 
 characterized by the attributes of consciousness and 
 volition, from the vital principle, the Psyche, which 
 gives breath and animation to the body, and which is 
 a soul of secondary majesty, active, transient, and 
 mortal. Aristotle did the same. On the one side he 
 placed the soul properly so called, the Nous or 
 intellect that is to say, the understanding with its
 
 VITALISM. 19 
 
 rational intelligence ; on the other side was the 
 directing principle of life, the irrational and vegeta- 
 tive Psyche. 
 
 This distinction agrees with the fact of the diffusion 
 of life. Life does not belong to the superior animals 
 alone, and to the man in whom we can recognize a 
 reasoning soul. It is extended to the vast multitude 
 of humbler beings to which such lofty faculties cannot 
 be attributed, the invertebrates, microscopic animals, 
 and plants. The advantage is compensated for by 
 the inconvenience of breaking down all continuity 
 between the soul and life; a continuity which is the 
 principle of the two other doctrines, animism and 
 monism, and which is, we may say, the very aim and 
 the unquestionable tendency of science. 
 
 As for classical philosophy, it satisfies the necessity 
 of establishing the unity of the living being, />., of 
 bringing into harmony soul and body, but in a 
 .manner which we need not here discuss. It at- 
 tributes to the soul several modalities, several distinct 
 powers: powers of the vegetative life, powers of the 
 sensitive life, and powers of the intellectual life. And 
 this other solution of the problem would be, in the 
 opinion of M. Gardair, in complete agreement with 
 the doctrines of St. Thomas Aquinas. 
 
 i. THE VITALISM OF BARTHEZ : ITS EXTENSION. 
 
 Vitalism reached its most perfect expression in the 
 second half of the eighteenth century in the hands of 
 the representatives of the Montpellier school Bordeu, 
 Grimaud, and Barthez. The last, in particular, 
 contributed to the prevalence of the doctrine in
 
 20 LIFE AND DEATH. 
 
 medical circles. A man of profound erudition, a 
 collaborates with d'Alembert in the Encyclopedia, 
 he exercised quite a preponderant influence on the 
 medicine of his day. Stationed at Paris during part 
 of his career, physician to the King and the Duke of 
 Orleans, we may say that he supported his theories by 
 every imaginable influence which might contribute to 
 their success. In consequence of this, the medical 
 schools taught that vital phenomena are the immediate 
 effects of a force which has no analogues outside the 
 living body. This conception reigned unchallenged 
 up to the days of Bichat 
 
 After Bichat, the vitalism of Barthez, more or less 
 modified by the ideas of the celebrated anatomist, 
 continued to hold its own in all the schools of 
 Europe until about the middle of the nineteenth 
 century. Johannes Mtiller, the founder of physiology 
 in Germany, admitted, about 1833, the existence of a 
 unique vital force "aware of all the secrets of the 
 forces of physics and chemistry, but continually in 
 conflict with them, as the supreme cause and regulator 
 of all phenomena." When death came, this principle 
 disappeared and left no trace behind. One of the 
 founders of biological chemistry, Justus Liebig, who 
 died in 1873, shared these ideas. The celebrated 
 botanist, Candolle, who lived up to 1893, taught at 
 the beginning of his career that the vital force was one 
 of the four forces ruling in nature, the other three 
 being attraction, affinity, and intellectual force. 
 Flourens, in France, made the vital principle one of 
 the five properties of forces residing in the nervous 
 system. Another contemporary, Dressel, in 1883, 
 endeavoured to bring back into fashion this rather 
 primitive, monistic, and efficient vitalism.
 
 VITALISM. 21 
 
 T/K Scat of the Vital Principle. Meanwhile, 
 another question was asked with reference to this 
 vital principle. It was a question of ascertaining its 
 seat: or, in other words, of finding its place in the 
 organism. Is it spread throughout the organism, or is 
 it situated in some particular spot from which it acts 
 upon every part of the body? Van Helmont, a cele- 
 brated scientist at the end of the sixteenth century, 
 who was both physician and alchemist, gave the first 
 and rather quaint solution of this difficult}'. The vital 
 principle, according to him, was situated in the 
 stomach, or rather in the opening of the pylorus. It 
 was the concierge, so to speak, of the stomach. The 
 Hebrew idea was more reasonable. The life was 
 connected with the blood, and was circulated with it 
 by means of all the veins of the organism. It escaped 
 from a wound at the same time as the liquid blood. 
 It is clear that in this belief we see why the Jews were 
 forbidden to eat meat which had not been bled. 
 
 T/u Vital Knot. In 1748 a doctor named Lorry 
 found that a very small wound in a certain region of 
 the spinal marrow brought on sudden death. The 
 position of this remarkable point was ascertained in 
 1812 by Legallois, and more accurately still by 
 Flourens in 1827. It is situated in the rachidian 
 bulb, at the level of the junction of the neck and the 
 head; or more precisely, on the floor of the fourth 
 ventricle, near the origin of the eighth pair of cranial 
 nerves. This is what was called the vital knot. 
 Upon the integrity of this spot, which is no bigger 
 than the head of a pin, depends the life of the animal. 
 Those who believed in a localisation of the vital 
 principle thought that they had found the seat 
 desired ; but for that to be so the destruction of this
 
 22 LIFE AND DEATH. 
 
 spot must be irremediable, and must necessarily cause 
 death. But if the vital knot be destroyed, and 
 respiration ^ be artificially induced by means of a 
 bellows, the animal resists: it continues to live. It is 
 only the nervous stimulating mechanism of the 
 respiratory movements which has been attacked in 
 one of its essential parts. 
 
 Life, therefore, resides no more in this point than it 
 does in the blood or in the stomach. Later experi- 
 ment has shown that it resides everywhere, that each 
 organ enjoys an independent life. Each part of the 
 body is, to use Bordeu's strong expression, "an animal 
 in an animal" '; or to adopt the phrase due to Bichat, 
 *' a particular machine witliin tJie general machine" 
 
 The Vital Tripod. What then is life, or, in other 
 words, what is the biological activity of the individual, 
 of the animal, of man ? It is clearly the sum total, or 
 rather, the harmony of these partial lives of the 
 different organs. But in this harmony it seems that 
 there are certain instruments which dominate and 
 sustain the others. There are some whose integrity 
 is more necessary to the preservation of existence and 
 health, and of which any lesion makes death more 
 inevitable. They are the lungs, the heart, and the 
 brain. Death always ensues, said the early doctors, if 
 any one of these three organs be injured. Life 
 depends, therefore, on them, as if upon a three-legged 
 support. Hence the idea of the vital tripod. It is no 
 longer a single seat for the vital principle, but a kind 
 of throne on three-supports. Life is decentralized. 
 
 This was only the first step, very soon followed by 
 many others, in the direction of vital decentralization. 
 (Experiment showed, in fact, that every organ separated 
 Ifrom the body will continue to live if provided with
 
 VITALISM. 23 
 
 the proper conditions^ And here, it is not only a 
 question of inferior beings; of plants that are pro- 
 pagated by slips; of the hjdra which Trembley cut 
 into pieces, each of which generated a complete hydra ; 
 of the nais which C Bonnet cut up into sections, each 
 of which reconstituted a complete annelid. There is 
 no^ exception to the.jule. 
 
 Decentralization of the Vital Principle. The result 
 is the same in the higher vertebrates, only the experi- 
 ment is much more difficult. At the Physiological 
 Congress of Turin in 1901, Locke showed the heart of 
 a hare, extracted from the body of the animal, and 
 beating for hours as energetically and as regularly as 
 if it were in its place. He suspended it in the air of 
 a room at the normal temperature, the sole condition 
 being that it was irrigated with a liquid composed of 
 certain constituents. The animal had been dead some 
 time. More recently Kuliabko has shown in the same 
 way the heart of a man still beating, although the 
 man had been dead some eighteen hours. The same 
 experiment is repeated in any physiological labora- 
 tory, in a much easier manner, with the heart of a 
 tortoise This organ, extracted from the body, fitted 
 up with rubber tubes to represent its arteries and 
 veins, and filled with the defibrinated blood of a horse 
 or an ox taken from the slaughter-house, works for 
 hours and days pumping the liquid blood into its 
 rubber aorta, just as if it were pumping it into the 
 living aorta. 
 
 But it is unnecessary to multiply examples. Every 
 organ can be made to live for a longer or shorter 
 period even though removed from its natural position ; 
 muscles, nerves, glands, and even the brain itself. 
 Each organ, each tissue therefore enjoys an inde- 
 
 3
 
 24 LIFE AND DEATH. 
 
 pendent existence ; it lives and works for itself. 
 No doubt it shares in the activity of the whole, but 
 it may be separated therefrom without being thereby 
 placed in the category of dead substances. For each 
 aliquot part of the organism there is a partial life and 
 a partial death. 
 
 This decentralization of the vital activity is finally 
 extended in complex beings from the organs to the 
 tissues, and from the tissues to the anatomical 
 elements the cells. The idea of decentralization 
 has given birth to the second form of vitalism, a 
 softened down and weakened form namely, pluri- 
 vitalism, or the theory of vital properties. 
 
 2. THE THEORY OF VITAL PROPERTIES. 
 
 The advocates of the theory of vital properties have 
 cut up into fragments the monistic and indivisible 
 guiding principle of Bordeu and Barthez. They have 
 given it new currency pluri-vitalism. This theory 
 maintains the existence of spiritual powers of a lower 
 order, which control phenomena more intimately than 
 the vital principle did. These powers, less lofty in 
 their dignity than the rational soul of the animists, or 
 the soul of secondary majesty of the Unitarian 
 vitalists, are eventually incorporated in the living 
 matter of which they will then be no longer more 
 than the properties. Brought into closer connection 
 therefore with the sensible world, they will be more 
 in harmony with the spirit of research and with 
 scientific progress. 
 
 The defect of the earlier conceptions, their common 
 illusion, rose from their seeking the cause outside the
 
 VITALISM. 25 
 
 object, from their demanding an explanation of vital 
 phenomena from a principle external to living, 
 immaterial, and unsubstantial matter. Here this 
 defect is less marked. The pluri-vitalists will in turn 
 appeal to the vital properties as modes of activity, 
 inherent in the living substance in which and by which 
 they are manifested, and derived from the arrangement 
 of the molecules of this substance that is to say, from 
 its organization. This is almost the conception of 
 the present day. 
 
 But this progress will only be realized at the end of 
 the evolution of the pluri-vitalist theory. At the outset 
 this theory seems an exaggeration of its predecessor, 
 and a still more exaggerated form of the mythological 
 paganism with which it was reproached. The archeus, 
 the bias, the properties, the spirits all have at first 
 the effect of the genii or of the gods imagined by the 
 ancients to preside over natural phenomena, of 
 Neptune stirring up the waters of the sea, and of 
 Eolus unchaining the winds. These divinities of the 
 ancient world, the nymphs, the dryads, and the sylvan 
 gods, seem to be transported to the Middle Ages, to 
 that age of argument, that philosophical period of the 
 history of humanity, and there metamorphosed into 
 occult causes, immaterial powers, and personified 
 forces. 
 
 Galen. The first of the pluri-vitalists was Galen, 
 the physician of Marcus Aurelius, the celebrated 
 author of an Encyclopaedia of which the greater part 
 has been lost, and of which the one book preserved 
 held its own as the anatomical oracle and breviary 
 throughout the Middle Ages. According to Galen 
 the human machine is guided by three kinds of 
 spirits: animal spirits, presiding over the activity of
 
 26 LIFE AND DEATH. 
 
 the nervous system; vital spirits governing most of 
 the other functions; and finally, natural spirits 
 regulating the liver and susceptible of incorporation 
 in the blood. In the sixteenth century, in the time of 
 Paracelsus, Galen's spirits became Olympic spirits. 
 They still presided over the functional activity of the 
 organs, the liver, heart, and brain, but they also 
 existed in all the bodies of nature. 
 
 Van Helmont. Finally, the theory was laid down 
 by Van Helmont, physician, chemist, experimentalist, 
 and philosopher, endowed with a rare' and penetrating 
 intellect. Here we find many profound truths com- 
 bined with fantastic dreams. Refusing to admit the 
 direct action of an immaterial agent, such as the soul, 
 on inert matter, on the body, he filled up the abyss 
 which separated them by creating a whole hierarchy 
 of immaterial principles which played the part of 
 mediators and executive agents. At the head of this 
 hierarchy was placed the thinking and immortal soul ; 
 below was the sensitive and mortal soul, having for its 
 minister the principal archeus, the aura vitalis, a kind 
 of incorporeal agent, which is remarkably like the 
 vital principle, and which had its seat at the orifice of 
 the stomach. Below again were the subordinate 
 agents, the bias, or vulcans placed in each organ, and 
 intelligently directing its mechanism like skilful 
 workmen. 
 
 These chimerical ideas are not, however, so far 
 astray as the theory of vital properties. When we 
 see a muscle contract, we say that this phenomenon 
 is due to a vital property i.e., a property without any 
 analogue in the physical world, namely contractility, 
 In the same way the nerve possesses two vital 
 properties, excitability and conductibility, \t\\\z\\ Vulpian
 
 VITALISM. 27 
 
 proposed to blend into one, calling it neurility. These 
 are mere names, serving as a kind of shorthand; but 
 to those who believe that there is something real in it, 
 this something is not very far from the bias of Van 
 Helmont Vufcans, hidden in the muscle or the nerve, 
 are here detected by attraction, there by the pro- 
 duction and the propagation of the nervous influx; 
 that is to say, by phenomena of which we as yet 
 know no analogues in the physical world, but of 
 which we cannot say that they do not exist 
 
 X. BicJtat and G. Cuvier: Vital and Physical 
 Properties Antagonistic. The archeus and the bias of 
 Van Helmont were but a first rough outline of 
 vital properties. Xavier Bichat, the founder of general 
 anatomy, wearied of all these incorporeal entities, of 
 these unsubstantial principles with which biology was 
 encumbered, undertook to get rid of them by the 
 methods of the physicist and the chemist The physics 
 and the chemistry of his day referred phenomenal 
 manifestations to the properties of matter, gravity, 
 capillarity, magnetism, etc. Bichat did the same- 
 He referred vital manifestations to the properties of 
 living tissues, if not, indeed, of living matter. Of 
 these properties as yet but very few were known : 
 the irritability described by Glisson, which is the 
 excitability of current physiology ; and the irritability 
 of Haller, which is nothing but muscular contrac- 
 tility. Others had to be discovered. 
 
 There is no need to recall the mistake made by 
 Bichat and followed by most scientific men of his 
 time, such as Cuvier in France, and J. Miiller in 
 Germany, for the story has been told by Claude 
 Bernard. His mistake was in considering the vital 
 properties not only as distinct from physical properties
 
 28 LIFE AND DEATH. 
 
 but even as opposed to them. The one preserve the 
 body, the others tend to destroy it. They are always 
 in conflict. Life is the victory of the one; death is 
 the triumph of the other. Hence the celebrated 
 definition given by Bichat: "Life is the sum total of 
 functions which resist death," or the definition of the 
 Encyclopaedia: "Life is the contrary of death." 
 
 Cuvier has illustrated this conception by a graphic 
 picture. He represents a young woman in all the 
 health and strength of youth suddenly stricken by 
 death. The sculptural forms collapse and show the 
 angularities of the bones; the eyes so lately sparkling 
 become dull; the flesh tint gives place to a livid 
 pallor; the graceful suppleness of the body is now 
 rigidity, " and it will not be long before more horrible 
 changes ensue ; the flesh becomes blue, green, black, 
 one part flows away in putrid poison, and another 
 part evaporates in infectious emanations. Finally, 
 nothing is left but saline or earthy mineral principles, 
 all the rest has vanished." Now, according to Cuvier, 
 what has happened ? 
 
 These alterations are the effect of external agents, 
 air, humidity, and heat. They have acted on the 
 corpse just as they used to act on the living being ; 
 but before death their assault had no effect, because it 
 was repelled by the vital properties. Now that life 
 has disappeared the assault is successful. We know 
 now that external agents are not the cause of these 
 disorders. They are caused by the microbes of 
 putrefaction. It is against tJieni that the organs were 
 struggling, and not against physical forces. 
 
 The mistake made by Bichat and Cuvier was in- 
 excusable, even in their day. They were wrong not 
 to attach the importance they deserved to Lavoisier's
 
 VITALISM. 29 
 
 researches. He had asserted, apropos of animal heat 
 and respiration, the identity of the action of physical 
 agents in the living body and in the external world. 
 On the other hand, Bichat, by a flash of genius, de- 
 centralized life, dispersing the vital properties in the 
 tissues, or, as we should now say, in the living matter. 
 It was from the comparison between the constitution 
 and the properties of living matter and those of in- 
 animate matter that light was to come. 
 
 | 3. SCIENTIFIC XEO- VITALISM. 
 
 We can now understand the nature of modem 
 neo-vitalism. It borrows from its predecessor its 
 fundamental principle namely, the specificity of the 
 vital fact But this specificity is no longer essential, 
 it is only formal. The difference between it and the 
 physical fact grows less and almost vanishes. It con- 
 sists of a diversity of mechanisms or executive agents. 
 For example, digestion transforms the alimentary 
 starch in the intestines into sugar; the chemist does 
 the same in his laboratory, only he employs acids, 
 while the organism employs special agents, ferments, 
 in this case a diastase. It is a particular form of 
 chemistry, but still it is a chemistry. That is how 
 Claude Bernard looked at it. The vital fact was not 
 fundamentally distinguished from the physico-chemi- 
 cal fact, but only in form. 
 
 This expurgated and accommodated vitalism 
 (Claude Bernard pushed his concessions so far as to 
 call his doctrine " physico-chemical vitalism ") was re- 
 vived a few years ago by Chr. Bohr and Hetdenhain. 
 
 Other biologists, instead of attributing the difference
 
 30 LIFE AND DEATH. 
 
 between the phenomena of the two orders to the 
 manner of their occurrence, seem to admit the com- 
 plete identity of the mechanisms. It is no longer 
 then in itself, individually, that the vital act is 
 particularized, but in the manner in which it is 
 linked to others. The vital order is a series of 
 physico-chemical acts realizing an ideal plan. 
 
 Neo-vitalism has therefore assumed two forms, 
 one the more scientific and the other the more 
 philosophical. 
 
 Chr. Bohr and HeidenJiain. Its scientific form was 
 given to it by Chr. Bohr, an able physiologist at 
 Copenhagen, and by Heidenhain, a professor at 
 Breslau, who was one of the lights of contemporary 
 German physiology. The course of their researches 
 led these two experimentalists, working independ- 
 ently, to submit to fresh investigation the ideas of 
 Lavoisier and those of Bichat, on the relation of 
 physico-chemical forces to the vital forces. 
 
 It was by no means a question of a general 
 inquiry, deliberately instituted with the object of dis- 
 covering the part played respectively by physical and 
 physiological factors in the performance of the various 
 functions. Such an investigation would have taken 
 several generations to complete. No; the question 
 had only come up incidentally. Chr. Bohr had studied 
 with the utmost care the gaseous exchanges which 
 take place between the air and the blood in the lungs. 
 The gaseous mixture and the liquid blood are face 
 to face ; they are separated by thin membrane formed 
 of living cells. Will this membrane behave as an 
 inert membrane deprived of vitality, and therefore 
 obeying the physical laws of the diffusion of gases ? 
 Well ! no. It does not so behave. The most careful
 
 VITALISM. 31 
 
 measurements of pressures and of solubilities leave no 
 doubt in this respect. The living elements of the 
 pulmonary membrane must therefore intervene in 
 order to disturb the physical phenomenon. Things 
 happen as if the exchanged gases were subjected not 
 to a simple diffusion, a physical fact obeying certain 
 rules, but to a real secretion, a physiological or vital 
 phenomenon, obeying laws which are also fixed, but 
 different from the former. 
 
 On the other hand, Heidenhain was led about the 
 same time to analogous conclusions with respect 
 to the liquid exchanges which take place within 
 the tissues, between the liquids (lymphs) which 
 bathe the blood-vessels externally and the blood 
 which those vessels contain. The phenomenon is 
 very important because it is the prologue of the 
 actions of nutrition and assimilation. Here again, 
 the two factors of exchange are brought into relation 
 through a thin wall, the wall of the blood-vessel The 
 physical laws of diffusion, of osmosis, and of dialysis, 
 enable us to foretell what would take place if the 
 vitality of the elements of the wall did not intervene. 
 Heidenhain thought he observed that things took 
 place otherwise. The passage of the liquids is dis- 
 turbed by the fact that the cellular elements are aliire. 
 It assumes the characteristics of a physiological act, 
 and no longer those of a physical act Let us add 
 that the interpretation of these experiments is difficult, 
 and it has given rise to controversies which still 
 persist. 
 
 These two examples, around which others might be 
 grouped, have led certain physiologists to diminish the 
 importance of the physical factors in the functional 
 activity of the living being to the advantage of the
 
 32 LIFE AND DEATH. 
 
 physiological factors. It would therefore seem that 
 the vital force, to use a rather questionable form 
 of language, withdraws in a certain measure the 
 organized being from the realm of physical forces 
 and this conclusion is one form of contemporary 
 neo-vitalism. 
 
 4. PHILOSOPHICAL NEO-VITALISM. 
 
 Contemporary neo-vitalism has assumed another 
 form, more philosophical than scientific, by which it is 
 brought closer to vitalism, properly so called. We 
 should like to mention the experiment of Reinke, 1 
 in Germany. Reinke is a botanist of distinction, who 
 distinguishes the speculative from the positive domain 
 of science, and cultivates both with success. 
 
 His ideas are analogous to those of A. Gautier, of 
 Chevreul, and of Claude Bernard himself. He thinks, 
 with these masters, that the mystery of life is not to be 
 found in the nature of the forces that it brings into 
 play, but in the direction that it gives them. All these 
 thinkers are struck by the order and the direction 
 impressed upon the phenomena which take place 
 in the living being, by their interconnection, by their 
 apparent adaptation to an end, by the kind of im- 
 pression that they give of a plan which is being 
 carried out. All these reflections lead Reinke to 
 attach great weight to the idea of a "directing 
 force." 
 
 The physico-chemical energies are no doubt the 
 only ones which are manifested in the organized 
 being, but they are directed as a blind man is by his 
 
 1 Reinke, Die Welt als That; Berlin, 1899.
 
 VITALISM. 33 
 
 guide. It seems as if a double accompanies them like 
 a shadow. This intelligent guide of blind, material 
 force is what Reinke calls a dominant Nothing 
 could be more like the bias and the archeus of Van 
 HelmonL Material energies would thus be paired 
 off with their bias, their dominants, in the living 
 organisms. In them there would therefore be two cate- 
 gories of force : " material forces," or rather, material 
 energies obeying the laws of universal energetics ; 
 and in the second place, intelligent " spiritual forces," 
 the dominants. When the sculptor is working his 
 marble, in every blow which elicits a spark there is 
 something more than the strong force of the hammer. 
 There is thought, the volition of the artist, which is 
 realizing a plan. In a machine there is more than 
 machinery. Behind the wheels is the object which 
 the author had in view when he adjusted them for a 
 determined end. The energies spent in action are 
 regulated by the adjustment that is to say, by the 
 dominants due to the intellect of the constructor. 
 
 Thus it is in the living machine. The dominants 
 in this case are the guardians of the plan, the agents 
 of the aim in view. Some regulate the functional 
 activity of the living body, and some regulate its 
 development and its construction. Such is the second 
 form, the philosophical form, extreme and teleological, 
 of contemporary neo-vitalism.
 
 CHAPTER IV. 
 
 THE MONISTIC THEORY. 
 
 Physico-chemical Theory of Life. latro-mechanism. Des- 
 cartes, Borelli. latro-chemistry. Sylvius le Boe. The 
 Physico-chemical Theory of Life. Matter and Energy. 
 Heterogeneity is merely the result of the arrangement or 
 combination of homogeneous bodies. Reservation relative 
 to the world of thought. The Kinetic Theory. 
 
 THE unicist or monistic doctrine gives us a third way 
 of conceiving the functional activity of the living 
 being, by levelling and blending its three forms of 
 activity spiritual, vital, and material. It was 
 expressed in the seventeenth and eighteenth centuries 
 in "iatro-mechanism " and " iatro-chemistry," concep- 
 tions to which have more recently succeeded the 
 physico-chemical doctrine of life, and finally "current 
 materialism." 
 
 Materialism is not only a biological interpretation ; 
 it is a universal interpretation applicable to the whole 
 of nature, because it is based on a determinate con- 
 ception of matter. Here we find ourselves confronted 
 by the eternal enigma discussed by philosophers 
 relative to this fundamental problem of force and 
 matter. We know what answers were given to 
 the problem by the Ionic philosophers Thales, 
 Democritus, Heraclitus, and Anaxagoras, who dis- 
 carded the agency of every spiritual power external 
 34
 
 THE MONISTIC THEORY. 35 
 
 to matter. The explanation of the world, the 
 explanation of life, were reduced to the play of 
 physical or mechanical forces. Epicurus, a little later, 
 maintained that the knowledge of matter and its 
 different forms accounts for all phenomena, and there- 
 fore for those of life. 
 
 Descartes, sharply separating the metaphysical 
 world that is to say, the soul defined by its at- 
 tribute, thought from the physical or material world 
 characterized by extension, practically came to the 
 same conclusions as the materialists of antiquity. To 
 him, as to them, the living body was a mere machine. 
 
 latro-meclianism. Descartes. Borelli. This, then, is 
 the theory of the iatro-mechanicians, of which we may 
 consider Descartes the founder, instead of the Greek 
 philosophers. These ideas held their own for two 
 centuries, and were productive of such fruitful results 
 in the hands of Borelli, Pitcairn, Hales, Bernoulli, and 
 Boerhaave, as to justify the jest of Bacon that " the 
 philosophy of Epicurus had done less harm to science 
 than that of Plato." The iatro-mechanic school ten- 
 aciously held its own until Bichat came upon the scene. 
 
 latro-cliemistry. Sylvius le Boe. It was from a 
 reaction against their exaggerations that Stahl 
 created animism, and the Montpellier school created 
 vitalism. We gather some idea of the extravagant 
 character of their explanations by reading Boerhaave. 
 To this celebrated doctor the muscles were springs, 
 the heart \vas a pump, the kidneys a sieve, and the 
 secretions of the glandular juices were produced by 
 pressure ; the heat of the body was the result of the 
 friction of the globules of blood against the walls of 
 the blood-vessels ; it was greater in the lungs because 
 the vessels of the lungs were supposed to be narrower
 
 36 LIFE AND DEATH. 
 
 than those of other organs. The inadequacy of these 
 explanations suggested the idea of completing them 
 by the aid of the chemistry which was then springing 
 into being. This chemistry, rudimentary as it was, 
 longed for a share in the government of living bodies 
 and in the explanation of their phenomena. Dis- 
 tillations, fermentations, and effervescences are now 
 seen to play their role, a role which was premature 
 and carried to excess. latro-chemistry from the 
 general point of view is only an aspect of iatro- 
 mechanics; but it is also an auxiliary. Sylvius le Boe 
 and Willis were its most eminent representatives. 
 This theory remained in the background until 
 chemistry made its great advance that is to say, in 
 the days of Lavoisier. After that, its importance has 
 gradually increased, particularly in the present day. 
 Nowadays, the general tendency is to regard the 
 organic functional activity, or even morphogeny f.e., 
 whatever there is that is most peculiar to and char- 
 acteristic of living beings as a consequence of the 
 chemical composition of their substance. This is a 
 point of capital importance, and to it we must recur. 
 
 The Physico-chemical Theory of Life. Contemporary 
 biological schools have made many efforts to secure 
 themselves from any slips on the philosophical side. 
 They have avoided in most cases the psychological 
 problem ; they have deliberately refrained from 
 penetrating into the world of the soul. Hence, the 
 pliysico-chemical theory of life has been built up free 
 from spiritualistic difficulties and objections. But 
 this prudence did not exclude the tendency. And 
 there is no doubt, as Armand Gautier said, that real 
 science can affirm nothing, but it also can deny 
 nothing outside observable facts ; 'y and again, that
 
 THE MONISTIC THEORY. 37 
 
 "only a science progressing backwards can venture to 
 assert that matter alone exists, and that its laws alone 
 govern the world." It is none the less true that by 
 establishing the continuity between inert matter and 
 living matter, we thereby render probable the con- 
 tinuity between the \vorld of life and the world of 
 thought 
 
 flatter and Energy. Besides, and without any 
 wish to enter into this burning controversy, it is 
 only too evident that there is no agreement as to the 
 terms that are used, and in particular as to " matter " 
 and "laws of matter." It is not necessary to repeat 
 that the geometrical mould in which Descartes cast 
 his philosophy has long since been broken. The 
 celebrated philosopher, in defining matter by one 
 attribute extension, does not enable us to grasp its 
 activity, an activity revealed by all natural facts ; and 
 in defining the soul by thought alone, prevents us 
 from seeking in it the principle of this material activity. 
 This purely passive matter, consisting of extension 
 alone, this bare matter was to Leibniz a pure concept. 
 A philosopher of our own time, M. Magy, has called it 
 a sensorial illusion. The bodies of nature exhibit to 
 us matter clad with energy, formed by the indissoluble 
 union of extension with an inseparable dynamical 
 principle. The Stoics declared that matter is mobile 
 and not immobile, active and not inert Leibniz also 
 had this in his mind when he associated it indissolubly 
 with an active principle, an "entelechy." Others have 
 said that matter is " an assemblage of forces," or with 
 P. Boscovitch, " a system of indivisible points without 
 extension, centres of force, in fact" Space would be 
 the geometrical locus of these points. 
 
 In this conception the materialistic school finds the
 
 38 LIFE AND DEATH. 
 
 explanation of all phenomenality. Physical properties, 
 vital phenomena, psychical facts, all have their founda- 
 tion in this immanent activity. Material activity is 
 a minimum of soul or thought which, by continuous 
 gradation and progressive complexity, without solution 
 of continuity, without an abrupt transition from the 
 homogeneous to the heterogeneous, rises through the 
 series of living beings to the dignity of the human 
 soul. The observation ot the transitions, an imperfect 
 tracing of the geometrical method of limits, thus 
 enables us to pass from material to vital, and from 
 thence to psychical activity. 
 
 Apparent Heterogeneity is the Result of the Arrange- 
 ment or the Combination of Homogeneous Bodies. In 
 this system, material energy, life, soul would only be 
 more and more complex combinations of the con- 
 substantial activity with material atoms. Life appears 
 distinct from physical force, and thought from life, 
 because the analysis has not yet advanced far enough. 
 Thus, glass would appear to the ancient Chaldeans 
 distinct from the sand and salt of which they made it. 
 In the same way, again, water, to modern eyes, is 
 distinct from its constituents, oxygen and hydrogen. 
 The whole difficulty is that of explaining what this 
 "arrangement" of the elements can introduce that 
 is new in the aspect of the compound. We must 
 know what novelty and apparent homogeneity the 
 variety of the combinations, which are only special 
 arrangements of the elementary parts, may produce in 
 the phenomena. But we do not know, and it is this 
 ignorance which leads us to consider them as hetero- 
 geneous, irreducible, and distinct in principle. The 
 vital phenomenon, the complexus of physico-chemical 
 facts, thus appears* to us essentially different from
 
 THE MONISTIC THEORY. 39 
 
 those facts, and that is why we picture to ourselves 
 " dominants " and " directing forces " more or less 
 analogous to the sidereal guiding principle of Kepler, 
 which, before the discover}* of universal attraction, 
 regulated the harmony of the movements of the 
 planets. 
 
 A Reservation relative to tJie Psycliical Order. 
 The scientific mind has shown in every age a real 
 predilection towards the mechanical or materialistic 
 theory. Contemporary scientists as a whole have 
 accepted it in so far as it blends the vital and the 
 physical orders. Objections and contradictions are 
 only offered in the realm of psychology. A. Gautier, 
 for example, has contested with infinite originality 
 and vigour the claims of the materialists who would 
 reduce the phenomenon of thought to a material 
 phenomenon. The most general characteristic of 
 material phenomenality is as we shall later see 
 that it may be considered as a mutation of energy 
 fc, it obeys the laws of energetics. Now thought, 
 says A. Gautier, is not a form of material energy. 
 Thought, comparison, volition, are not acts of material 
 phenomenality; they are states. They are realities; 
 they have no mass ; they have no physical existence. 
 They respond to adjustments, arrangements, and 
 concerted groupings of material manifestations of 
 chemical molecules. They escape the laws of 
 energetics. 
 
 Kinetic Tlteory. We shall lay aside for a moment 
 this serious problem relative to the limits of the world 
 of conscious thought and of the world of life. It is on 
 the other side, on the frontiers of living and inani- 
 mate nature, that the mechanical view triumphs. It 
 has furnished a universal conception agreeing with 
 
 4
 
 40 LIFE AND DEATH. 
 
 phenomena of every kind viz., the kinetic theory, 
 which ascribes everything in nature to the movements 
 of particles, molecules, or atoms. 
 
 The living and the physical orders are here reduced 
 to one unique order, because all the phenomena of the 
 sensible universe are themselves reduced to one and 
 the same mechanics, and are represented by means of 
 the atom and of motion. This conception of the 
 world, which was that of the philosophers of the Ionic 
 school in the remotest antiquity, which was modified 
 later by Descartes and Leibniz, has passed into 
 modern science under the name of the kinetic theory. 
 The mechanics of atoms ponderable or imponderable, 
 would contain the explanation of all phenomenality. 
 If it were a question of physical properties or" vital 
 manifestations, the objective world in final analysis 
 would offer us nothing but motion. Every pheno- 
 menon would be expressed by an atomistic integral, 
 and that is the inner reason of the majestic unity 
 which reigns in modern physics. The forces which 
 are brought into play by Life are no longer to 
 be distinguished in this ultimate analysis from 
 other natural forces. All arc blended in molecular 
 mechanics. 
 
 The philosophical value of this theory is undeniable. 
 It has exercised on physical science an influence which 
 is justified by the discoveries which it has suggested. 
 But to biology, on the other hand, it has lent no aid. 
 It is precisely because it descends too deeply into 
 things, and analyzes them to the uttermost, that it 
 ceases to throw any light upon them. The distance 
 between the hypothetical atom and the apparent and 
 concrete fact is too great for the one to be able to 
 throw light on the other The vital phenomenon
 
 THE MONISTIC THEORY. 4! 
 
 vanishes with its individual aspect; its features can 
 no longer be distinguished. 
 
 Besides, a whole school of contemporary physicists 
 (Ostwald of Leipzig, Mach of Vienna) is beginning to 
 cast some doubt on the utility of the kinetic hypothesis 
 in the future of physics itself, and is inclined to pro- 
 pose to substitute for it the theory of energetics. We 
 shall see, in every case, that this other conception, as 
 universal as the kinetic theory, tlie theory of Energy, 
 causes a vivid light to penetrate into the depths of the 
 most difficult problems in physiology. 
 
 Such are, with their successive transformations, the 
 three principal theories, the three great currents 
 between which biology has been tossed to and fro. 
 They are sufficiently indicative of the state of positive 
 science in each age, but one is astonished that they 
 are not more so; and this is due to the fact that these 
 conceptions are too general. They soar too high above 
 reality. More characteristic in this respect will be 
 particular theories of the principal manifestations of 
 living matter, of its perpetuity by generation, of the 
 development by which it acquires its individual form, 
 on heredity. It is here that it is of importance to 
 grasp the progressive march of science that is to say, 
 the design and the plan of the building which is being 
 erected, " blindly, so to speak," by the efforts of an 
 army of workers, an army becoming more numerous 
 day by day.
 
 CHAPTER V. 
 
 THE EMANCIPATION OF SCIENTIFIC RESEARCH 
 FROM THE YOKE OF PHILOSOPHICAL THEORIES. 
 
 The excessive use of Hypothetical Agents in Physiological 
 Explanations I. Vital Phenomena in Ftdly-constituted 
 Organisms Provisory Exclusion of the Morphogenic 
 idea The Realm of the Morphogenic Idea as the 
 Sanctuary of Vital Force 2. The Physiological Domain 
 properly so called Harmony and Connection of Pheno- 
 mena Directive Forces Claude Bernard's Work 
 Exclusion of Vital Force, of Final Cause, of the " Caprice " 
 of Living Nature Determinism The Comparative 
 Method Generality of Vital Phenomena Views of 
 Pasteur. 
 
 THE theories whose history we have just sketched 
 in broad outline long dominated science and exer- 
 cised their influence on its progress. 
 
 This domination has ceased to exist. Physiology- 
 has emancipated itself from their sway, and this, 
 perhaps, is the most important revolution in the whole 
 history of biology. Animism, vitalism, materialism, 
 have ceased to exercise their tyranny on scientific 
 research. These conceptions have passed from the 
 laboratory to the study; from being physiological, 
 they have become philosophical. 
 
 This result is the work of the physiologists of sixty 
 
 years ago. It is also the consequence of the general 
 
 march of science and of the progress of the scientific 
 
 spirit, which shows a more and more marked tendency 
 
 42
 
 EMANCIPATION OF SCIENTIFIC RESEARCH. 43 
 
 to separate completely the domain of facts from the 
 domain of hypotheses. 
 
 Excessive Use of HypotJietical Agents in Physio- 
 logical Explanations. It may be said that in the 
 early part of the nineteenth century, in spite of the 
 efforts of a few real experimenters from Harvey to 
 Spallanzani, Hales, Laplace, Lavoisier, and Magendie, 
 the science of the phenomena of life had not followed 
 the progress of the other natural sciences. It remained 
 in the fog of scholasticism. Hypotheses were mingled 
 with facts, and imaginary agents carried out real acts, 
 in inexpressible confusion. The soul (animism), the 
 vital force (vitalism), and the final cause (finalism, 
 teleology) served to explain everything. 
 
 In truth, it was also at this time that physical 
 agents, electric and magnetic fluids, or, again, chemical 
 affinity, played an analogous part in the science of 
 inanimate nature. But there was at least this 
 difference in favour of physicists and chemists, that 
 when they had attributed some new property or 
 aptitude to their hypothetical agents they respected 
 what they attributed. The physiological physicians 
 respected no law, they were subject to no restraint. 
 Their vital force was capricious; its spontaneity made 
 anticipation impossible; it acted arbitrarily in the 
 healthy body; it acted more arbitrarily still in the 
 diseased body. All the subtlety of medical genius 
 was called into play to divine the fantastic behaviour 
 of the spirit of disease. If we speak here of physio- 
 logists and doctors alone and do not quote biologists, 
 it is because the latter had not yet made their 
 appearance as authorities ; their science had remained 
 purely descriptive, and they had not yet begun to 
 explain phenomena.
 
 44 LIFE AND DEATH. 
 
 Such was the state of things during the first years 
 of the nineteenth century. It lasted, thanks to the 
 founders of contemporary physiology Claude Bernard 
 in France, and Briicke, Dubois-Reymond, Helmholtz, 
 and Ludwig in Germany until a separation took 
 place between biological research and philosophical 
 theories. This delimitation operated in physiology 
 properly so called i.e. in a branch of the biological 
 domain in which as yet joint tenancy had been the 
 rule. An important revolution fixed the respective 
 divisions of experimental science and philosophical 
 interpretation. It was understood that the one ends 
 where the other begins, that the one follows the other, 
 that one may not cross the other's path. There is 
 between them only one doubtful region about which 
 there is dispute, and this uncertain frontier is con- 
 stantly being shifted and science daily gains what 
 philosophy loses. 
 
 i. VITAL PHENOMENA IN CONSTITUTED 
 ORGANISMS. 
 
 A displacement of this kind had taken place at the 
 time of which we speak. It was agreed, that as far as 
 concerns the phenomena which take place in a con- 
 structed and constituted living organism, it would no 
 longer be permissible to allow to intervene in their 
 explanation forces or energies other than those 
 which are brought into play in inanimate nature. 
 Just as when explaining the working of a clock, 
 the physicist will not invoke the volition or the art 
 of the maker, or the design that he had in view, but 
 only the connection of causes and effects which he 
 has utilized ; so, for the living machine, whether the
 
 EMANCIPATION OF SCIENTIFIC RESEARCH. 45 
 
 most complex, such as the human body, or the most 
 elementary, such as the cell, we may not invoke a 
 final cause, a vital force, external to that organism 
 and acting on it from without, but only the con- 
 nections and the fluctuations of effects which are the 
 sole actual and efficient causes. In other words 
 Ludwig, and Claude Bernard in particular, expelled 
 from the domain of active phenomenality the three 
 chimeras Vital Force, Final Cause, and the " Caprice '' 
 of Living Nature. 
 
 But the living being is not only a completely con- 
 structed and completely constituted organism. It is not 
 a finished clock. It is a clock which is making itself, 
 a mechanism which is constructing and perpetuating 
 itself. Nothing of the kind is known to us in inani- 
 mate nature. Physiology has found in what is 
 called morphogeny its temporary limit It is beyond 
 this limit, it is in the study of phenomena by which 
 the organism is constructed and perpetuated, it is in 
 the region of the functions of generation and develop- 
 ment, that philosophical doctrines expand and flourish. 
 This is the present frontier of these two powers, 
 philosophy and science. We shall presently delimit 
 them more precisely. W. Kiihne, a well-known 
 scientist whose death is deplored, not in Germany 
 alone, amused himself by studying the division of 
 biological doctrines among the members of learned 
 societies and in the world of academies. He 
 summed up this kind of statistical inquiry by 
 saying in 1898 at the Cambridge Congress, that 
 physiologists were nearly all advocates of the physico- 
 chemical doctrine of life, and that the majority of 
 naturalists were advocates of vital force, and of the 
 theory of final causes.
 
 46 LIFE AND DEATH. 
 
 Domain of the Morphogenic Idea as the Last Sanc- 
 ttiary of Vital Force. We see the reason for this. 
 Physiology, in fact, has taken up its position in 
 the explanation of the functional activity of the 
 constituted organism i.e., on a ground where 
 intervene, as we shall show further on, no energies 
 and no matter other than universal energies and 
 matter. Naturalists, on the other hand, have more 
 especially considered and from the descriptive point 
 of view alone, at least up to the times of Lamarck 
 and Darwin the functions, the generation, the 
 development and the evolution of species. Now 
 these functions are most refractory and inaccessible 
 to physico-chemical explanations. So, when the 
 time came to give an account of what they had done, 
 the zoologists had substituted for executive agents 
 nothing but vital force under its different names. 
 To Aristotle it is the vital force itself which, as soon 
 as it is introduced into the body of the child, moulds 
 its flesh and fashions it in the human form. Con- 
 temporary naturalists, the Americans C. O. Whitman 
 and C. Philpotts, for example, take the same line of 
 argument. Others, such as Blumenbach and Necdham, 
 in the eighteenth century, invoked the same division 
 under another name, that of the nisus formativns. 
 Finally, others play with words ; they talk of heredity, 
 of adaptation, of atavism, as if these were real, active, 
 and efficient beings; while they are only appella- 
 tions, names applied to collections of facts. 
 
 This region was therefore eminently favourable 
 to the rapid increase of hypotheses, and so they 
 abounded. There were the theories of Buffon, of 
 Lamarck, of Darwin, of Herbert Spencer, of E. 
 Haeckel, of His, of Weismann, of De Vries, and
 
 EMANCIPATION OF SCIENTIFIC RESEARCH. 47 
 
 of \V. Roux. Each biologist of any mark had his own, 
 and the list is endless. But here already this domain 
 of theoretical speculation is checked on various sides 
 by experiment J. Loeb, a pure physiologist, has 
 recently given his researches a direction in which 
 zoology believes may be found the explanation of the 
 mysterious part played by the male element in 
 fecundation. On the other hand, the first experi- 
 ment of the artificial division of the living cell 
 (merotomy)i with its light upon the part played by 
 the nucleus in the preservation and regeneration of 
 the living form, is also the work of a physiological 
 experimenter. It dates back to 1852, and is due to 
 Augustus Waller. This experiment was made on the 
 sensitive nervous cell of the spinal ganglions and on 
 the motor cell of the anterior corn u a of the spinal 
 cord. The effects were correctly interpreted twelve 
 or fifteen years later. All that zoologists have done 
 is to repeat, perhaps unconsciously, this celebrated 
 experiment and to confirm the result. 
 
 Thus we see that the attack upon the vitalist 
 sanctuary has commenced. But it would be a grave 
 mistake to suppose that final cause and vital force are 
 on the point of being dislodged from their entrench- 
 ments. Philosophical speculation has an ample field 
 before it. Its frontiers may recede. For a long time 
 yet there will be room for a more or less modernized 
 vitalism. 
 
 2. THE PHYSIOLOGICAL DOMAIN PROPERLY so 
 
 CALLED. 
 
 Vitalism is even found installed in the region of 
 physiology, although for the moment this science 
 limits its ambition to the consideration of the com-
 
 48 LIFE AND DEATH. 
 
 pletely constructed organized being, perfected in its 
 form. The explanation of the working of this con- 
 stituted machine cannot be complete until we take 
 into account the harmony and the adjustment of its 
 parts. 
 
 Harmony and Connection of Parts : Directive Forces. 
 These constituent parts are the cells. We know 
 that the progress of anatomy has resulted in the 
 cellular doctrine i.e., in the two-fold affirmation 
 that the most complicated organism is composed of 
 microscopic elements, the cells, all similar, true 
 stones of the living building, and that it derives its 
 origin from a single cell, egg, or spore, the sexual cell, 
 or cell of germination. The phenomena of life, looked 
 at from the point of view of the formed individual, 
 are therefore harmonized in space ; just as, regarded 
 from the point of view of the individual in formation 
 and in the species, they are connected in time. This 
 harmony and this connection are in the eyes of the 
 majority of men of science the most characteristic pro- 
 perties of the living being. This is the domain of vital 
 specificity, of the directive forces of Claude Bernard and 
 A. Gautier, and of the dominants of Reinke. It is not 
 certain, however, that this order of facts is more 
 specific than the other. Generation and development 
 have been considered by many physiologists, and 
 quite recently by Le Dantec, as simple aspects or 
 modalities of nutrition or assimilation, the common 
 and fundamental property of every living cell. 
 
 The Work of Claude Bernard. Exclusion of Vital 
 Force, of Vital Cause, oj the " Caprice" of Living Nature. 
 It is not, however, a slight advance or inconsider- 
 able advantage to have eliminated vitalistic hypotheses 
 from almost the whole domain of present-day physi-
 
 ENfAKCIPATION OF SCIENTIFIC RESEARCH. 49 
 
 ology, and to have them, as it were, thrown back into 
 its hinterland. This is the work of the scientific men 
 of the first half of the nineteenth century, and parti- 
 cularly of Claude Bernard, who has thereby won 
 the name of the founder or lawgiver of physiology. 
 They found in the old medical school an obstinate 
 adversary glorying in its sterile traditions. In vain 
 was it proved that vital force cannot be an efficient 
 cause; that it was a creation of the brain, an insub- 
 stantial phantom introduced into the anatomical 
 marionette and moving it by strings at the will of 
 any one its adepts having only to confer upon it a 
 new kind of activity to account for the new act All 
 that had been shown with the utmost clearness by 
 Bonnet of Geneva, and by many others. It had also 
 been said that the teleological explanation is equally 
 futile, since it assigns to the present, which exists, an 
 inaccessible, and evidently ultimately inadequate cause, 
 which does not yet exist These objections were in 
 vain. 
 
 Determinism. And so it was not by theoretical 
 arguments that the celebrated physiologist dealt with 
 his adversaries, but by a kind of lesson on things. In 
 fact he was continually showing by examples that 
 vitalism and the theory of final causes were idle errors 
 which led astray experimental investigation ; that 
 they had prevented the progress of research and the 
 discovery of the truth in every case and on every 
 point in which they had been invoked. He laid down 
 the principle of biological determinism, which is nothing 
 but the negation of the "caprice" of living nature. 
 This postulate, so evident that there was no need to 
 enunciate it in the physical sciences, had to be shouted 
 from the housetops for the benefit of supporters of
 
 50 LIFE AND DEATH. 
 
 vital spontaneity. It is the statement that, under 
 determined circumstances materially identical, the 
 same vital phenomena will be identically reproduced. 
 Comparative Method. Claude Bernard completed 
 this critical work by laying down the laws of experi- 
 ment on living beings. He commended as the rational 
 method of research the comparative method. This 
 should be, and is in fact, the daily instrument of all 
 those who work in physiology. It compels the 
 investigator in every research bearing on organized 
 beings to institute a series of tests, such that the 
 conditions which are unknown and impossible to 
 know may be regarded as identical from one test to 
 another ; and when we are certain that a single 
 condition is variable, it compels him to discover the 
 character of the condition we are dealing with, and 
 to learn to appreciate, and to measure its influence. 
 It is safe to say that the errors which are daily 
 committed in biological work have their cause in 
 some infraction of this golden rule. In physical 
 science the obligation to follow the comparative 
 method is much less felt. In most cases the witness 
 test 1 is useless. In physiology the witness test is 
 indispensable. 
 
 1 In an article on the experimental method recently published 
 in the Dictionnaire de Physiologic, M. Ch. Richet writes as 
 follows: "We must therefore never cease to carry out com- 
 parative experiments. I do not hesitate to say that this 
 comparison is the basis of the experimental method." It is in 
 fact what was taught by Claude Bernard in maxim and by 
 example. It is no exaggeration to assert that nine-tenths of the 
 errors which take place in research work are imputable to some 
 breach of this method. When an investigator makes a mistake, 
 save in the case of material error, it is almost certainly due to the 
 fact that he has neglected to carry out one of the comparative
 
 EMANCIPATION OF SCIENTIFIC RESEARCH. 51 
 
 Generality of Vital Phenomena. If we add that 
 Claude Bernard opposed the narrow opinion, so dear 
 to early medicine, which limited the consideration of 
 vitality to man, and the contrary notion of the essential 
 generality of the phenomena of life from man to the 
 animal, and from the animal to the plant, we shall 
 have given very briefly an idea of the kind of revolu- 
 tion which was accomplished about the year 1864, the 
 date of the appearance of the celebrated C Introduction 
 a la medecine experitnentale. 
 
 The ideas we have just recalled seem to be as 
 evident as they are simple. These principles appear 
 so well founded that in a measure they form an in- 
 tegral part of contemporary mentality. What scientist 
 would nowadays deliberately venture to explain some 
 biological fact by the intervention of the evidently 
 inadequate vital force or final cause? And who, to 
 
 tests required in the problem before him. The following is 
 an instance which happened since the above pages were 
 written : Several years ago a chemist announced the exist- 
 ence in the blood serum of a ferment, lipase, capable of 
 saponifying fats that is to say, of extracting from them the fatty 
 acid. From this he deduced many consequences relative to the 
 mechanism of fermentations. But on the other hand, it has 
 been since shown (April 1902) that this lipase of the serum 
 does not exist How did the error arise? The author in 
 question bad mixed normally obtained serum with oil, and he 
 had noted the acidification of the mixture ; he assured himself 
 of the fact by adding carbonate of soda. He saw the alkalinity 
 of the mixture, serum + oil + carbonate of soda, diminish, and he 
 drew the conclusion that the acid came from the saponified oil. 
 He did not make the comparative test, serum + carbonate of 
 soda. If he had done so, he would have ascertained that it also 
 succeeded, and that therefore as the acid did not come from 
 the saponification of the oil, since there was none, its production 
 could not prove the existence of a lipase.
 
 52 LIFE AND DEATH. 
 
 account for the apparent inconsistency of the result, 
 would bring forward the " caprice " of living nature ? 
 And who again would openly dispute the utility of 
 the comparative method ? 
 
 What the physiologists of to-day, according to 
 Claude Bernard, would no longer do, their pre- 
 decessors would do, and not the least important of 
 them. Longet, for example, at a full meeting of the 
 Academic, apropos of recurrent sensibility, and Colin 
 (of Alfort), communicating his statistical results on 
 the temperature of two hearts, accepted more or 
 less explicitly the indetermination of vital facts. And 
 why confine our remarks to our predecessors? The 
 scientists of to-day are much the same. So here 
 again we see the reappearance of the phantom of 
 the final cause in so-called scientific explanations. 
 One fact is accounted for by the necessity of the 
 self-defence of the organism ; another by the necessity 
 to a warm blooded animal of keeping its temperature 
 constant. Le Dantec has recently reproached zoo- 
 logists for giving as an explanation of fecundation 
 the advantage that an animal enjoys in having a 
 double line of ancestors. We might as well say, as 
 L. Errera has pointed out, that the inundations of the 
 Nile occur in order to bring fertility to Egypt. 
 
 We must not therefore depreciate the marvellous 
 work which has emancipated modern physiology from 
 the tutelage of early theories. The witnesses of this 
 revolution appreciated its importance. One of them 
 remarked as follows, on the appearance of f Introduc- 
 tion a la mededne experimental, which contained, 
 however, only a portion of the theory : " Nothing 
 more luminous, more complete, or more profound, has 
 ever been written upon the true principles of an art so
 
 EMANCIPATION OF SCIENTIFIC RESEARCH. 53 
 
 difficult as that of experiment This book is scarcely 
 known because it is on a level to which few people 
 nowadays attain. The influence it will have on medical 
 science, on its progress, and on its very language, 
 will be enormous. I cannot now prove my assertion, 
 but the reading of this book will leave so strong an 
 impression that I cannot help thinking that a new 
 spirit will at once inspire these splendid researches." 
 This was said by Pasteur in 1866. That is what he 
 thought of the work of his senior and his rival, at the 
 moment when he himself was about to inspire those 
 " splendid researches " with the movement of reform, 
 the importance and the consequences of which have 
 no equivalent in the history of science. By their 
 discoveries and their teaching, by their examples and 
 their principles, Claude Bernard and Pasteur have 
 succeeded in emancipating a portion of the domain of 
 vital facts from the direct intervention of hypothetical 
 agents and first causes. They were compelled, however, 
 to leave to philosophical speculation, to directing 
 forces, to animism, to vitalism, an immense provisory 
 field, the field which corresponds to the functions of 
 generation and of development, to the life of the 
 species and to its variations. Here we find them 
 again in various disguises
 
 BOOK II. 
 
 THE DOCTRINE OF ENERGY AND THE LIVING 
 WORLD. 
 
 Summary: General Ideas of Life. Elementary Life. Chapter 
 I. Energy in General. Chapter II. Energy in Biology. 
 Chapter III. Alimentary Energetics. 
 
 GENERAL IDEAS OF LIFE. ELEMENTARY LIFE. 
 
 Life is the Sinn-total of the Phenomena Common 
 to all Living Beings. Elementary Life. Living 
 beings differ more in form and configuration than 
 in their manner of being. They are distinguished 
 more by their anatomy than by their physiology. 
 There are, in fact, phenomena common to all, from 
 the highest to the lowest. This is because there is 
 that similar or identical foundation, that quid commune 
 which has enabled us to apply to them the common 
 name of " living beings." Claude Bernard gave to 
 this sum-total of manifestations common to all (nutri- 
 tion, reproduction) the name of elementary life. To 
 him general pliysiology was the study of elementary 
 life; the two expressions were equivalent, and they 
 were equivalent to a longer formula which the 
 illustrious biologist has given as a title to one of 
 his most celebrated works The Study of the 
 Phenomena Common to all Living Beings, Animals, 
 54
 
 GENERAL IDEAS OF LIFE. 55 
 
 and Plants. From this point of view each being is 
 distinguished from another being as a given individual 
 and as a particular species ; but all are in some way 
 alike and thus resemble one another: common life, 
 elementary life, the essential phenomena of life; it is 
 life itself > 
 
 The manifestations of life may therefore be regarded 
 from the point of view of what is most general among 
 them. As we go down the scale of anatomical organ- 
 ization, as we pass from apparatus (circulatory', 
 digestive, respiratory, nervous) to the organs which 
 compose them, from the organs to the tissues, and 
 finally from the tissues to the anatomical elements or 
 cells of which they are formed, we approach that 
 common, physiological dynamism which is elementary 
 life, but we do not actually reach it. The cell, the 
 anatomical element, is still a complicated structure. 
 The elementary fact is further from us and lower 
 down. It is in the living matter, in the molecule of 
 this matter, and there we must seek it 
 
 Galen gave in days gone by as the object of 
 researches on life, the knowledge of the use of the 
 different organs of the animal machine; "de usu 
 partium." Later, Bichat assigned to them as their 
 end the determination of the properties of tissues. 
 Modern anatomists and zoologists try to reach the 
 constituent element of these tissues the cell. Their 
 dream is to construct a cellular physiology, a physio- 
 logical cytology ; but we must go further than that. 
 
 1 Le Dantec has objected to this conception of phenomena 
 common to different living beings. He insists that all 
 phenomena which take place in a given living being are 
 proper to him, and differ, however slightly, from those of 
 another individual. The objection is more specious than real 
 
 5
 
 56 LIFE AND DEATH. 
 
 General Physiology, Celhilar Physiology, the 
 Energetics of Living Beings. General physiology, 
 as was taught by Pfliiger and his school, claims 
 to go deeper down than the apparatus, or the 
 organ, or even the cell. As in the case of 
 physics, general physiology endeavours to reach, 
 and really does in many cases reach, as far as 
 the molecule. It is not cellular, it is molecular. 
 Already, in fact, the efforts of modern science have 
 succeeded in penetrating into the most general pheno- 
 mena of the living being those attributable to living 
 matter, or, to speak more clearly, those which result 
 from the play of the universal laws of matter at work 
 in this particular medium which is the organized 
 being. 
 
 Robert Mayer and Helmholtz have the honour of 
 having set physiology in the right road. They 
 founded the energetics of living beings i.e., they 
 regarded the phenomena of life from the point of 
 view of energy, which is the factor of all the pheno- 
 mena of the universe.
 
 CHAPTER I. 
 
 EXERGY IX GEXERAL. 
 
 Origin of the Idea of Energy. The Phenomena of Nature bring 
 into play only two Elements, Matter and Energy. 5 i. 
 Matter.Hl 2. Energy. | 3. Mechankal Energy. | 4. 
 Thermal Energy. f > Chemical Energy. 6. TheTrans- 
 formations of Energy. 7. The Principles of Energetics. 
 The Principle of the Conservation of Energy. 8. Career s 
 Principle. The Degradation of Energy. 
 
 Origin of the Idea of Energy. A new term, namely 
 energy, has been for some years introduced into natural 
 science, and has ever since assumed a more and more 
 important place. It is owing to the English physicists, 
 and especially to the English electrical engineers, that 
 this expression has made its way into technology, an 
 expression which is part and parcel of both languages, 
 and which has the same meaning in both. The idea 
 it expresses is, in fact, of infinite value in industrial 
 applications, and that is why its use has gradually 
 spread and become generalized. But it is not merely 
 a practical idea. It is above all a theoretical idea of 
 capital importance to pure theory. It has become 
 the point of departure of a science, energetics, which, 
 although born but yesterday, already claims to 
 embrace, co-ordinate, and blend within itself all the 
 other sciences of physical and living nature, which die 
 imperfection of our knowledge alone had hitherto 
 kept distinct and apart 
 
 57
 
 58 LIFE AND DEATH. 
 
 On the threshold of this new science we find in- 
 scribed the. principle of the conservation of energy, 
 which has been presented to us by some as Nature's 
 supreme law, and which we may say dominates 
 natural philosophy. Its discovery marked a new era 
 and accomplished a profound revolution in our con- 
 ception of the universe. It is due to a doctor, Robert 
 Mayer, who practised in a little town in Wurtemberg-, 
 and who formulated the new principle in 1842, and 
 afterwards developed its consequences in a series of 
 publications between 1845 and 1851. They remained 
 almost unknown until Helmholtz, in his celebrated 
 memoir on the conservation of force, brought them to 
 light and gave them the importance they deserved. 
 From that time forward the name of the doctor of 
 Heilbronn, until then obscure, has taken its place 
 among the most honoured names in the history of 
 science. 1 
 
 1 Mayer's claim to fame has been disputed. A Scotch physicist, 
 P. G. Tait, has investigated the history of the law of the con- 
 servation of energy, which is the history of the idea of energy. 
 The conception has taken time to penetrate the human mind, 
 but its experimental proof is of recent date. P. G. Tait finds an 
 almost complete expression of the law of the conservation of 
 energy in Newton's third law of motion namely, "the law of the 
 equality of action and reaction," or rather, in the second ex- 
 planation which Newton gave of that law. In fact, it was from 
 this law that Helmholtz deduced it in 1847. He showed that 
 the law of the equality of action and reaction, considered as a 
 law of nature, involved the impossibility of perpetual motion, 
 and the impossibility of perpetual motion is, in another form, the 
 conservation of energy. 
 
 At a meeting of the Academy of Science, at Berlin, 28th 
 March 1878, Du Bois-Reymond violently attacked Tail's con- 
 tention. The honour of having been the first to conceive of the 
 idea of energy and conservation was awarded to Leibniz. 
 Newton had no right to it, for he appealed to divine intervention
 
 ENERGY IN GENERAL. 59 
 
 As for energetics, of which thermodynamics is only 
 a section, it is agreed that even if it cannot forthwith 
 absorb mechanics, astronomy, physics, chemistry, and 
 physiology, and build up that general science which 
 will be in the future the one and only science of 
 nature, it furnishes a preparation for that ideal state, 
 and is a first step in the ascent to definite progress. 
 
 Here I propose to expound these new ideas, in so 
 far as they contain anything universally accessible; 
 and in the second place, I propose to show their 
 application to physiology that is to say, to point out 
 their role and their influence in the phenomena of 
 life. 
 
 Postulate: the Phenomena of Nature bring into 
 play only two Elements, Matter and Energy. If we 
 try to account for the phenomena of the universe, 
 we must admit with most physicists that they 
 bring into play two elements, and two elements only 
 namely, matter and energy. All manifestations are 
 exhibited in one or other of these two forms. This, 
 we may say, is the postulate of experimental science. 
 
 Just as gold, lead, oxygen, the metalloids, and the 
 metals are different kinds of matter, so it has been 
 recognized that sound, light, heat, and generally, the 
 imponderable agents of the days of early physics, are 
 
 to set the planetary system on its path when disturbed by ac- 
 cumulated perturbations. On the other hand, Colding claims to 
 have drawn his knowledge of the law of conservation from 
 d'Alembert's principle. Whatever may be the theoretical 
 foundations of this law, we are here dealing with its experi- 
 mental proof. According to Tail, the proof can no more be 
 attributed to R. Mayer than to Seguin. The real modern 
 authors of the principle of the conservation of energy, who gave 
 an experimental proof of it, are Colding, of Copenhagen, and 
 Joule, of Manchester.
 
 60 LIFE AND DEATH. 
 
 different varieties of energy. The first of these ideas 
 is older and more familiar to us, but it has not for that 
 reason a more certain existence. Energy is objective 
 reality for the same reason that matter is. The 
 latter certainly appears more tangible and more easily 
 grasped by the senses. But, upon reflection, we are 
 assured that the best proof of their existence, in both 
 cases, is given by the law of their conservation that 
 is to say, their persistence in subsisting. 
 
 The objective existence of matter and that of 
 energy will therefore be taken here as a postulate of 
 physical science. Metaphysicians may discuss them. 
 We have but little room for such a discussion. 
 
 i. MATTER. 
 
 It is certainly difficult to give a definition of 
 matter which will satisfy both physicists and meta- 
 physicians. 
 
 Mechanical Explanation of the Universe. Matter is 
 Mass. Physicists have a tendency to consider all 
 natural phenomena from the point of view of mechanics. 
 They believe that there is a mechanical explanation 
 of the universe. They are always on the look out for 
 it, implicitly or explicitly. They endeavour to reduce 
 each category of physical facts to the type of the facts 
 of mechanics. They have made up their minds to see 
 nowhere anything but the play of motion and force. 
 Astronomy is celestial mechanics. Acoustics is the 
 mechanics of the vibratory movements of the air or of 
 sonorous bodies. Physical optics has become the 
 mechanics of the undulations of the ether, after having 
 been the mechanics of emission a wonderful
 
 ENERGY IN GENERAL. 6l 
 
 mechanics which represents exactly all the pheno- 
 mena of light, and furnishes us with a perfect objective 
 image of it Heat, in its turn, has been reduced to a 
 mode of motion, and thermodynamics claims to em- 
 brace all its manifestations. As early as 1812, Sir 
 Humphry Davy wrote as follows: "The immediate 
 cause of heat is motion, and the laws of transmission 
 are precisely the same as those of the transmission 
 of motion." From that time forth, this conception 
 developed into what is really a science. The constitu- 
 tion of gases has been conceived by means of two 
 elements particles, and the motions of these particles, 
 determined in the strictest detail And finally, in spite 
 of the difficulties of the representation of electrical and 
 magnetic phenomena after Ampere and before Maxwell 
 and Hertz, physicists have been able to announce in the 
 second half of the nineteenth century the unity of the 
 physical forces realized in and by mechanics. From 
 that time forth, all phenomena have been conceived 
 as motion or modes of motion, only differing essen- 
 tially one from the other in so far as motions may 
 differ that is to say, in the masses of the moving 
 particles, their velocities, and their trajectories. The 
 external world has appeared essentially homogeneous ; 
 it has fallen a prize to mechanics. Above all, there 
 is heterogeneity in ourselves. It is in the brain, 
 which responds to the nervous influx engendered by 
 the longitudinal vibration of the air, by the specific 
 sensation of sound, which responds to the transverse 
 vibration of the ether by a luminous sensation, and in 
 general to each form of motion by an irreducible 
 specific sensation. 
 
 Forty years have passed since the mechanical ex- 
 planation of the universe reached its definite and
 
 62 LIFE AND DEATH. 
 
 perfect form. It dominates physics under the name 
 of the theory of kinetic energy. The minds of men in 
 our own time are so strongly impregnated with this 
 idea that most scientists of ordinary culture get no 
 glimpse of the world of phenomena but by means of 
 this conception. And yet it is only an hypothesis. 
 But it is so simple, so intuitive, and appears to be so 
 thoroughly verified by experiment, that we have 
 ceased to recognize its arbitrary and unnecessarily 
 contingent character. Many physicists from this 
 standpoint consider the kinetic theory as an im- 
 perishable monument. 
 
 However, as in the case of H. Poincare, the most 
 eminent physicists and mathematicians are not the 
 dupes of this system; and without failing to recognize 
 the immense services which it has rendered to science, 
 they are perfectly well aware that it is only a system, 
 and that there may be other systems. Certain among 
 them, such as Ostwald, Mach, and Duhem, believe 
 that the monument is showing signs of decay, and at 
 present the theory is opposed by another theory 
 namely, the theory of energy. 
 
 The theory of energy is usually considered and pre- 
 sented as a consequence of the kinetic theory; but it 
 is perfectly independent of it, and it is, in fact, without 
 relying on the kinetic theory, without assuming the 
 unity of physical forces, which are combined in mole- 
 cular mechanics, that we shall expound the general 
 system. 
 
 This is not the point at issue for the moment. It is 
 not a question of deciding the reality or the merit of 
 this or that mechanical explanation ; it is a question 
 of something more general, because upon it depends 
 the idea of matter. It is a question of knowing if
 
 ENERGY IN GENERAL. 63 
 
 there are any explanations other than mechanical 
 The illustrious English physicist, Lord Kelvin, does 
 not seem willing to admit this. "I am never satisfied," 
 he said, in his Molecular Mechanics, "until I have 
 made a mechanical model of the object If I can 
 make this model, I understand ; if I cannot, I do not 
 understand." 
 
 This tendency of so vigorous a mind to be con- 
 tent only with mechanical explanations, has been 
 that of the majority of scientific men up to the 
 present day, and from it has arisen the scientific idea 
 of matter. 
 
 What is matter, in fact, to the student of mechanics? 
 It is mass. All mechanics is constructed of *"?<* 
 and forces. Laplace said : " The mass of a body is the 
 sum of its material points." To Poisson, mass is the 
 quantity of matter of which a body is composed. 
 Matter is therefore confused with mass. Now, mass 
 is the characteristic of the motion of a body under the 
 action of a given force; it defines obedience or resist- 
 ance to the causes of motion ; it is the mechanical 
 parameter; it is the co-efficient proper to every mobile 
 body; it is the first invariant of which a conception 
 has been established by science. 
 
 In fact, the word matter appears to be used in 
 other senses by physicists, but this is only apparently 
 so. They have but broadened the idea of the 
 mechanicians. They have characterized matter by 
 the whole series of phenomenal manifestations which 
 are proportional to mass, such as weight, volume, 
 chemical properties so that we may say that the 
 notion of matter does not intervene scientifically with 
 a different signification from that of mass. 
 
 Two kinds of Matter. Ponderable and Imponder-
 
 64 LIFE AND DEATH. 
 
 able. In physics we distinguish between two kinds 
 of matter ponderable, obeying the law of universal 
 attraction or weight, and imponderable matter or 
 ether, which we assume to exist and to escape the 
 action of that force. Ether has no weight, or ex- 
 tremely little weight. It is material in so far as it 
 has mass. It is its mass which confers existence on 
 it from the mechanical point of view a logical ex- 
 istence, inferred from the necessity of explaining the 
 propagation of heat, light, or electricity. 
 
 It may be observed that the use of mass really 
 comes to bringing another element, force, to intervene, 
 and we shall see that force is connected with energy ; 
 thus it comes to defining matter indirectly by energy. 
 The two fundamental elements are not therefore 
 irreducible ; on the contrary, they should be one and 
 the same thing. 
 
 Energy is the only Objective Reality. This fusion 
 into one will become more evident still when we 
 examine the different kinds of energy, each of which 
 exactly corresponds to one of the aspects of active 
 matter. Shall we define matter by extension, by the 
 portion of space it occupies, as certain philosophers 
 do? The physicist will answer that space is only 
 known to us by the expenditure of energy necessary 
 to penetrate it (the activity of our different senses). 
 And then what is weight? It is energy of position 
 (universal attraction). And so with the other attri- 
 butes. So that if matter were separated from the 
 energetic phenomena by means of which it is revealed 
 to us weight or energy of position, impenetrability 
 or energy of volume, chemical properties or chemical 
 energies, mass or capacity for kinetic energy the very 
 idea of matter would vanish. And that comes to
 
 ENERGY IN GENERAL. 65 
 
 saying that fundamentally there is only one objective 
 reality, energy. 
 
 Philosophical Point of View. But from the philo- 
 sophical point of view are there objective realities? 
 That is a wider question which throws doubt upon 
 matter itself, and which it is not our place to investi- 
 gate here. A metaphysician may always discuss and 
 deny the existence of the objective world. Jt may be 
 maintained that man knows nothing beyond his 
 sensations, and that he only objectivates them and 
 projects them outside himself by a kind of hereditary 
 illusion. We must avoid taking sides in all these 
 difficulties. Physics for the moment ignores them 
 ije^ postpones their consideration. 
 
 In a first approximation we agree to consider 
 ponderable matter only. Chemistry acquaints us 
 with its different forms. They are the different 
 simple bodies, metalloids, metals, and the compound 
 bodies, mineral or organic. Hence we may say that 
 chemistry is the history of tJu transformations of 
 matter. From the time of Lavoisier this science has 
 followed the transformations of matter, balance in 
 hand, and ascertains that they are accomplished 
 without change of weight. 
 
 Law of the Conservation of Matter. Imagine a 
 system of bodies enclosed in a closed vessel, and the 
 vessel placed in the scale of a balance. All the 
 chemical reactions capable of completely modifying 
 the state of this system have no effect upon the scale 
 of the balance. The total weight is the same before, 
 during, and after. It is precisely this equality of 
 weight which is expressed in all the equations with 
 which treatises on chemistry are filled. 
 
 From a higher point of view we recognize here, in
 
 66 LIFE AND DEATH. 
 
 this law of Lavoisier or of the conservation of weight, 
 the verification of one of the great laws of nature 
 which we extend to every kind of matter, ponderable 
 or not. It is the law of the conservation of matter, 
 or again, of the indestructibility of matter " Nothing 
 is lost, nothing is created, all is transformation." This 
 is exactly what Tait held, this impossibility of creating 
 or destroying matter which at the same time is a 
 proof of its objective existence. This indestructibility 
 of ponderable matter is at the same time the funda- 
 mental basis of chemistry. Chemical analysis could 
 not exist if the chemist were not sure that the contents 
 of his vessel at the end of his operations ought to be 
 quantitatively, that is to say by weight, the same as at 
 the beginning, and during the whole course of the 
 experiment. 1 
 
 2. ENERGY. 
 
 The Idea of Energy Derived from the Kinetic 
 Theory. The notion of energy is not less clear than 
 the notion of matter, it is only more novel to our 
 minds. We are led to it by the mechanical conception 
 which now dominates the whole of physics, the kinetic 
 conception, according to which in the sensible universe 
 there are no phenomena but those of motion. Heat, 
 sound, light, with all their manifestations so complex 
 and so varied, may, according to this theory, be 
 explained by motion. But then, if outside the brain 
 and the mind which has consciousness and which 
 perceives, Nature really offers us only motion, it 
 follows that all phenomena are essentially homo- 
 
 1 It must be added that the absolute rigour of this law has 
 been called in question in recent researches. It would only 
 have an approximate value.
 
 ENERGY IN GENERAL. 67 
 
 geneous among one another, and that their apparent 
 heterogeneity is only the result of the intervention of 
 our sensorium. They differ only in so far as move- 
 ments are capable of differing that is to say, in 
 velocity, mass, and trajectory. There is something 
 fundamental which is common to them and this quid 
 commune is energy. Thus the idea of energy may be 
 derived from the kinetic conception, and this is the 
 usual method of exposition. 
 
 This method has the great inconvenience of causing 
 an idea which lays claim to reality to depend upon an 
 hypothesis. And besides that, it gives a view of it 
 which may be false. It makes of the different forms 
 of energy something more than varieties which are 
 equivalent to one another. It makes of them one and 
 tJie same thing. It blends into one the modalities of 
 energy and mechanical energy. For the experimental 
 idea of equivalence, the kinetic theory substitutes the 
 arbitrary idea of the equality, the blending, and the 
 fundamental homogeneity of phenomena. This no 
 doubt is how the founders of energetics, Helmholtz, 
 Clausius, and Lord Kelvin understood things. But a 
 more attentive study and a more scrupulous deter- 
 mination not to go beyond the teaching of experiment 
 should compel us to reform this manner of looking at 
 it And it is Ostwald's merit that, after Hamilton, he 
 insisted on this truth that the various kinds of 
 physical magnitudes furnished by the observation of 
 phenomena are different and characteristic. In par- 
 ticular, we may distinguish among them those which 
 belong to the order of scalar magnitudes and others 
 which are of the order of vector magnitudes, 
 
 TJie Idea of Energy derived from the Connection 
 of Phenomena. The idea of energy is not absolutely
 
 68 LIFE AND DEATH. 
 
 connected with the kinetic theory, and it should not 
 be exposed therefore to the vicissitudes experienced 
 by that theory. It is of a higher order of truth. We 
 can derive it from a less unsafe idea, namely that of 
 the connection of natural phenomena. /To conceive it 
 we must get accustomed to this primordial truth, that 
 there are no plienomena isolated, in time and space. 
 This statement contains the whole point of view of 
 energetics. / 
 
 The physics of early days had only an incomplete 
 view of things, for it considered phenomena in- 
 dependently the one of the other. 
 
 Phenomena for purposes of analysis were classed in 
 separate and distinct compartments: weight, heat, 
 electricity, magnetism, light. Each phenomenon was 
 studied without reference to that it succeeded or that 
 which should follow. Nothing could be more artificial 
 than such a method as this. In fact, there is a 
 sequence in everything, everything is connected up, 
 everything precedes and succeeds in nature in nature 
 there are only series. The isolated fact without 
 antecedent or consequent is a myth. Each 
 phenomenal manifestation is in solidarity with 
 another. It is a metamorphosis of one state of 
 things into another. It is transformation. It implies 
 a state of things anterior to that which we are 
 observing, a phenomenal form which has preceded 
 the form of the present moment. 
 
 Now there exists a link between the anterior state 
 and the succeeding state that is to say, between the 
 new form which is appearing and the preceding form 
 which is disappearing The science of energy shows 
 that something has passed from the first condition to 
 the second, but covering itself as it were with a new
 
 ENERGY IN GENERAL. 69 
 
 garment; in a word, that something active and 
 permanent subsists in the passage from one condition 
 to another, and that what has changed is_qn]y the 
 aspect, the appearance. 
 
 This constanFsomething which is perceived beneath 
 the inconstancy and the variety of forms, and which 
 circulates in a certain manner from the/, antecedent 
 phenomenon to its successor, is energy. J^/j^ - 
 
 But still this is only a very vague" view, and it may 
 seem arbitrary. It may be made more exact by 
 examples borrowed from the different categories of 
 natural phenomena. There are energetic modalities 
 in relation with the different phenomenal modalities. 
 The different orders of phenomena which may be 
 presented mechanical, chemical, thermal, electrical 
 give rise to corresponding forms of energy. 
 
 When to a mechanical phenomenon succeeds a 
 mechanical, thermal, or electrical phenomenon, we 
 say, embracing transformation in its totality, that 
 there has been a transformation of mechanical energy 
 into another form of energy, mechanical, thermal, or 
 electrical, etc. 
 
 This idea becomes more precise if we examine 
 successively each of these cases and the laws which 
 regulate them. 
 
 3. MECHANICAL ENERGY. 
 
 Mechanical energy is the simplest and the oldest 
 known. 
 
 Mechanical Elements: Time, Space, Force, Work. 
 Power. Mechanical phenomena may be considered 
 under two fundamental conditions time and space,
 
 70 LIFE AND DEATH. 
 
 which are, in a measure, logical elements, to which 
 may be joined a third element, itself experimental, 
 having its foundations in our sensations namely, 
 force, work, or power. 
 
 The ideas of force, work, and power, are drawn from 
 the experience man has of his muscular activity. 
 Nevertheless the greatest mathematical minds from 
 from Descartes to Leibniz have been obliged to define 
 and explain them clearly. 
 
 Force. The prototype of force is weight, universal 
 attraction. Experiment shows us that* every body 
 falls as long as no obstacle opposes its fall. This is 
 so universal a property of matter that it serves to 
 define it. The force, weight, is therefore the name 
 given to the cause of the fall of the bodies. 
 
 Force in general is the cause of motion. Hence 
 force exists only in so far as there is motion. There 
 would be no force without action. This is Newton's 
 point of view. It did not prevail, and was not the 
 point of view of his successors. The name of force 
 has been given not only to the cause which produces 
 or modifies motion, but to the cause which resists and 
 prevents it. And then not only have forces in action 
 been considered (dynamics), but forces at rest (statics). 
 Now, to Newton there was no statics. Forces do not 
 continue to exist when they produce no motion ; they 
 are not in equilibrium, they are destroyed. 
 
 The idea of force therefore is a metaphysical idea 
 which contains the idea of cause. But it becomes 
 experimental immediately it is looked upon as resist- 
 ing motion, according to the point of view of Newton's 
 opponents. Its foundations lie in the muscular 
 activity of man. 
 
 Man can support a burden without bending or
 
 ENERGY IN GENERAL. 71 
 
 moving. This burden is a weight that is to say, a 
 mass acted on by the force of weight Man resists 
 this force so as to prevent its effect. If it were not 
 annihilated by man's effort^ this effect would be the 
 motion or the fall of the heavy body. The effort and 
 the force are thus in equilibrium, and the effort is 
 equal and opposite to the force. It gives to the man 
 who exercises it the conscious idea of force. Thus we 
 know of force through effort. Every clear idea that 
 we can have of force springs from the observation of 
 our muscular effort. 
 
 The notion of force is thus an anthropomorphic 
 notion. When an effect is produced in nature outside 
 human intervention, we say that it is by something 
 analogous to what in man is effort, and we give to this 
 something a name which is also analogous, namely 
 force. To give a name to effort and to compare 
 efforts in magnitude, we need not know all about 
 them, nor need we know in what they essentially 
 consist, of what series of physical, chemical, and 
 physiological actions they are the consequence. And 
 so it is with force. It is a resistance to motion or 
 the cause of motion. This cause of motion may be 
 an anterior motion (kinetic force). It may be an 
 anterior physical energy (physical and chemical 
 forces). 
 
 Forces are measured in the C.G.S. system by com- 
 paring them with the unit called the Dyne. 1 In 
 practice they are compared with a much larger unit 
 the gramme, which is the weight, the force acting on 
 a unit of mass of one centimetre of distilled water at 
 a temperature of 4" C. 
 
 1 The dyne is the force which applied to the unit of mass 
 produces a unit of acceleration. 
 
 6
 
 72 LIFE AND DEATH. 
 
 Work. The muscular activity of man may be 
 brought into play in yet another manner. When we 
 employ workmen, as Carnot said in his Essai sur 
 fequilibre et le mouvement, it is not a question of 
 "knowing the burdens that they can carry without 
 moving from their position," but rather the burdens 
 that they can carry from one point to another. For 
 instance, a workman may have to lift the water from 
 the bottom of a well to a given height, and the case is 
 the same for the animals we employ. " This is what 
 we understand by force when we say that the force of 
 a horse is equal to the force of seven men. We do 
 not mean that if seven men were pulling in one 
 direction and the horse in another that there would be 
 equilibrium, but that in a piece of work the horse 
 alone would lift, for example, as much water from the 
 bottom of a well to a given height as the seven men 
 together would do in the same time." * 
 
 Here, then, we have to do with the second form of 
 muscular activity, which is called in mechanics, "work" 
 at least, if in the preceding quotation we attach no 
 particular importance to the words "in the -same 
 time," and retain the employment of muscular activity 
 only "under constant conditions." Mechanical work 
 is compared with the elevation of a certain weight to a 
 certain height. It is measured by the product of the 
 force (understood in the sense in which it was used 
 just now that is to say, as causing or resisting motion) 
 and the displacement due to this motion. The unit is 
 the Kilogrammetre that is to say, the work necessary 
 to lift a weight of one kilogramme to the height of 
 one metre. 
 
 1 These words spoil the statement, for time has nothing to 
 do with it.
 
 ENERGY HI GENERAL, 75 
 
 It will be remarked that the idea of time does not 
 intervene in our estimation of work The notion of 
 work is independent of the ideas of velocity and 
 time. " The greater or less time that we take to do 
 a piece of work is of no more assistance in measur- 
 ing its magnitude than the number of years that 
 a man may have taken to grow rich or to ruin him- 
 self can help to estimate the present amount of his 
 fortune." 
 
 Going back to Carnot's comparison, an employer 
 who employed his workmen only on piece-work, that 
 is to say, who would only care about the amount of 
 work done, and would be indifferent to the time that 
 they took over it, would be at the same point of view 
 as the advocates of the mechanical theory. M. 
 Bouasse, whom we follow here, has remarked that this 
 idea of mechanical work may be traced back to 
 Descartes. His predecessors, and Galileo in par- 
 ticular, had quite a different idea of the way in which 
 mechanical activity should be measured; and so, 
 among the mathematicians of the eighteenth century, 
 Leibniz and, later, John Bernoulli were almost <alone 
 in looking at it from this point of view. 
 
 Energy. Work thus understood is nuchanical 
 energy. It represents the lasting and objective effect 
 of the mechanical activity independent of all the cir- 
 cumstances under which it was carried out. The 
 same work may be done under very different con- 
 ditions of time, velocity, force, and displacement. 
 It is therefore the permanent element in the variety of 
 mechanical aspects. Work, for example, in the 
 collision of bodies when the motion of a body appears 
 to be destroyed on impact with another, reappears as 
 indestructible vis viva. This, then, is exactly what
 
 74 LIFE AND DEATH. 
 
 we call energy; and if we agree to give it this name, 
 we may say that the conservation of energy is 
 invariable throughout all mechanical transforma- 
 tions. 
 
 Distinction between Work and Force, and between 
 Energy and Work. The history of mechanics shows 
 us what trouble has been taken and what efforts have 
 been made to distinguish work (now mechanical 
 energy) from force. 
 
 It is worth while insisting on this distinction. It 
 could be easily shown that force has no objective ex- 
 istence. It has no duration, no permanence. It does 
 not survive its effect, motion. There is no conserva- 
 tion of force. It passes instantly from infinity to 
 zero. It is a vectorial magnitude that is to say, it 
 involves the idea of direction. Work, on the other 
 hand, is the real element; it is a scalar magnitude 
 involving the idea of opposite directions, indicated by 
 the signs + and - . Work and force are hetero- 
 geneous magnitudes. Energy, and this is the only 
 characteristic by which it is distinguished from work, 
 is an absolute magnitude to which we may not even 
 give opposite signs. 
 
 An example may perhaps throw these characteristics 
 into relief namely, the hydraulic press. We have on 
 the platform exactly the work which has been done 
 on the other side. The machine has only made it 
 change its form. On the contrary, the force has been 
 infinitely multiplied. We may, in fact, consider an 
 infinite number of surfaces equal to that of a small 
 piston, placed and orientated at will within the liquid ; 
 each, according to Pascal's principle, will support a 
 pressure equal to that which is exercised. As soon as 
 we cease to support it, this infinity falls at once to zero.
 
 ENERGY IX GENERAL. 75 
 
 Now what real thing could pass instantly from infinity 
 to zero? 
 
 That skilful and very able physiologist, M. Chauveau, 
 has endeavoured to use the same term energy of con- 
 traction for the two phenomena of effort (force) and 
 work. It seems, however, from the point of view of 
 the expenditure imposed on the organism, that these 
 two modes of activity, static contraction (effort), and 
 dynamical contraction (work), may be, in fact, perfectly 
 comparable. But although this manner of conceiving 
 the phenomena may certainly be exact, and may be 
 of great value, the idea of force must none the less 
 remain distinct from that of work. The persistence 
 of the author in violating established custom in this 
 connection has prevented him from enabling mechani- 
 cians and even some physiologists to understand and 
 accept very useful truths. 
 
 Power. The idea of mechanical power differs from 
 those of force and work. The idea of time must 
 intervene. It is not sufficient, in fact, in order to 
 characterize a mechanical operation, to point to the 
 task accomplished. It may be necessary or useful to 
 know how much time it required. This is true, 
 especially when we are concerned with the circum- 
 stances as well as the results of the performance of 
 the work; and this is the case when we wish to 
 compare machines. We say that the machine which 
 does the work in the shortest space of time is 
 the most powerful. The unit of power is the Kilo- 
 gram metre-second that is to say, the power of a 
 machine which does a kilogrammetre in a second. In 
 manufactures we generally employ a unit 75 times 
 greater than this a horse-power. This is the power of 
 a machine which does 75 kilogrammetres a second,
 
 76 LIFE AND DEATH. 
 
 In the electrical industry we measure by kilowatts, 
 which are equivalent to 1.36 horse power, or by a watt, 
 a unit a thousand times smaller. 
 
 Let us add that the power of a machine is not an 
 absolute and permanent characteristic of the machine. 
 It depends on the circumstances under which the 
 work is carried out, and that is why, in particular, we 
 cannot appreciate the power of the human machine in 
 comparison with industrial machines. Experience 
 has shown that the mechanical power of living beings 
 depends upon the nature of the work they are doing. 
 In this connection we may mention some very inter- 
 esting experiments communicated to the Institute, in 
 the year VI., by the celebrated physicist, Coulomb. A 
 man of the average weight of 70 kilogrammes was 
 made to climb the stairs of a house 20 metres high. 
 He ascended at the rate of 14 metres a minute, and 
 he performed this daily task for four effective hours. 
 This work was equivalent to 235,000 kilogrammetres. 
 But if, instead of climbing without a burden, the same 
 man had had to carry a load, the result would have 
 been quite different. Coulomb's workman took up 
 six loads of wood a day to a height of 12 metres 
 in 66 journeys, corresponding to a maximum 
 work of 109,000 instead of 235,000 kilogrammetres. 
 The mechanical power of the human machine 
 thus varied in the two cases in the ratio of 235 
 to 109. 
 
 The Two Aspects of Mechanical Energy : Kinetic 
 and Potential. Energy, or mechanical work, may 
 present itself in two forms kinetic energy, corre- 
 sponding to the mechanical phenomenon which has 
 really taken place, and potential energy, or the energy 
 of reserve.
 
 ENERGY IX GENERAL. 77 
 
 A body which has been raised to a certain 
 height will, if it be let fall, perform work which 
 can be exactly measured in kilogrammetres by the 
 product of its weight into the height it falls. Such 
 work may be utilized in many ways. In this way, 
 for instance, public clocks are worked. Now, as long 
 as the clock-weight is raised and not let go, and 
 as long as it is motionless, the physics of early 
 days would say that there is nothing to discuss ; 
 the phenomenon is the fall ; it is going to take 
 place, but at the present moment there has been 
 no falL 
 
 In energetics we do not reason in this way. \Ve 
 say that the body possesses a capacity far work which 
 will be manifested when the opportunity arises, a 
 storage of energy, a virtual or potential energy, or 
 again, an energy of position, which will be transformed 
 into actual energy or real work as soon as the body 
 falls. 
 
 Let us ask whence this energy arises. It proceeds 
 from the previous operation which has raised the 
 weight from the surface of the soil to the position it 
 occupies. For example, if it is a question of the 
 weights of a public clock, which, by its fall, will develop 
 in 15 days the work that is necessary to turn the 
 wheels, to strike the bell, and to turn the hands, 
 this work ought to bring to our minds the exactly equal 
 and opposite work done by the clockmaker, who has 
 to carry the clock-weight and to lift it up from the 
 ground to its point of departure. The work of the 
 fall is the faithful counterpart of the work of elevation. 
 The phenomenon has therefore in reality two phases. 
 We find in the second exactly what was put into the 
 first, the same quantity of energy />., the same work.
 
 78 LIFE AND DEATH. 
 
 Between these phases comes the intermediary phase 
 of which we say that it is a period of virtual or poten- 
 tial energy. This is a way of remembering in some 
 measure the preceding phenomenon i.e., the work of 
 lifting up, and of indicating the phenomena which will 
 follow i.e., the work of the fall. And thus we connect 
 by our thoughts the present situation with the ante- 
 cedent and with the consequent position, and it is 
 from this consideration of continuity alone that the 
 conception of energy springs that is to say, of some- 
 thing which is conserved and is found to be permanent 
 in the succession of phenomena. This energy of 
 which we lose no trace does not appear to us new 
 when it is manifested. Our imagination eventually 
 materializes the idea of it. We follow it as a real 
 thing, having an objective existence, which is asleep 
 during the latent potential period, and is revealed or 
 manifested later. 
 
 Among other examples, that of the coiled spring 
 which is unwound is particularly suitable for show- 
 ing this fundamental character of the idea of 
 mechanical energy, an idea which is the clearest 
 of all. Machines are only transformers and not 
 creators of mechanical energy. They only change 
 one form into another. 
 
 *"" In the same way, too, a stream of water or the 
 torrent of a mountainous region may be utilized for 
 setting in motion the wheels and the turbines of the 
 factories situated in the valley. Its descent produces 
 the mechanical work which would be a creation ex 
 nihilo if we do not connect the phenomenon with its 
 antecedents. We look on it as a simple restitution, if 
 we think of the origin of this water which has been 
 transported and lifted in some way to its level by the
 
 ENERGY IX GENERAL. 79 
 
 play of natural forces evaporation under the action 
 of the sun, the formation of clouds, transport by winds, 
 etc. And we here again see that a complex energy 
 has been transformed, in its first phenomenal con- 
 dition, into potential energy, and that this potential 
 energy is always expended in the second phase with- 
 out loss or gain. 
 
 The Different Kinds of MecJianical Energy ; of 
 Motion, of Position. There are as many forms of 
 energy as there are distinct categories of phenomena 
 or of varieties in these categories. Physicists dis- 
 tinguish between two kinds of mechanical energy 
 energy of motion and energy of position. The energy 
 of position presents several variants energy of dis- 
 tance, which corresponds to force : of this we have just 
 spoken ; energy of surface, which corresponds to par- 
 ticular phenomena of surface tension ; and energy of 
 volume which corresponds to the phenomena of pressure 
 Energy of motion, kinetic energy, is measured in two 
 ways: as work (the product of force and displacement, 
 W =fs) or as vis viva (half the product of the mass 
 
 into the square of the velocity U = ^-.* 
 
 1 We therefore notice that the measures of force and work 
 bring in mass, space, and time. The typical force, weight, is 
 given by ^.=mg. On the other hand, we have by the laws of 
 
 falling bodies v=gt ; s=\gf*', whence g= ^-, v/=m ^-^-;OT,\{ 
 
 F be the force, M the mass, L the space described, and T the 
 time, we have F = MLT- S , which expresses what are called the 
 dimensions of the force that is to say, the magnitudes with their 
 degree, which enter into its expression. We may thus easily 
 obtain the dimensions of work :
 
 80 LIFE AND DEATH. 
 
 4. THERMAL ENERGY. 
 
 In the elements of physics it is nowadays taught 
 that mechanical work may be transformed into heat, 
 and reciprocally that heat may be transformed into 
 mechanical work. Friction, impact, pressure, and 
 expansion destroy or annihilate the mechanical energy 
 communicated to a body or to' the organs of a 
 machine. With the disappearance of motion we 
 note the appearance of heat. Examples abound. 
 The tyre of a wheel is heated by the friction of the 
 road. Portions of steel are warmed by the impact 
 with stone, as in the old flint and steel. Two pieces 
 of ice were melted by Davy, who rubbed them one 
 against the other, the external temperature being 
 below zero. The boiling of a mass of water caused 
 by a drill was noticed by Rumford in 1790, during 
 the manufacture of bronze cannon. Metal, beaten on 
 an anvil, is heated. A leaden ball flattened against a 
 resisting obstacle shows increase of temperature carried 
 to the point of fusion. Finally, and symbolically, we 
 have the origin of fire in the fable of Prometheus, by 
 rubbing together the pieces of wood which the Hindoos 
 called pramantJia. Correlation is constant between 
 the thermal and mechanical phenomena, a correlation 
 that becomes evident as soon as observers have ceased 
 to restrict themselves to the determination in isolation 
 of the one fact or the other. There is never any real 
 destruction of heat and motion in the true sense of the 
 word ; what disappears in one form appears again in 
 another; just as if something indestructible were ap- 
 pearing in a series of successive disguises. This 
 impression is translated into words when we speak
 
 ENERGY IN GENERAL. 8l 
 
 of the metamorphosis of mechanical into thermal 
 energy. 
 
 The Mechanical Equivalent of Heat. The inter- 
 pretation assumes a remarkable character of precision 
 which at once strikes the mind when physics applies 
 to these transformations the almost absolute accuracy 
 of its measurements. We then find that the rate of 
 exchange is invariable. Transformations of heat into 
 motion, and of motion into heat, take place according 
 to a rigorous numerical la\v, which brings into exact 
 correspondence the quantity of each. Mechanical 
 effect is estimated, as we have seen, by work, that is in 
 kilogrammetres. Heat is measured in calories, the 
 calorie being the quantity of heat necessary to raise 
 from oC to I C a kilogramme of water (Calorie) or 
 one gramme of water (calorie). It is found that 
 whatever may be the bodies and the phenomena 
 which serve as intermediaries for carrying out this 
 transformation, we must always expend 425 kilo- 
 grammetres to create a Calorie, or expend 0-00234 
 Calories to create a kilogrammetre. The number 425 
 is the mechanical equivalent of the Calorie, or, as is 
 incorrectly stated, of the heat It is this constant fact 
 which constitutes the principle of tJie equivalence of /teat 
 and of mechanical work. 
 
 5. CHEMICAL ENERGY. 
 
 We cannot yet actually measure chemical activity 
 directly, but we know that chemical action may give 
 rise to all other phenomenal modalities. It is their 
 most ordinary source, and it is to it that industries 
 appeal to obtain heat, electricity, and mechanical
 
 82 LIFE AND DEATH. 
 
 action. In the steam engine, for instance, the work 
 that is received arises from the combustion of carbon 
 by the oxygen of the air. This gives rise to the heat 
 which vaporizes the water, produces the tension of the 
 steam, and ultimately produces the displacement of 
 the piston. The theory of the steam engine might be 
 reduced to these two propositions: chemical activity 
 gives rise to heat, and heat gives rise to motion ; or to 
 use the language to which the reader by now will be 
 accustomed, chemical energy is transformed into 
 thermal energy, and that into mechanical energy. It 
 is a series of phases and of instantaneous changes, and 
 the exchange is always affected according to a fixed 
 rate. 
 
 TJie Measurement of Chemical Energy. Our know- 
 ledge of chemical energy is less advanced than that of 
 the energies of heat and sensible motion. We have 
 not yet reached the stage of numerical verifications. 
 We can only therefore affirm the equivalence of 
 chemical and thermal energies without the aid of 
 numerical constants, because we do not yet, in the 
 present state of science, know how to measure 
 chemical energy directly. Other known energies are 
 always the product of two factors: the mechanical 
 energy of position, or work, is measured by the 
 product of the force f, and the displacements; work 
 =/?; the mechanical energy of motion, U = ^mv 2 , is 
 measured by the product of the mass into half the 
 square of the velocity. Thermal energy is measured 
 by the product of the temperature and the specific 
 heat; electric energy by the product of the quantity 
 of electricity (in coulombs) and of the electromotive 
 force (in volts). As for chemical energy, we guess 
 that it may be valued directly according to Berthollet's
 
 ENERGY IN GENERAL. 83 
 
 system, adopted by the Norwegian chemists, Guldberg 
 and Waage, by means of the product of the masses 
 and of a force, or co-efficient of affinity, which depends 
 on the nature of the substances which are brought to- 
 gether, on the temperature, and on the other physical 
 circumstances of the reaction. On the other hand. 
 the researches of M. Berthelot enable us in many 
 cases to obtain an indirect valuation in terms of the 
 equivalent heat. 
 
 Its TIL'O Forms. It is interesting to note that 
 chemical energy may also be regarded from the two 
 states of potential and kinetic energy. The coal- 
 oxygen system, to burn in the furnace of the steam 
 engine, must be primed by preliminary work (local 
 ignition), just as the weight that is raised and left 
 motionless at a certain height requires a small 
 effort to be detached from its support. When this 
 condition is fulfilled, energy is at once manifest. 
 We must admit that it existed in the latent state, in 
 the state of chemical potential energy. Under the 
 impulse received, the carbon combines with the 
 oxygen and forms carbonic acid, C + :zO becomes 
 CO 2 ; potential energy is changed into actual chemical 
 energy, and immediately afterwards into thermal 
 energy. \Ve should have only a very incomplete and 
 fragmentary view of the reality of things if we were 
 to consider this phenomenon of combustion in isolation. 
 We must consider it in connection with what has 
 actually created the energy which it is about to 
 dissipate. This antecedent fact is the action of the 
 sun upon the green leaf. The carbon which burns in 
 the furnace of the machine comes from the mine in 
 which it was stored in the form of coal that is to say, 
 of a product which was vegetable in its primitive form,
 
 84 LIFE AND DEATH. 
 
 and which was formed at the expense of the carbonic 
 acid of the air. The plant had separated, at the 
 expense of the solar energy, the carbon from the 
 oxygen to which it was united in the carbonic acid of 
 the atmosphere. It had created the system C + 2O. 
 So that the solar energy produces the chemical poten- 
 tial energy which was so long before it was utilized. 
 Combustion expends this energy in making carbonic 
 acid over again. 
 
 Materialization of Energy. The fertility of the 
 idea of energy is therefore, as we see from all 
 these examples, due to the relations it establishes 
 between the natural phenomena of which it exhibits 
 the necessary relation, destroyed by the excessive 
 analysis of early science. /It shows us that in the 
 world of phenomena there is nothing but trans- 
 formations of energy. /And we regard these trans- 
 formations themselves as the circulation of a kind of 
 indestructible agent which passes from one form of 
 determination to another, as if it were simply putting 
 on a fresh disguise. If our intellect requires images 
 or symbols to embrace the facts and to grasp their 
 relation, it may introduce them here. It will materialize 
 energy, it will make of it a kind of imaginary being, 
 and confer upon it an objective reality. And for the 
 mind, as long as it does not become the dupe of the 
 phantom which it itself has created, this is an 
 eminently comprehensive artifice which enables us 
 to grasp readily the relations between phenomena 
 and their bond of affiliation. 
 
 The world appears to us then, as we said at the 
 outset, constructed with singular symmetry. It offers 
 to us nothing but transformations of matter and 
 transformations of energy ; these two kinds of meta-
 
 ENERGY IX GENERAL. 85 
 
 moiphoses being governed by two laws equally 
 inevitable, the conservation of matter and the con- 
 servation of energy. The first of these laws expresses 
 the. fact that matter is indestructible, and passes 
 from one phenomenal determination to another at 
 a rate of equivalence measured by weight; the 
 second, that energy is indestructible, and that it 
 passes from one phenomenal determination to another 
 at a rate of equivalence fixed for each category by 
 the discoveries of the physicists. 
 
 $ 6. TRANSFORMATIONS OF ENERGY. 
 
 The idea of energy has become the point of departure 
 of a science, Energetics t to the establishment of which 
 a large number of contemporary physicists, among 
 whom are Ostwald, Le Chatdier, etc, have devoted 
 their efforts. It is the study of phenomena, regarded 
 from the point of view of energy. 1 have said that it 
 claims to co-ordinate and to embrace all other sciences. 
 
 The first object of energetics should be the con- 
 sideration of the different forms of energy at present: 
 known, their definition and their measurement. This 
 is what we have just done in broad outline. 
 
 In the second place, each form of energy must be 
 regarded with reference to the rest, so as to determine 
 if the transformation of this into that is directly 
 realizable, and by what means, and, finally, according 
 to what rate of equivalence. This new chapter is a 
 laborious task which would compel us to traverse the 
 whole field of physics. 
 
 Of this long examination we need only concern 
 ourselves here with three or four results which will be
 
 86 LIFE AND DEATH. 
 
 more particularly important in the case of applications 
 to living beings. They refer to mechanical energy, to 
 the relations of thermal energy and chemical energy, 
 to the complete role of thermal energy, and finally to 
 the extreme adaptability of electrical energy. 
 
 1 . Transformation of Mechanical Energy. 
 Mechanical energy may change into every other form 
 of energy, and all others can change into it, with but 
 one exception, that of chemical energy. Mechanical 
 effort does not produce chemical combination. What 
 we know of the part played by pressure in the re- 
 actions of dissociation seems at first to contradict 
 this assertion. But this is only in appearance. Pres- 
 sure intervenes in these operations only as preliminary 
 zvork or priming, the purpose of which is to bring the 
 bodies into contact in the exact state in which they 
 must be for the chemical affinities to be able to enter 
 into play. 
 
 2. Transformation of Thermal Energy ; Priming. 
 Thermal (or luminous) energy does not change 
 directly into chemical energy. In fact, heat and light 
 favour and even determine a large number of chemical 
 reactions; but if we go down to- the foundation ot 
 things we are not long before we feel assured that 
 heat and light only serve in some measure for 
 priming for the phenomenon, for preparing the 
 chemical action, for bringing the body into the 
 physical state (liquid, steam) or to the degree of 
 temperature (400 C. for instance, for the combination 
 of oxygen and hydrogen) which are the preliminary 
 indispensable conditions for the entry upon the scene 
 of chemical affinities. 
 
 On the contrary, chemical energy may really be 
 transformed into thermal energy. We have an
 
 ENERGY IN GENERAL. 87 
 
 instance of this in the reactions which take place 
 without the aid of external energy; and again, in 
 those very numerous cases which, such as the com- 
 bustion of hydrogen and carbon, or the decomposition 
 of explosives, the reactions continue when once primed. 
 I may make a further observation apropos of thermal 
 and photic energy. These are not two really and 
 essentially distinct forms, as was thought in the early 
 days of physics. When we consider things objectively, 
 there is absolutely no light without heat; light and 
 heat are one and the same agent According as it is 
 at this or that degree of its scale of magnitude, it 
 makes a stronger impression on the skin ^sensation of 
 heat) or on the retina (sensation of light} of man and 
 animals. The difference may be put down to the 
 diversity of the work and not to that of the agent. 
 The kinetic theory shows us that the agent is 
 qualitatively identical. The words heat and light 
 only express the chance of the meeting of the radiant 
 agent with a skin and a retina. At the lowest degree 
 of activity this agent exerts no action on the termina- 
 tions of the thermal cutaneous nerves, nor on the 
 optic nerve-terminations. As this degree is raised 
 the former of these nerves are affected 'cold, heat; and 
 are so to the exclusion of the nerves of vision. Then 
 they are both affected (sensation of heat and light), 
 and finally, beyond that, sight alone is affected. The 
 transformation of one energy into the other is there- 
 fore here reduced to the possibility of increasing or 
 decreasing the intensity of the action of this common 
 agent in the exact proportions suitable for passing 
 from one of the conditions to the other; and this is 
 easy when it is a question of going up the scale in the 
 case of light, and, on the contrary, it is not realizable 
 
 7
 
 LIFE AND DEATH. 
 
 directly, that is to say without external assistance, 
 when it is a question of going down the scale again, in 
 the case of heat. 
 
 3. Heat a Degraded Form of Energy. We have 
 seen that thermal energy is not directly transformed 
 into chemical energy. There is yet another restriction 
 in the case of this thermal energy if we study the laws 
 which govern the circulation and the transformations 
 of thermal energy; and the most important comes from 
 the impossibility of transporting it from a body at 
 a lower temperature to a body at a higher temperature. 
 On the whole, and because of these restrictions, 
 thermal energy is an imperfect variety of universal 
 energy, or, as the English physicists call it, a degraded 
 form. 
 
 4. Simple Transformations of Electrical Energy. Its 
 Intermediary Ro.'e. On the other hand, electrical energy 
 represents a perfected and infinitely advantageous form 
 of this same universal energy, and this explains the vast 
 development of its industrial applications within less 
 than a century. It is not that it is better known than 
 the others in its nature and in the secret of its action. 
 On the contrary, there is more dispute than ever as to 
 its nature. To some, electricity, which is transported 
 and propagated with the speed of light, is a real flux 
 of the ether as was taught by Father Secchi, who 
 compared it to a current of water in a pipe. It would 
 do its work, just as the water of the mill does its 
 work by flowing over a wheel or through a turbine. 
 Electricity, like water in this case, would not be 
 an energy in itself, but a means of transporting 
 energy. 
 
 To others, such as Clausius, Hertz, and Maxwell, it 
 is not so; the electric current is not a transport of
 
 ENERGY IN GENERAL- 89 
 
 energy. It is a state of the ether of a peculiar, 
 specific kind, periodically produced (electric oscilla- 
 tion), and propagated with a speed of the order of 
 that of light. 
 
 However that may be, what constitutes the essential 
 peculiarity of electrical energy, and what causes its 
 value, is that it is an incomparable agent of trans- 
 formation. Every known form of energy may be 
 converted into it, and inversely, electrical energy may 
 be changed with the utmost facility into all other 
 energies. This extreme adaptability assigns to it 
 the part of an intermediary between the other less 
 tractable agents. Mechanical energy, for instance, 
 lends itself with difficulty to the production of light, 
 that is to say, to a metamorphosis into photic energy 
 (a variety of thermal energy). A fall of water cannot 
 be directly utilized for lighting purposes. The 
 mechanical work of this fall, which cannot be 
 exploited in its present form, serves to set in 
 motion in industrial lighting the installations, the 
 electric machines, and the dynamos which feed the 
 incandescent lamps. Mechanical work is changed 
 into electrical energy, and it, in its turn, into thermal 
 or photic energy. Electricity has here played the part 
 of a useful intermediary. 
 
 The last part of energetics must be consecrated to 
 the study of the general principles of this science. 
 These principles are two hi number, the principle of 
 the conservation of energy, or Mayer's principle, and 
 the principle of the transformation of energy, or 
 Carnot's principle. The doctrine of energy thus 
 reduces to two fundamental laws the multitude of 
 laws, often known as "general," to which natural 
 science is subject.
 
 go LIFE AND DEATH. 
 
 7. THE PRINCIPLE OF THE CONSERVATION 
 OF ENERGY. 
 
 In all that precedes, the principle of conservation has 
 intervened at every step. In fact, the very idea of 
 energy is connected with the existence of this principle. 
 We first discover the idea in the work of the philo- 
 sophical mathematicians who established the founda- 
 tions of mechanics: Newton, Leibniz, d'Alembert, 
 and Helmholtz ; or of inductive physicists such as 
 Lord Kelvin. Its experimental proof, sketched by 
 Marc Seguin and R. Mayer, is due to Colding and 
 Joule. 
 
 It is Independent of the Kinetic Theory. Mayer's 
 law states that energy is indestructible; that all 
 phenomenality is nothing but a transformation of 
 energy from one form to another, and that this 
 transformation takes place either at equal values, 
 or rather, at a certain rate of equivalence. This is 
 what takes place when thermal energy is transformed 
 into mechanical energy (equivalent 425). This rate 
 of equivalence is fixed by the researches of physicists 
 for each category of energy. 
 
 It will be noticed that this law and this theory of 
 energy, which is always presented by authors of 
 elementary books as a consequence of the kinetic 
 theory, is quite independent of it. In the preceding 
 lines we have not even mentioned its name. We 
 have not assumed that all phenomena are movements 
 or transformations of movements, whether sensible or 
 vibratory; we have not affirmed that what was 
 passing from one phenomenal determination to 
 another was the vis viva of the motion, as is the case
 
 ENERGY IX GEXERAL. QI 
 
 in the impact of elastic bodies. No doubt the kinetic 
 theory- affords us a very striking image of these truths 
 which are independent of it; but it may be false: and 
 the theory of energy* which assumes the minimum of 
 possible hypotheses would yet be true. 
 
 // contains a great many other Principles. 
 The principle of the conservation of energy contains 
 a large number of the most general principles of 
 science. It may be shown without much difficulty 
 that, for example, it contains the principle of the 
 inertia of matter, laid down by Galileo and Descartes ; 
 that of the equality of action and reaction, due to 
 Newton ; and even that of the conservation of matter. 
 or rather of mass, due to Lavoisier. And finally, it 
 contains the experimental law of equivalence con- 
 nected with the name of the English physicist Joule, 
 from which may be derived the Law of Hess and the 
 principle of the initial and final states which we owe 
 to Berthelot 
 
 // inrofats the Lav: of Equivalence : Here we may- 
 be content with noticing that the law of the conserva- 
 tion of energy involves the existence of relations of 
 equivalence between the different varieties. A certain 
 quantity* of a given energy, measured, as we have 
 seen, by* the product of two factors, is equivalent to a 
 certain fixed quantity of quite a different form of 
 energy into which it may be converted. The laws 
 which govern energetic transformations therefore con- 
 tain, from both the qualitative and the quantitative 
 points of view, all the connections of the phenomena 
 of the universe. To study these laws in their detail is 
 the task that physics must take upon itselt 
 
 The conversion one into the other of the different 
 forms of energy by means of equivalents is only a
 
 Q2 LIFE AND DEATH. 
 
 possibility. It is subject, in fact, to all sorts of 
 restrictions, of which the most important are due to 
 the second principle. 
 
 8. CARNOT'S PRINCIPLE. ITS GENERALITY. 
 
 The second fundamental principle is that of the 
 transformations of equilibrium, or of the conditions 
 of reversibility, or again, Carnot's principle. This 
 principle, which first assumed a concrete form in 
 thermodynamics, has been very widely extended. It 
 has reached a degree of generality such that contem- 
 porary theoretical physicists such as Lord Kelvin, Le 
 Chatelier, etc., consider it the universal law of 
 physical, mechanical, and chemical equilibrium. 
 
 Carnot's principle contains, as was shown by G. 
 Robin, d'Alembert's principle of virtual velocities, 
 and according to physicists of to-day, as we have just 
 remarked, it contains the laws peculiar to physico- 
 chemical equilibrium. The application of this prin- 
 ciple gives us the differential equations from which 
 are derived numerical relations between the different 
 energies, or the different modalities of universal 
 energy. 
 
 Its Character. It is very remarkable that we can- 
 not give a general enunciation of this principle which 
 by its revealing power has changed the face of 
 physics. This is because it is less a law, properly so 
 called, than a method or manner of interpreting the 
 relations of the different forms of energy, and par- 
 ticularly the relations of heat and mechanical energy. 
 
 Conversion of Work into Heat and Vice-versa. The 
 conversion of work into heat is accomplished without 
 difficulty. For example, the hammering of a piece of
 
 ENERGY IX GENERAL. ' 93 
 
 iron on an anvil may bring it to a red heat. A shell 
 which passes through an armour plate is heated, and 
 melts and volatilizes the metal all round the hole it 
 has made. By utilizing mechanical action under the 
 form of friction all energy can be converted into heat 
 
 The inverse transformation of heat into work, on 
 the contrary, cannot be complete. The best motor 
 that we can think of, and a fortiori the best we can 
 realize, can only transfcrm a third or a fourth of the 
 heat with which it is supplied. 
 
 This is an extremely important fact It is of in- 
 calculable importance to natural philosophy, and may 
 be ranked among the greatest discoveries. 
 
 Higher and Degraded Forms of Energy. Of these 
 we may give an account by distinguishing among the 
 forms of universal energy higher forms, and lozwr or 
 degraded forms. Here we have the principle of the 
 degradation of energy on its trial, and it may be 
 regarded as a particular aspect of the second principle 
 of energetics, or Carnot's principle. Mechanical 
 energy is a higher form. Thermal energy is a lower 
 form, a degraded form, and one which has degrees in 
 its degradation. Higher energy, in general, may be 
 completely converted into lower energy; for example, 
 work into heat : the slope is easy to descend, but it is 
 difficult to retrace our steps; lower energy can be 
 only partially transformed into higher energy, and the 
 fraction thus utilizable depends upon certain con- 
 ditions on which Carnot's principle has thrown con- 
 siderable light 
 
 Thus, although in theory the thermal energy of a 
 body may have its equivalent in mechanical energy, 
 the complete transformation is only realizable from 
 the latter to the former, and not from the former to
 
 94 UFE AND DEATH. 
 
 the latter. This is due to a condition of thermal 
 energy which is called temperature. The same 
 quantity of thermal energy, of heat, may be stored 
 in the same thermal body at different temperatures. 
 If this quantity of thermal energy is in a very hot 
 body \ve can utilize a large portion of it ; if it is in a 
 relatively cold body we can only convert a small 
 portion of it into mechanical work. Thus the value 
 of energy, i.e., its capacity of being converted into 
 a higher and more useful form, depends on tem- 
 perature. 
 
 The Capacity of Conversion depends on Temperature. 
 The conversion of heat into work assumes two 
 bodies of different temperatures, the one warm and 
 the other cold ; a boiler and a condenser. Every 
 thermal machine conveys a certain amount of heat 
 from the boiler to the condenser, and what is not thus 
 carried is changed into work. This residue is only a 
 small fraction, a quarter, or at most a third of the 
 heat employed, and that, too, in the theoretically 
 perfect machine, in the ideal machine. 
 
 This output, this utilizable fraction depends on the 
 fall of temperature from the higher to the lower level, 
 just as the work of a turbine depends on the height 
 of the waterfall which passes through it. But it also 
 depends on the conditions of this fall, on the 
 accessory losses from radiation and conduction. 
 However, Carnot has shown that the output is the 
 same, and a maximum for the same fall of temperature, 
 whatever be the working agent (steam, hot air, etc.), 
 and whatever be the machine provided that this 
 agent, this substance which works is not exposed to 
 accessory losses, that it is never in contact with a 
 body having temperature different to its own or
 
 ENERGY IX GEXERAL- 95 
 
 ajain, that it is connected only with bodies im- 
 permeable to heat 
 
 This is Carnot's principle in one of its concrete 
 forms. 
 
 A machine which realizes this condition, that the 
 agent (steam, alcohol, ether) is in relation, at all 
 phases of its function, with bodies which can neither 
 take heat from it nor give heat to it, is a rercrsiblc 
 machine. Such a machine is perfect. The fraction 
 of heat that it transforms into motion is constant ; it 
 is a maximum ; it is independent of the motor, of its 
 organs, of the agent : it accurately expresses the 
 transformability of the heat agent into a mechanical 
 agent under the given conditions. 
 
 The Degradation and Restoration of Energy. The 
 fraction not utilized, that which is carried to the 
 condenser at a lower temperature, is degraded. \l 
 can only be used by a new agent, in a new machine 
 in which the boiler has exactly the same temperature 
 as the condenser in the first machine, and the new 
 condenser has a lower temperature, and so on. The 
 proportion of utilizable energy thus goes on diminish- 
 ing. Its utilization requires conditions more and 
 more difficult to realize. The thermal energy loses its 
 potential and its value, and is further and further de- 
 graded as its temperature approaches that of the 
 surrounding medium. 
 
 The degraded energy, theoretically, has kept its 
 equivalent value but, practically, it is incapable of 
 conversion. However, it is shown in physics that it 
 can be raised and re-established at its initial leveL 
 But for that purpose another energy must be utilized 
 and degraded for its benefit. 
 
 The End of the Universe. What we have just
 
 96 LIFE AND DEATH. 
 
 seen with respect to heat and motion is to some 
 degree true of all other 'forms of energy, as Lord 
 Kelvin has shown. The principle of the degradation 
 of energy is very general. Every manifestation of 
 nature is an energetic transformation. In each of 
 these transformations there is a degradation of energy 
 />, a certain fraction is lowered and becomes less 
 easily transformable. So that the energy of the 
 universe is more and more degraded; the higher 
 forms are lowered to the thermal form, the latter 
 increasing at temperatures which become more and 
 more uniform. The end of the universe, from this 
 point of view, would then be unity of (thermal) energy 
 in uniformity of temperature. 
 
 Importance of the Idea of Energy in Physiology, 
 I have said that the application of Carnot's principle 
 furnished numerical relations between the different 
 energetic transformations. 
 
 The science of living beings has not yet reached 
 that point of development at which it is possible for 
 us to obtain its numerical relations. However, the 
 consideration of energy and the principle of conserva- 
 tion has altered the outlook of physiology on many 
 questions which are of the highest importance. 
 
 The determination of the sources from which plants 
 and animals draw their vital energies; the mediate 
 transformation of chemical energy into animal heat in 
 nutrition, or into motion in muscular contraction ; the 
 chemical evolution of foods ; the study of soluble 
 ferments all these questions are of considerable 
 importance when we wish to understand the 
 mechanisms of life. They are therefore depart- 
 ments of physiological energetics in which great 
 advances have already been made.
 
 CHAPTER II. 
 
 ENERGY IN BIOLOGY. 
 
 i. Energy in Living Beings. 2. The First Law of Biological 
 Energetics: All Vital Phenomena are Energetic Trans- 
 formations. 3. Second Law : The Origin of Vital 
 Energy is in Chemical Energy. Functional Activity and 
 Destruction.! 4. Third Law: The Final Form of 
 Energetic Transformation in the Animal is Thermal 
 Energy. Heat is an Excretum. 
 
 THE theory of energy was thought of and utilized in 
 physiology before it was introduced into physics, in 
 which it has exercised such an extraordinary influence. 
 Robert Mayer was a physicist and a doctor. Helm- 
 holtz was equally at home in physiology and in physics. 
 From the outset both had seen in this new idea a 
 powerful instrument of physiological research. The 
 volume in which Robert Mayer expounded, in 1845, 
 his remarkable views on organic movement in relation 
 to nutrition, and Helmholtz' commentary leave us in 
 no doubt in this respect. The essay on the mechanical 
 equivalent of heat, of a more particularly physical 
 character, is six years later than the earlier work. 
 
 The Relations betiveen Energetics and Biology. 
 
 The theory of energy is therefore only returning to 
 
 its cradle; and to that cradle it returns with all the 
 
 sanction of physical proof, as the most general theory 
 
 97
 
 98 LIFE AND DEATH. 
 
 ever proposed in natural philosophy, and the theory 
 least encumbered with hypotheses. It reduces all 
 particular laws to two fundamental principles that 
 of the conservation of energy, which contains the 
 principles of Galileo and Descartes, of Newton, of 
 Lavoisier, Joule's law, Hess's law, and Berthelot's 
 principle of the initial and final states ; and also 
 Carnot's principle, from which are deduced the laws 
 of physico-chemical and chemical equilibrium. These 
 two principles therefore sum up the whole of natural 
 science. They express the necessary relation of all 
 the phenomena of the universe, their uninterrupted 
 gentic connection, and their continuity. 
 
 A priori there would be little likelihood that a 
 doctrine, so universal and so thoroughly verified in 
 the physical world, could be restricted, and thus 
 be useless to the living world. Such a supposi- 
 tion would be contrary to the scientific method, which 
 always tends to the generalization and the explanation 
 of elementary laws. The human mind has always 
 proceeded thus : it has applied to the unknown 
 order of living phenomena the most general laws of 
 contemporary physics. 
 
 This application has been found legitimate, and has 
 been justified by experiment whenever it has been a 
 question of the laws or of the really fundamental or 
 elementary conditions of phenomena. It has, on the 
 other hand, however, been unfortunate when it has 
 stopped short of secondary characteristics. When we 
 now concede the subjection of living beings to these 
 general laws of energetics, we are following a 
 traditional method. There is no doubt that this 
 application is legitimate, and that experiment will 
 justify it a posteriori.
 
 ENERGY IX BIOLOGY. 99 
 
 I will therefore grant, as a provisional postulate, 
 the consequences of which will have to be ultimately 
 justified, that the Hying and inanimate world alike 
 show us nothing but transformations of matter and 
 transformations of energy. The word phenomenon 
 will have no other signification, whatever be the 
 circumstances under which the phenomenon occurs. 
 The varied manifestations which translate the activity 
 of living beings thus correspond to transformations of 
 energy, to conversions of one form into another, in 
 conformity with the rules of equivalence laid down by 
 the physicists. This conception may be formulated 
 in the following manner: TIic pJienomena of life have 
 t/ie same claim to be energetic metamorphoses as t/u 
 other phenomena of nature. 
 
 This postulate is the foundation of biological 
 energetics. It may be useful to give some ex- 
 planation relative to the signification, the origin, and 
 the scope of this statement. 
 
 Biological energetics is nothing but general physi- 
 ology reduced to the principles that are common to all 
 the physical sciences. Robert Mayer and Helmholtz 
 gave the best description of this science, and laid 
 down its limits by defining it as " the study of the 
 phenomena of life regarded from the point of view 
 of energy." 
 
 i. ENERGY AT PLAY IN LIVING BEINGS. 
 COMMON OR PHYSICAL ENERGIES. VITAL 
 ENERGIES. 
 
 Our first object will be to define and to enumerate the 
 energies at play in living beings ; to determine their 
 more or less easy transformations from one to another,
 
 100 LIFE AND DEATH. 
 
 to bring to light the general laws which govern those 
 transformations, and finally to apply them to the 
 detailed study of phenomena. This programme may 
 be divided into four parts. 
 
 In the physical world the specific forms of energy 
 are not numerous. When we have mentioned 
 mechanical, chemical, radiant (thermal and photic) 
 energies, electrical energy, with which is blended 
 magnetic energy, we have exhausted the catalogue of 
 natural agents. 
 
 But is this list for ever closed ? Are vital energies 
 comprised in this list? These are the first questions 
 which we must ask ourselves. 
 
 The iatro-mechanical school, on a priori grounds 
 give an affirmative answer. No doubt there are in the 
 living organism many manifestations which are pure 
 physical manifestations of known energies, mechanical, 
 chemical, thermal, etc. But are all the manifestations 
 of the living being of this order? Are they all, hence- 
 forth, reducible to the categories and varieties of energy 
 which are investigated in physics ? This is the claim 
 of the mechanical school. But the claim is rash. Our 
 fundamental postulate affirms, in principle, that uni- 
 versal energy is manifested in living beings ; but, as a 
 matter of fact, there is no reason for the assertion that 
 it does not assume particular forms, according to the 
 circumstances peculiar to the conditions under which 
 they are produced. 
 
 These special forms of energy manifested in the con- 
 ditions suitable to living beings would swell the list 
 drawn up by the physicists. And it would not be the 
 first instance of an extension of this kind. The 
 history of science records many remarkable cases. 
 Scarcely a century has passed since we first heard of
 
 ENERGY IX BIOLOGY. IOI 
 
 electrical energy. This discovery in the world of 
 energy, which took place, so to speak, before our 
 very eyes, of an agent which plays so large a part 
 in nature, clearly leaves the door open to other 
 surprises. 
 
 We shall therefore concede that there may be 
 other forms of ejiergy at work in living beings than 
 those we ajrgadyjcnow in the physical world. This 
 reservation would enable us to discover at once the 
 essential characteristics by which vital phenomena 
 are henceforth reduced to universal physics, and 
 the purely formal differences still distinguishing 
 them. 
 
 If there arj really special energies in living beings, 
 our monistic postulate leads us to assert that these 
 energies are homogeneous with the others, and that 
 they do not differ from them more than they differ 
 among themselves. It is probable that some day 
 they will be discovered external to living bodies, if 
 the material conditions (which it is always possible to 
 imagine; are realized externally to them. And if we 
 must admit that the peculiarity of the medium is 
 such that these forms must remain indefinitely 
 peculiar to living beings, we may assert with every 
 confidence that these special energies do not obey 
 special laws. They are subject to the two funda- 
 mental principles of Robert Mayer and CarnoL 
 They are exchanged according to fixed laws with 
 the other physical forms of energies at present 
 known. 
 
 To sum up, then, we must establish three categories 
 in the forms of energy which express the phenomena 
 of vitality. 
 
 In the first place, most of these energies are those
 
 IO2 LIFE AND DEATH. 
 
 which have already been studied and recognized in 
 general physics. They are the same energies : 
 chemical, thermal, mechanical, with their char- 
 acteristics of mutability, their lists of equivalents, 
 ami their actual and potential states. 
 I In the second place, it may happen, and it prob- 
 ably will happen, as it happened in the last century 
 in the case of electricity, that some new form of 
 energy will be discovered belonging to the universal 
 order as to the living order. This will be a conquest 
 of general physics as well as of biology. 
 
 And finally we may rigorously and provisionally 
 admit a last category of vital energies properly so 
 called. 
 
 It is difficult to give much precision to the idea of 
 vital energies properly so called. 
 
 It will be easier to measure them by means of 
 equivalents than to indicate their nature. Besides, 
 this is the ordinary rule in the case of physical agents. 
 We can measure them, although we know not what 
 they are. 
 
 Characteristics of Vital Energies. We see why we 
 cannot exhibit with precision, a priori^ the nature of 
 vital energies. In the first place, they are expressed 
 by what takes place in the tissues in activity, and 
 this cannot at present be identified with the known 
 types of physical, chemical, and mechanical pheno- 
 mena. This is a first, intrinsic reason for not being 
 able to distinguish them readily, since what takes 
 place is not distinguished by the phenomenal appear- 
 ances to which we are accustomed. 
 
 There is a second, intrinsic reason. These vital 
 phenomena are intermediary, as we shall see, between 
 manifestations of known energies. They lie between
 
 ENERGY IN BIOLOGY. 103 
 
 a chemical phenomenon which always precedes them, 
 and a thermal phenomenon which always follows 
 them. They are lost sight of, as it were, between 
 manifestations which strike our attention. Generally 
 speaking, intermediary energies often escape us 
 even in physics. Only the extreme manifestations 
 are clearly seen. In the presence of the organism 
 we are, as it were, in electric lighting works which 
 are run by a fall of water, and at first we only 
 see the mechanical energy of the falling water, 
 of the turbine and dynamo at work, and the 
 photic energy of the lamps which give the light. 
 Electrical energy, an intermediary, which has only 
 a transient existence, does not impose itself on our 
 attention. 
 
 And so vital energies for this twofold reason, in- 
 trinsic and extrinsic, are not readily apparent To 
 reveal them, the careful analysis of the physiologists 
 is required. They are acts, in most cases silent and 
 invisible, which we should scarcely recognize but by 
 their effects, after they have terminated in familiar, 
 phenomenal forms. This is, for example, what goes 
 on in the muscle in process of shortening, in the nerve 
 carrying the nervous influx, in the secreting gland. 
 And this is what constitutes the different forms of 
 energy which w r e call vital properties. M. Chauveau 
 and M. Laulanie use the phrase physiological u'ork 
 to distinguish them. Vital energy would be prefer- 
 able. It better expresses the analogy of this special 
 form with the other forms of universal energy; it 
 helps us better to understand that we must hence- 
 forth consider it as exchangeable by means of 
 equivalents with the energies of the physical world 
 just as they are exchangeable one with another. 
 
 8
 
 104 LIFE AND DEATH - 
 
 2. FIRST LAW OF BIOLOGICAL ENERGETICS. 
 
 It is easy to understand, after these remarks, the 
 significance and the scope of this assertion which 
 contains the first principle of biological energetics 
 namely, that the phenomena of life have the same 
 claim to be called energetic metamorphoses as the 
 other phenomena of nature. 
 
 Irreversibility of Vital Energies. However, there 
 is one characteristic of vital energies which deserves 
 the closest attention. Their transformations have a 
 direction which is in some measure inevitable. They 
 descend a slope which they never re-ascend. They 
 appear to be irreversible. Ostwald has rightly in- 
 sisted on this fundamental characteristic, which no 
 doubt is not that of all the phenomena of the living 
 being without exception, but which is certainly that of 
 the most essential phenomena. There are reversible 
 phenomena in organisms ; there are energetic trans- 
 formations which may take place from one form of 
 energy to another, or vice versa. But the most 
 characteristic phenomena of vitality do not act in 
 this way. We shall presently see that most functional 
 physiological acts begin with chemical and end with 
 thermal action. The series of energetic transforma- 
 tions takes place in an inevitable direction, from 
 chemical to thermal energy. The order of succession 
 of ordinary energies is thus determined in the machine 
 of the organism, and therefore by the conditions of 
 the machine. \The order of transformation of vital 
 energies is still more rigorously regulated, and the 
 phenomena of life evolve from childhood to ripened 
 years, and thence to old age, without a possible 
 returnA
 
 ENERGY IN BIOLOGY. IO5 
 
 The laws of biological energetics are three in num- 
 ber. First of all, there is the fundamental principle 
 which we have just developed, and which is, so to 
 speak, laid down a priori; and there are two other 
 principles, those established by experiment and 
 summing-up, as it were, the multitude of known 
 physiological effects. Of these two experimental 
 laws, one refers to the origin and the other to the 
 termination of tJu energies developed in living beings. 
 
 3. SECOND LAW OF BIOLOGICAL ENERGETICS. 
 
 The Oigin of Vital Energy. Vital energies have 
 their origin in one of the external or common energies 
 not in any one we choose, as might be supposed. 
 but in one only: chemical energy. The third principle 
 will show us that they terminate in another energy or 
 a few others, also completely fixed. 
 
 It follows that the phenomena of life must appear 
 to us to be a circulation of energy which, starting from 
 one fixed point in the physical world, returns to that 
 world by a few points, also fixed, after a transient 
 passage through the animal organism. 
 
 Or more precisely, it is a transposition from the 
 realm of matter into the world of energy, of the idea 
 of the "vital vortex of Cuvier and the biologists. 
 They defined life by its most constant property 
 nutrition. Nutrition was exactly this current of 
 matter which the organism obtains from without by 
 alimentation, and which it throws out again by ex- 
 cretion ; and the even momentary interruption of 
 which, if complete, would be the signal of death. 
 The cycle of energy is the exact counterpart of 
 this cycle of matter.
 
 106 LIFE AND DEATH. 
 
 The second truth taught us by general physiology, 
 a truth which physiology learned from experiment, is 
 enunciated as follows :^The maintenance of life con- 
 sumes none of its energy. It borrows from the external 
 world all the energy which it expends , and borrows it in 
 the form of 'potential chemical energy^} This is a trans- 
 lation into the language of energetics of the results 
 acquired in animal physiology during the last fifty years. 
 No comment is needed to exhibit the importance of 
 such a truth. It reveals the origin of animal activity. 
 It reveals the source from which proceeds that energy 
 which at some moment of its transformations in the 
 animal organism will be a vital energy. 
 
 The prinmm movens of vital activity is, therefore, 
 according to this law, the chemical energy stored up 
 in the immediate principles of the organism. 
 
 Let us try to follow, for a moment, this energy 
 through the organism and to specify the circumstances 
 of its transformations. 
 
 Organic Functional Activity, and the Destruction of 
 Reserve-stuff. Let us suppose then, for this purpose, 
 that our attention is directed to a given limited part 
 of this organism, to a certain tissue. Let us seize 
 it, so to speak, by observation at a given moment, 
 and let us make an examination of the functional 
 activity starting from this conventional moment. 
 This functional activity, like all other vital pheno- 
 mena, will be the result, as we have just explained, of 
 a transformation of the potential chemical energy 
 contained in the materials held in reserve in the 
 tissue. This is our first perceptible fact. This 
 energy, when disengaged, will furnish to the vital 
 action the means by which it may be prolonged. 
 
 There is, then, a functional destruction. There is, at
 
 ENERGY IX BIOLOGY. J.OJ 
 
 the beginning of the functional process, and by a 
 necessary effect of that very process, a liberation of 
 chemical energy; and that can only take place by a 
 decomposition of the immediate principles of the 
 tissue, or, as we may say, by a destruction of organic 
 material. Claude Bernard insisted on this considera- 
 tion, that the vital function is accompanied by a 
 destruction of organic material. " When a movement 
 is produced, when a muscle is contracted, when 
 volition and sensibility are manifested, when thought 
 is exercised, when a gland secretes, then the substance 
 of the muscles, of the nerves, of the brain, of the 
 glandular tissue, is disorganized, is destroyed, and is 
 consumed." Energetics enables us to grasp the 
 deeply-seated reason of this coincidence between 
 chemical destruction and the functional activity, the 
 existence of which Claude Bernard intuitively sus- 
 pected. A portion of organic material is decomposed, 
 is chemically simplified, becomes less complex, and 
 loses in this kind of descent the chemical energy 
 which it contained in its potential state. It is this 
 energy which becomes the very texture of the vital 
 phenomenon. 
 
 It is clear that the reserve of energy thus expended 
 must be replaced, because the organism remains in 
 equilibrium. Alimentation provides for this. 
 
 How does it provide for it? This is a question 
 which deserves detailed examination. We cannot 
 incidentally treat it in full ; we can only indicate its 
 main features. 
 
 How the supply of Resene Stuff is kept tip. We 
 know that food does not directly replace the reserve 
 of energy consumed by the functional activity. It is 
 not its potential chemical energy which replaces,
 
 108 LIFE AND DEATH. 
 
 purely and simply, the energy brought into play, 
 consumed, or, better still, transformed in the active 
 organ, or tissue. Food as it is introduced, inert food, 
 does not, in fact, take up its place as it z's, without 
 undergoing changes in that organ and that tissue, in 
 order to restore the status quo ante. 
 
 Before building up the tissue it will have undergone 
 various modifications in the digestive apparatus. It 
 will have also undergone changes in the circulatory 
 apparatus, in the liver, and in the very organ we are 
 considering. It is after all these changes that assimila- 
 tion takes place. It will find its place and will have 
 then passed into the state of reserve. 
 
 The food digested, modified, and finally incorporated 
 as an integral part in the tissue in which it will be ex- 
 pended, is therefore in a new state, differing more or 
 less from its state when it was ingested. It is a part 
 of the living tissue in the state of constitutive reserve. 
 Its potential chemical energy is not the same as that 
 of the food introduced. It may differ from it very 
 remarkably in consequence of sudden alterations. 
 
 We do not know for certain at the expense of what 
 category of foods this or that given organ builds up 
 its reserve stuff. There is a belief, for instancej 
 according to M. Chauveau, that the muscle does its 
 work at the expense of the reserve of glycogen which 
 it contains. The potential chemical energy of this 
 substance would be a source of muscular mechanical 
 energy. But we do not know exactly at the expense 
 of what foods, albumenoids, fats, or carbohydrates 
 the muscle builds up the reserve of glycogen expended 
 during its contraction. It is probable that it builds it 
 up at the expense of each of the three categories after 
 the various more or less simple alterations undergone
 
 ENERGY IN BIOLOGY. IOQ 
 
 by the materials in the digestive tube, the blood, the 
 liver, or other organs. 
 
 This building up of reserve stuff, the complement 
 and counterpart of functional destruction, is not chemi- 
 cal synthesis. It is, on the contrary, generally, and 
 on the whole, a simplification of the food that has 
 been introduced. This is true, at least as far as the 
 muscle is concerned. However, to this operation, 
 Claude Bernard has given the name of organizing 
 syntJiesis, but the phrase is not a happy one. But 
 in no case was the eminent physiologist deceived 
 as to the character of the operation. " The organ- 
 izing synthesis," says he, "remains internal, silent, 
 hidden in its phenomenal expression, gathering 
 together noiselessly the materials which will be 
 expended." 
 
 These considerations enable us to understand the 
 existence of the two great categories into which the 
 eminent physiologist divides the phenomena of animal 
 life: the phenomena of the destruction of reservc- 
 stuff correspond ing to functional facts that is to say 
 expenditures of energy; and the plastic pJtenomena of 
 the building-up of resen-cs of organic regeneration, cor- 
 responding to functional repose i.e., to the supply of 
 food to the tissues. 
 
 Distinction between Active Protoplasm and Resen-e- 
 stuff. If it is not exactly in these terms that Claude 
 Bernard formulated this fruitful idea, it is at any 
 rate in this way that it is to be interpreted. This 
 can be done by giving it a little more precision. 
 We apply more rigorously than that great physio- 
 logist the distinction drawn by himself between really 
 active and living protoplasm and the reserve-stuff 
 which it prepares. To the latter is restricted the
 
 HO LIFE AND DEATH. 
 
 destruction by the functional activity and the building 
 up by repose. 
 
 The classification of Claude Bernard is strictly true 
 for reserve-stuff. It is easy to criticize the wavering 
 and, as it were, dimly groping expressions in 
 which the celebrated physiologist has shrouded his 
 ideas. The old adage will excuse him: Obscuritate 
 rerum verba obscurantur. In the depths of his ignor- 
 ance he had a flash of genius ; perhaps he did not find 
 the definitive and, as it were, clearly-cut formula de- 
 fining what was in his mind. But, in this respect, he 
 has left his successors an easy task. 
 
 The Law of Functional Assimilation. The progress 
 of physiological knowledge compels us therefore to 
 distinguish in the constitution of anatomical elements 
 two parts the materials of reserve-stuff w& the really 
 active and living protoplasm. We have just seen how 
 the reserve-stuff behaves, alternately destroyed by 
 functional activity, and built up afterwards by the 
 ingestion of food, followed by the operations of di- 
 gestion, elaboration, and assimilation. It remains to 
 ask how this really living and protoplasmic matter 
 behaves. Does it follow the same law ? Is it de- 
 stroyed during the functional activity, and is it after- 
 wards replaced? As to this we can express no 
 opinion. M. le Dantec fills a gap in our knowledge, 
 in this respect, by an hypothesis. He assumes that 
 this essentially active matter grows during functional 
 activity, and is destroyed during repose. This is what 
 he calls the law of functional assimilation. The 
 protoplasm would therefore behave in an exactly 
 contrary manner to the reserve-stuff. It will be its 
 counterpart. But this is only an hypothesis which, 
 in the present state of our knowledge, cannot be
 
 ENERGY IN BIOLOGY. Ill 
 
 verified by experiment We are at liberty to 
 assert either that the protoplasm increases by 
 functional activity or that it is destroyed. Neither 
 the arguments nor the objections pro or con have any 
 decisive value. The facts alleged on either side are 
 capable of too many interpretations. 1 
 
 The only favourable argument (not demonstrative) 
 is furnished by energetics. It is this. The re-building 
 of the protoplasm is not like the organization of reserve- 
 stuff^ a slightly complicated or even simplified pheno- 
 menon, as happens in the case of the reserve of 
 muscular glycogen. The glycogen, in fact, is built up 
 at the expense of foods chemically more complex. 
 It is, on the contrary, a clearly synthetic pheno- 
 menon, certainly of chemical complexity, since it ends 
 in building up the active protoplasm which is, in some 
 measure, of the highest scale of complexity. Its for- 
 mation at the expense of the simplest alimentary 
 materials requires, therefore, an appreciable quantity 
 of energy. 
 
 The assimilation which organizes the active proto- 
 plasm therefore requires energy for its realization. 
 Now, at the moment of functional activity, and by a 
 necessary consequence thereof, the chemical destruc- 
 
 1 The reason is to be found in the large number of indeter- 
 minates in the problem we have to solve. It will be sufficient 
 to enumerate them : the two substances which exist in the 
 anatomical element, protoplasm and reserve-stuff, to which 
 are attributed contrary roles ; the two conditions attributable 
 to the protoplasm, of manifested or latent activity ; the faculty 
 possessed by both of being prolonged for an indeterminate 
 period, and of encroaching each on its protagonist when its 
 existence is at stake. Here are more elements than are neces- 
 sary to explain the positive or negative results of all the 
 experiments in the world.
 
 112 LIFE AND DEATH. 
 
 tion or simplification of the substance of reserve takes 
 place. Here is something that meets the case, and 
 we may note the coincidence. It does not mean that 
 the disposable energy is really used to increase the 
 protoplasm, nor that the protoplasm itself is thereby 
 increased. It merely signifies that the wherewithal 
 exists to provide for that increase if it takes place. 
 
 It is therefore possible that the active protoplasm 
 follows the law of functional assimilation ; but it is 
 certain that the reserve-stuff follows the law laid down 
 by Claude Bernard. 
 
 All these considerations definitely result in the 
 confirmation of this second law of general physiology, 
 according to which all vital energies are borrowed 
 from the potential chemical energy of the reserve-stuff 
 of alimentary origin. 
 
 4. THE THIRD LAW OF BIOLOGICAL ENERGETICS. 
 
 The third law of biological energetics is also drawn 
 from experiment. It relates no longer to the point of 
 departure of the cycle of animal energy, but to its 
 final position. Tlie energetic transformations of tJie 
 animal end in tliermal energy. 
 
 This is the most novel part of the theory, and, if we 
 may say so, that least understood by physiologists 
 themselves. The energy resulting from the chemical 
 potential of food, having passed through the organism 
 (or simply through the organ which we are considering 
 in action), and having given rise to phenomenal ap- 
 pearances more or less diversified, more or less dim or 
 clear, obscure or obvious, which are the characteristic 
 or still irreducible manifestations of vitality, finally
 
 EXERGY IX BIOLOGY. 113 
 
 returns to the physical world. This return takes 
 place (with certain exceptions which will be presently 
 indicated) under the ultimate form of thermal energy. 
 This we are taught by experiment. The phenomena 
 of functional activity are exothermal. 
 
 Real vital phenomena thus lie between the chemical 
 energy which gives rise to them, and the thermal 
 phenomena to which they in their turn give rise. The 
 place of the vital fact in the cycle of universal energy 
 is therefore completely determined. This conclusion 
 is of the utmost importance to biology. It may be 
 expressed in a concise formula which sums up in a 
 few words all that natural philosophy can teach as to 
 energetics applied to living beings. " Vital energy is 
 a transformation of chemical energy into thermal 
 energy." 
 
 Exceptions. There are some exceptions to the 
 rigour of this statement, but they are not many in 
 number. We must first of all remark that it applies 
 to animal life alone. 
 
 In the rase of vegetables, looked at as a whole, the 
 law must be modified. Their vital energy has another 
 origin, and another final form. Instead of being the 
 destroyers of chemical potential energy, they are its 
 creators. They build up by means of the inert and 
 simple materials afforded them by the atmosphere 
 and the soil, the immediate principles by which their 
 cells are filled. Their vital functional activity forms by 
 synthesis of the reserves, carbo-hydrates (sugars and 
 starches), fats, albuminoid nitrogenous materials that 
 is to say, the same three principal categories of foods 
 as those used by ?nifiraSsL 
 
 And to return to the latter, it should be observed 
 that thermal energy is not the only final form of vital
 
 114 LIFE AND DEATH. 
 
 energy, as this dogmatic statement would have it 
 supposed. It is only the principle of the final forms. 
 The cycle of energy occasionally terminates in 
 mechanical energy (phenomena of motion) and in 
 a less degree in other energies ; such as, for example, 
 the electrical energy produced by the functional activity 
 of the nerves and muscles in all animals, or in the 
 functional activity of special organs in rays, torpedo- 
 fish, and the malapterurus electricus, or finally, in the 
 photic energy of phosphorescent animals. But these 
 are secondary facts. 
 
 Heat is an Excretuni. The third principle of bio- 
 logical energetics may be therefore thus enunciated : 
 Vital energy in its final form becomes thermal energy. 
 This principle teaches us that if chemical energy is 
 the primitive generating form of vital energies, 
 thermal energy is the form of waste, of emunctory, 
 the degraded form as the physicists would say. Heat 
 is in the dynamical order an excretion of animal 
 life, as urea, carbonic acid and water, are excreta in 
 the substantial order. By a false interpretation of 
 the principle of the mechanical equivalence of heat, or 
 through ignorance of Carnot's principle, certain 
 physiologists have fallen into error when they still 
 speak of the transformation of heat into motion or into 
 into electricity in the animal organism. Heat is trans- 
 formed into nothing in the animal organism. It is dis- 
 sipated. Its utility arises not from its energetic value, 
 but from the part it plays as a primer in the chemical 
 reactions, as has been explained with reference to the 
 general characteristics of chemical energy. 
 
 The Effect of Energetics on our Knowledge of the 
 Relations of the Universe. The consequences of these 
 principles of energetic physiology, which give us so
 
 ENERGY IN BIOLOGY. 115 
 
 much and which are so clear, are of the greatest 
 importance from the practical as well as from the 
 theoretical point of view. 
 
 In the first place, they show us the position and the 
 rank of the phenomena of life in the universe as a 
 whole. They throw fresh light on the noble harmony 
 of the animal and vegetable kingdoms which Priestley, 
 Ingenhousz, Senebier. and the chemical school of the 
 beginning of the nineteenth century discovered, and 
 which was expounded by Dumas with incomparable 
 lucidity and brilliance. Energetics is expressed in a 
 line. "The animal world expends the energy ac- 
 cumulated by the vegetable world." 1 It extends these 
 views beyond the living kingdoms. It shows how the 
 vegetable world itself draws its activity from the 
 energy radiated by the sun, and how animals restore 
 it again, in dissipated heat, to the cosmic medium. 
 It extends the harmony of the two kingdoms to the 
 whole of nature. The new science makes of the 
 whole universe one connected system. 
 
 From a more limited point of view, and so that we 
 may not restrict ourselves to a consideration of the 
 domain of animal physiology, the laws of energetics 
 sum up and explain a multitude of facts and of 
 experimental laws for example, the law of the inter- 
 mittence of physiological activity, the facts of fatigue, 
 the role and the general principles of alimentation, 
 and the conditions of muscular contraction.
 
 CHAPTER III. 
 
 ALIMENTARY ENERGETICS. 
 
 Various Problems of Alimentation. i. Food the source of 
 Energy and Matter. The two forms of Energy afforded by 
 Food Vital Energy, Thermal Energy. Food the source 
 of Heat. The role of Heat. 2. Measure of the output of 
 Energy by the Calometric Method by the Chemical 
 Method. 3. The regular type of Food, Biothermogenic, 
 and the irregular type, Thermogenic. 4. Food considered 
 as the source of Heat. The Law of Surfaces. The limits 
 of Isodynamics. 5, Plastic role of Food. Preponderance 
 of Nitrogenous Foods, 
 
 AMONG the problems on which energetics has 
 thrown a vivid light we have mentioned alimentation, 
 muscular contraction, and, more general still, the 
 intermittence of vital functional activity. We shall 
 begin with the study of alimentation. 
 
 The Different Problems of Alimentation. What is a 
 food? In what does alimentation consist? The 
 dictionary of the Academic will give us our first 
 answer. It tells us that the word food is applied to 
 "every kind of matter, whatever may be its nature, 
 which habitually serves or may serve for nutrition." 
 This is very well put, but here again we must know 
 what nutrition is, and that is not a simple matter; in 
 fact, it practically means whatever is usually placed 
 on the table in a civilized and polished society. But 
 116
 
 ALIMENTARY ENERGETICS. 1 17 
 
 it is just the profound reasons for this traditional 
 practice that we are trying to discover. 
 
 The problem of alimentation may be looked at in a 
 thousand ways. It is culinary, no doubt, and gas- 
 tronomic; but it is also economical and social, 
 agricultural, fiscal, hygienic, medical, and even moral. 
 But first and foremost, it is physiological. It com- 
 prises and assumes the knowledge of the general 
 composition of foods, of their transformations in the 
 digestive apparatus, and their comparative utility in 
 the maintenance and the sound functional activity 
 of the organism. To this first group of subjects for 
 our discussion are attached others relating to the 
 effects of inanition, of insufficient alimentation, and of 
 over-feeding. And in order to throw light on all 
 these aspects of the problem of alimentation, we have 
 to lay bare the most intimate and delicate reactions by 
 which the organism is maintained and recruited, and, 
 in the words of a celebrated physiologist, " to pene- 
 trate into the kitchen of vital phenomena." And here 
 neither Apicius, nor Brillat-Savarin, nor Berchoux, 
 nor the moralists, nor the economists are of any use 
 to us as guides. We must appeal to the scientists, 
 who, following the example of Lavoisier, Berzelius, 
 Regnault, and Liebig, have applied to the study of 
 living beings the resources of general science, and 
 have thus founded cJiemical biology. 
 
 This branch of science developed considerably in 
 the second half of the nineteenth century. It has now 
 its methods, its technique, its chairs at the universities, 
 its laboratories, and its literature. It has particularly 
 applied itself to the study of the " material changes" 
 or the metabolism of living beings, and with that 
 object in view it has done two things In the first
 
 Il8 LIFE AND DEATH. 
 
 place, it has determined the composition of the 
 constituent materials of the organism; then analyzing 
 qualitatively and quantitatively all that penetrates into 
 that organism in a given time that is to say, all the 
 alimentary or respiratory ingesta, and all that issues 
 from the organism, i.e., all the excreta, all the egesta, 
 it has drawn up nutritive balance sheets, corre- 
 sponding to the various conditions of life, whether 
 naturally or artificially created. And thus we can 
 determine the alimentary regimes which give too 
 much, and which give too little, and which finally 
 restore equilibrium. 
 
 We do not propose to give a detailed account of 
 this scientific movement. This may be done in mono- 
 graphs. All we wish to indicate here is the most 
 general result of these laborious researches that is 
 to say, the laws and the doctrines which are derived 
 from them, and the theories to which they have given 
 birth. It is by this alone that they are brought into 
 relation with general science, and may therefore 
 interest the reader. The facts of detail are never 
 lacking to the historian ; it is more profitable to show 
 the movement of ideas. The theories of alimentation 
 bring into conflict very different conceptions of 
 the vital functional activity. And here we find a 
 confused medley of opinions on which it is not without 
 interest to endeavour to throw some light. 
 
 i. FOOD, A SOURCE OF ENERGY AND MATTER. 
 
 Definitions of Food. Before the introduction into 
 physiology of the notion of energy, no one had 
 succeeded in giving an exact idea and a precise 
 definition of food and alimentation. Every physio-
 
 ALIMENTARY EXERGETICS. IIQ 
 
 legist and medical man who attempted it had failed, 
 and this for various reasons. 
 
 The general cause of this failure was that most de- 
 finitions, popular or technical, interposed the condition 
 that the food must be introduced into the digestive 
 apparatus. "It is," said they, * a substance which 
 when introduced into the digestive tube undergoes, 
 etc., etc" But plants draw food from the soil, and 
 they possess no digestive apparatus; many animals 
 have no intestinal tube; and in the case of certain 
 rotifera, the females possess a digestive apparatus, 
 while the males have none. Nevertheless all animals 
 feed. 
 
 On the other hand, there are other substances than 
 those which use the digestive tract for the purpose of 
 entering the organism, and which are eminently useful 
 or necessary to the maintenance of life. In par- 
 ticular we may mention oxygen. 
 
 The distinctive feature of food is its utility when 
 conveniently introduced or employed to the living 
 being. Claude Bernard's definition is this: A sub- 
 stance taken in the external medium " necessary for the 
 maintenance of the phenomena of the healthy organism 
 and for the reparation of the losses it constantly 
 suffers." " A substance which supplies an element 
 necessary for the constitution of the organism, or 
 which diminishes its disintegration? (stored-up food); 
 this is the definition of C Voit, the German physio- 
 logist. M. Dnclaux says, in his turn, but in far too 
 general terms, that it is a substance which contributes 
 to assure the sound functional activity of any of the 
 organs of the living being. None of these ways of 
 describing food gives a complete idea. 
 
 Food, tlu Source of Energy and Matter. The inter- 
 
 9
 
 120 LIFE AND DEATH. 
 
 vention of the notion of energy enables us more 
 completely to understand the true nature of food. 
 We must, in fact, have recourse to the energetic con- 
 ception if we desire to take into account all that the 
 organism requires from food. It not only requires 
 matter, but also, and most important of all, energy. 
 
 Investigators so far concentrated their thoughts ex- 
 clusively on the necessity of a supply of matter that 
 is to say, they only looked upon one side of the 
 problem. The living body presents, at each of its 
 points, an uninterrupted series of disintegrations and 
 reconstitutions, the materials being supplied from 
 without by alimentation, and rejected by excretion. 
 Cuvier gave to this unceasing circulation of ambient 
 matter throughout the vital world the name of vital 
 vortex, and he rightly saw in it the characteristic of 
 nutrition, and the distinctive feature of life. 
 
 This idea of the cycle of matter has been com- 
 pleted in our own time by that of the cycle of 
 energy. All the phenomena of the universe, and 
 therefore those of life, are conceived of as energetic 
 transformations. We now look at them in their relation- 
 ship instead of considering them individually as of old. 
 Each has an antecedent and a consequent unity with 
 which it is connected in magnitude by the law of 
 equivalents taught us by contemporary physics. And 
 thus we may conceive of their succession as the 
 cycle of a kind of indestructible agent, which changes 
 only apparently, or assumes another form as it passes 
 from one to the other, but its magnitude remains 
 unaltered. This is energy. Thus, in the living being 
 there is not only a circulation of matter, but also a 
 circulation of energy. 
 
 The most general result of research in physiological
 
 ALIMENTARY ENERGETICS. 121 
 
 chemistry from the time of Lavoisier down to our own 
 day has been to teach us that tlie antecedent of the 
 vital phenomenon is always a cJumical pJienomenon. 
 The vital energies are derived from the potential 
 chemical energy accumulated in the immediate con- 
 stituent principles of the organism. In the same way 
 tfu consequent pJienomenon of tJte vital pJienomenon is in 
 general a tliermal phenomenon. The final form of 
 vital energy is thermal energy. These three assertions 
 as to the nature, the origin, and the final form of vital 
 phenomena constitute the three fundamental prin- 
 ciples, the three laws, of biological energetics. 
 
 Food, a Source of Heat. It is not qua source of Jieat 
 tttatfood is the source of vital energy. The place of 
 vital energy in the cycle of universal energy is com- 
 pletely determined. It lies between the chemical 
 energy which is its generating form and the thermal 
 energy which is its form of disappearance, of break- 
 down, the "degraded form," as the physicists say. 
 Hence we have a result which can be immediately 
 applied in the theory of food namely, that heat is in 
 the dynamical order an excretum of the animal life 
 rejected by the living being, just as in the substantial 
 order, urea, carbonic acid and water, are the materials 
 used up and again rejected by it We therefore must 
 not think of the transformation in the animal organ- 
 ism of heat into vital energy, as certain physiologists 
 always do. Nor must we think, with Beclard, of its 
 transformation into muscular movement ; or, as others 
 have maintained, into animal electricity. This is not 
 only an error of doctrine but an error of fact It 
 proceeds from a false interpretation of the principle of 
 the mechanical equivalent of heat and a misunder- 
 standing of Carnot's principle. Thermal energy does
 
 122 LIFE AND DEATH. 
 
 not repeat the course of the energetic flux in the 
 animal organism. The heat is not transformed into 
 anything. It is simply dissipated. 
 
 The Part played by Animal Heat as a Condition of 
 Physiological Manifestations. Does this mean that 
 heat is useless to life in the very beings in which it is 
 most abundantly produced i.e., in man and in the 
 warm-blooded vertebrates ? So far from this being so, 
 it is necessary to life. But its utility has a peculiar 
 character which must neither be misunderstood nor 
 exaggerated. It is not transformed into chemical 
 or vital reactions, but merely creates for them a 
 favourable condition. 
 
 According to the first principle of energetics, for 
 the vital fact to be derived from the thermal fact, the 
 heat must be preliminarily transformed into chemical 
 energy, since chemical energy is necessarily an ante- 
 cedent and generating form of vital energy. Now 
 this regressive transformation is impossible according 
 to the current theories of general physics. The part 
 played by heat in the act of chemical combination is 
 that of a primer to the reaction. It consists in placing 
 the reacting bodies, by changing their state or by 
 modifying their temperature, in the condition in which 
 they ought to be for the chemical forces to come into 
 play. For example, in the combination of hydrogen 
 and oxygen by setting light to an explosive mixture, 
 heat only acts as a primer to the phenomenon, because 
 the two gases which are passive at ordinary tempera- 
 tures, require to be raised to 400 C. before chemical 
 affinity comes into play. And so it is with the 
 reactions which go on in the organism. They have 
 a maximum temperature, and the part played by 
 animal heat is to furnish them with it.
 
 ALIMENTARY ENERGETICS. 123 
 
 It follows that heat intervenes in animal life in two 
 capacities first and foremost as uceretum, or end of 
 the vital phenomenon, of physiological -a.~ork\ and on 
 the other hand, as a condition or primer of die chemical 
 reactions of the organism ; and generally, as a favour- 
 able condition for the appearance of the physiological 
 manifestations of living matter. Thus, it is not 
 dissipated in sheer waste. 
 
 I was led to adopt these views some years ago 
 from certain experiments on the role played in food by 
 alcohol I did not then know that they had already 
 been expressed by one of the masters of contemporary 
 physiology, M. A. Chauveau, and that they were 
 related in his mind to a series of conceptions and of 
 researches of great interest, in the development of 
 which I have since then taken a share. 
 
 Two Forms of Energy supplied to Animals bj Feed. 
 To say that food is simultaneously a supply of 
 energy and a supply of matter, is really to express in 
 a single sentence the fundamental conception of 
 biology, in virtue of which life brings into play no 
 substratum or characteristic dynamism. According 
 to this, the living being appears to us as the 
 seat of an incessant circulation of matter and energy, 
 starting from the external world and returning 
 to it All food is nothing but this matter and this 
 energy. All its characteristics, our views as to its 
 role, its evolution, all the rules of alimentation are 
 simple consequences of this principle, interpreted by 
 the light of energetics. 
 
 And first of all, let as ask what forms of energy are 
 afforded by food? It is easy to see that there are 
 two food is essentially a source of chemical energy ; 
 and secondarily and accessorily, it is a source of heat
 
 124 LIFE AND DEATH. 
 
 Chemical energy is the only energy, according to the 
 second law of energetics, which may be transformed 
 into vital energy. It is true at any rate for animals ; 
 for in plants it is otherwise. There the vital cycle has 
 neither the same point of departure nor the same final 
 position. The circulation of energy does not take 
 place in the same manner. 
 
 On the other hand, and this we are taught by the 
 third law, energy brought into play in vital pheno- 
 mena is finally liberated and restored to the physical 
 world in the form of heat. We have just said that 
 this release of heat is employed in raising the tem- 
 perature of the living being. It is animal heat. 
 
 Thus there are two forms of energy supplied by 
 food, chemical and thermal. 
 
 It must be added that these are not the only forms, 
 but the principal, and by far the most important It is 
 not absolutely true that heat is the only outcome of the 
 vital cycle. It is only so in the subject in repose, con- 
 tented to live idly without doing external mechanical 
 work, without lifting a tool or a weight, even that of its 
 own body. And again, speaking in this way, we neglect 
 all the movements and all the mechanical work which 
 is done without exercise of the volition, by the beating 
 of the heart and of the arteries, the movements of 
 respiration, and the contractions of the digestive tube. 
 
 Mechanical work is, in fact, another possible termi- 
 nation of the cycle of energy. But there is no 
 longer anything necessary or inevitable in this, since 
 motion and the use of force are in a certain measure 
 subordinated to the capricious volition of the animal. 1 
 
 1 There is another reason why the role of mechanical energy, 
 compared with that of thermal energy, is reduced, in the partition 
 of afferent, alimentary energy at least, in animals which have not
 
 ALIMENTARY ENERGETICS. 125 
 
 At other times, again, it is an electrical phenomenon 
 which terminates the vital cycle, and it is, in fact, in 
 this way that things happen in the functional activity 
 of the nerves and muscles in all animals, and in the 
 functional activity of the electrical organ in fish, 
 such as the ray and the torpedo. Finally, the ter- 
 mination may be a photic phenomenon, and this is 
 what happens in phosphorescent animals. 
 
 It is idle to diminish the power of these principles 
 by proceeding to enumerate the whole of the ex- 
 ceptions to their validity. We know perfectly well 
 that there are no absolute principles in nature. Let 
 us say, then, that the energy which temporarily 
 animates the living being is furnished to it by the 
 external world under the exclusive form of potential 
 chemical energy; but that, if there is only one door of 
 entry, there are two exits. It may return to the ex- 
 ternal world in the principal form of thermal energy 
 and in the accessory form of mechanical energy. 
 
 2. MEASUREMENT OF THE SUPPLY OF 
 ALIMENTARY ENERGY. 
 
 Calorinutric Method. From what has preceded it 
 is clear that if the energetic flux which circulates 
 through the animal emerges, in toto, in the state of 
 heat, the measurement of this heat becomes the 
 
 to do excessive work. The unit of heat, the Calorie, is equivalent 
 to 425 unite of work /^L, to 425 kilogrammetres. In the animal 
 at rest, the number of kilogrammetres representing the different 
 quantities of work done is small, the number of corresponding 
 Calories is 425 times smaller. It becomes almost negligeable in 
 comparison with the considerable number of Calories dissipated 
 in the form of heat.
 
 126 "LIFE AND DEATH. 
 
 measurement of the vital energy itself, for the origin 
 of which we must go back to the food. If the flux is 
 divided into two currents, mechanical and thermal, 
 they must both be measured and the sum of their 
 values taken. If the animal does not produce me- 
 chanical work, and all ends in heat, we have only to 
 capture, by means of a calorimeter, this energetic flux 
 as it emerges, and thus measure in magnitude and 
 numerically the energy in motion in the living being. 
 Physiologists use for this purpose various types of 
 apparatus. Lavoisier and Laplace used an ice calori- 
 meter that is to say, a block of ice in which they 
 shut up a small animal, such as a guinea-pig; they 
 then measured its thermal production by the quantity 
 of ice it caused to melt. In one of their experiments, 
 for instance, they found that a guinea-pig had melted 
 341 grammes of ice in the space of ten hours, and had 
 therefore set free 27 Calories. 
 
 But since those days more perfect instruments have 
 been invented. M. d'Arsonval employed an air calori- 
 meter, which is nothing but a differential thermometer 
 very ingeniously arranged, and giving an automatic 
 record. Messrs. Rosenthal, Richet, Him and Kauf- 
 mann, and Lefevre have used more or less simplified 
 or complicated air calorimeters. Others, following 
 the example of Dulong and Despretz, have used 
 calorimeters of air and mercury, or with Liebermester, 
 VVinternitz, and J. Lefevre (of Havre), have had 
 recourse to baths. Here, then, there is a considerable 
 movement of research which has led to the discovery 
 of very interesting facts. 
 
 Measurement of t/te Supply of Alimentary Energy 
 by the CJiemical MetJiod. We may again reach our 
 result in another way. Instead of surprising the cur-
 
 ALIMENTARY ENERGETICS. I2~ 
 
 rent of energy as it emerges and in the form of 
 heat, we may try and capture it at its entry in the 
 form of potential chemical energy. 
 
 The evaluation of potential chemical energy may 
 be effected with the same unit of measurement as the 
 preceding that is to say, the Calorie. If we consider 
 man and mammals, for example, we know that there 
 is only apparently an infinite variety in their foods. 
 We may say that they feed on only three substances. 
 It is a very remarkable fact that all the complexity 
 and multiplicity of foods, fruits, grains, leaves, animal 
 fiqffc and vegetable products of which use is made, 
 reduce to so great a simplicity and uniformity, that all 
 these substances are of three types only: albuminoids, 
 such as albumen or white of egg foods of animal 
 origin or varieties of albumen ; carbo-hydrates, which 
 are more or less disguised varieties of sugar; and 
 finally, fats. 
 
 Here, then, from the chemical point of view, leaving 
 out certain mineral substances, are the principal 
 categories of alimentary substances, Here, with the 
 oxygen that is brought in by respiration, is every- 
 thing that penetrates the organism. 
 
 And now, what comes out of the organism ? Three 
 things only, water, carbonic acid, and urea. But the 
 former are the products of the combustion of the 
 latter. If we consider an adult organism in perfect 
 equilibrium, which varies throughout the experiment 
 neither in weight nor in composition, we may say that 
 the receipts balance the expenditure. Albumen, sugar, 
 fat, plus the oxygen brought in, balance quantitatively 
 the water, carbonic acid, and urea expelled. Things 
 happen, in fact, as if the foods of the three categories 
 were burned up more or less completely by the oxygen.
 
 128 LIFE AND DEATH. 
 
 It is this combustion that we have known since the 
 days of Lavoisier to be the source of animal heat. 
 We can easily determine the quantity of heat left by 
 albumen passing into the state of urea, and by the 
 starch, the sugars, and the fats reduced to the state of 
 water and carbonic acid. This quantity of heat does 
 not depend on the variety of the unknown inter- 
 mediary products which have been formed in the 
 organism. Berthelot has shown that this quantity of 
 heat which measures the chemical energy liberated by 
 these substances is identical with the quantity ob- 
 tained by burning the sugar and the fats in a chemical 
 apparatus, in a calorimetric bomb, until we get carbonic 
 acid and water, and by burning albumen till we get 
 urea. This result is a consequence of Berthelot's 
 principle of initial and final states. The liberated 
 heat only depends on the initial and final states, and 
 not on the intermediary states. The heat left in the 
 economy by the food being the same as that left in 
 the calorimetric bomb, it is easy for the chemist to 
 determine it. It has thus been discovered that one 
 gramme of albumen produces 4.8 Calories, one gramme 
 of sugar 4.2 Calories, and one gramme of fat 9.4 
 Calories. We thus gather what a given ration a mix- 
 ture in certain proportions of these different kinds of 
 foods supplies to the organism and what energy 
 it gives it, measured in Calories. 
 
 The calculation may be carried out to a high degree 
 of accuracy if, instead of confining ourselves to the 
 broad features of the problem, we enter into rigorous 
 detail. It is only, in fact, approximately that we have 
 reduced all foods to albumen, sugar, and fat, and all 
 excreta to water, carbonic acid, and urea. 
 
 The reality is a little more complicated. There
 
 ALIMENTARY ENERGETICS. I2Q 
 
 are varieties of albumen, carbo-hydrates, and fatty 
 bodies, the heats of combustion of which in the 
 organism oscillate in the neighbourhood of the num- 
 bers 4.8, 4.2, and 9.4. Each of these bodies has been 
 individually examined, and numerical tables have 
 been drawn up by Berthelot, Rubner, Stohmann, Van 
 Noorden, etc. The tables exhibit the thermal value 
 or energetic value of very different kinds of foods. 
 
 In our climate, the adult average man, doing no 
 laborious work, daily consumes a maintenance ration 
 composed, as a rule, of 100 grammes of albuminoids, 
 49 grammes of fats, and 403 grammes of carbo- 
 hydrates. This ration has an energetic value of 2,600 
 Calories. 
 
 It is therefore, thanks to the victories won in the 
 field of thermo-chemistry, and to the principles laid 
 down since 1864 by M. Berthelot, that this second 
 method of attack on nutritive dynamism has been 
 rendered possible. Physiologists, by the aid of these 
 methods, have drawn up balance-sheets of energy for 
 living beings just as they had previously established 
 balance-sheets of matter. 
 
 Now, it is precisely researches of this kind that we 
 have indicated here as a consequence of biological 
 energetics, which in reality have helped to build up 
 that principle. These researches have shown us that, 
 in conformity with the principles of tJiermodynamics, 
 there was not, in fact, in the organism, any trans- 
 formation of heat into mechanical work, as the 
 physiologists for a short time supposed, on the 
 authority of Berthelot With the help of our theory 
 this mistake is no longer possible. The doctrine of 
 energetics shows us in fact the current of energy 
 dividing itself, as it issues from the living being, into
 
 130 LIFE AND DEATH. 
 
 two divergent branches, the one thermal and the 
 other mechanical, external the one to the other 
 although both issuing from the same common trunk, 
 and having between them no relation but this, that 
 the sum of their discharges represents the total of the 
 energy in motion. Let us now translate these very 
 simple notions into the more or less barbarous jargon 
 in use in physiology. We shall be convinced as we 
 go on of the truth of the saying of Buffon, that "the 
 language of science is more difficult to learn than the 
 science itself." We shall say, then, that chemical 
 energy, that the unit of weight of the food which may 
 be placed in the organism, constitutes the alimentary 
 potential, the energetic value of this substance, its 
 dynamogenic power. It is measured in units of heat, 
 in Calories, which the substance may leave in the 
 organism. The evaluation is made according to the 
 principles of thermo-chemistry, by means of the 
 numerical tables of Berthelot, Rubner, and Stohmann. 
 The same number also expresses the thermogenic 
 power, virtual or theoretical, of the alimentary sub- 
 stance. This energy being destined to be transformed 
 into "vital energies (Chauveau's pJiysiological work, 
 pJiysiological energy), the dynamogenic or thermogenic 
 value of the food is at the same time its biogenetic 
 value. Two weights of different foods which supply 
 the organism with the same number of Calories, i.e. 
 for which these numerical values are the same, will be 
 called isodynamic or isodynamogenic, isobiogenetic, iso- 
 energetic weights. They will be equivalent from the 
 point of view of their alimentary value. And finally, 
 if, as is usually the case, the cycle of energy ends in 
 the production of heat, the food which has been 
 utilized for this purpose has a real tliennogenic value,
 
 ALIMENTARY ENERGETICS. 131 
 
 identical with its theoretical thermogenic value. In 
 this case it might be determined experimentally by 
 direct calorimetry, measuring the heat produced by 
 the animal supposed absolutely unchanged and iden- 
 tical before and after the consumption of the food. 
 
 3. DIFFERENT TYPES OF FOODS. THE REGULAR, 
 BlOTHERMOGENIC TYPE AND THE IRREGULAR, 
 THERMOGENIC TYPE. 
 
 Food is a source of thermal energy for the organ- 
 ism because it is decomposed within it, and undergoes 
 within it a chemical degradation. Physiological 
 chemistry tells us that whatever be the manner in 
 which it is broken up, it always results in the same 
 body and always sets free the same quantity of heat. 
 But if the point of departure and the point of arrival 
 are the same, it is possible that the path pursued is 
 not constantly identical. For example, one gramme 
 of fat will always give the same quantity of heat, 
 94 Calories, and will always come to its final state 
 of carbonic acid and water ; but from the fat to 
 the mixture of carbonic acid gas and water there 
 are many different intermediaries. In a word we 
 get the conception of varied cycles of alimentary 
 evolutions. 
 
 From the point of view of the heat produced it has 
 just been said that these cycles are equivalent But 
 are they equivalent from the vital point of view? 
 This is an essential question. 
 
 Let us imagine the most ordinary alternative. 
 Food passes from the natural to the final state after 
 being incorporated with the elements of the tissues,
 
 132 LIFE AND DEATH. 
 
 and after having taken part in the vital operations. 
 The chemical potential ' only passes into thermal 
 energy after having passed through a certain inter- 
 mediary phase of vital energy. This is the normal 
 case, the regular type of alimentary evolution. It may 
 be said in this case that the food has fulfilled the 
 whole of its function, it has served for the vital 
 functional activity before producing heat. It has 
 been biothermogenic. 
 
 The irregular or pure tJiermogenic type. And now 
 let us conceive of the most simple irregular or 
 aberrant type. Food passes from the initial to the 
 final state without incorporation in the living cells of 
 the organism, and without taking part in the vital 
 functional activity. It remains confined in the blood 
 and the circulating liquids, but it undergoes in the 
 end, however, the same molecular disintegration as 
 before, and sets free the same quantity of heat. 
 Its chemical energy changes at once into thermal 
 energy. Food is a pure thermogen. It has fulfilled 
 only one part of its work. It has been of slight 
 vital utility. 
 
 Does this ever occur in reality? Are there foods 
 which would be only pure tJiermogens that is to 
 say, which would not in reality be incorporated with 
 the living anatomical elements, which would form no 
 part of them either in a state of provisory constituents 
 of the living protoplasm, or in the state of reserve- 
 stuff; which would remain in the internal medium, in 
 the blood and the lymph, and would there undergo 
 their chemical evolution? Or again, if the whole of 
 the food does not escape assimilation, would it be 
 possible for part to escape it ? Would it be possible 
 for one part of the same alimentary substance to be
 
 ALIMENTARY ENERGETICS. 133 
 
 incorporated, and for the rest to be kept in the blood 
 or the lymph, in the circulating liquids ad limina 
 corporis, so to speak ? In other words, can the same 
 food be according to circumstances a biotJiermogen or 
 a pure thermogen? Some physiologists Pick of 
 Wurzburg, for instance have claimed that this is 
 really the case for most nitrogenous elements, carbo- 
 hydrates, and fats; all would be capable of evolving 
 according to the two types. On the other hand, Zuntz 
 and von Mering have absolutely denied the existence 
 of the aberrant or pure thermogenic type. No sub- 
 stances would be directly decomposed in the organic 
 liquids apart from the functional intervention of the 
 histological elements. Finally, other authors teach 
 that there is a small number of alimentary substances 
 which thus undergoes direct combustion, and among 
 them is alcohol. 
 
 Liebig's Superfluous Consumption. Liebig's theory 
 of superfluous consumption and Voit's theory of the 
 circulating albumen assert that the proteid foods 
 undergo partial direct combustion in the blood vessels. 
 The organism only incorporates what is necessary 
 for physiological requirements. As for the surplus 
 of the food that is offered it, it accepts it, and, so 
 to speak, squanders it; it burns it directly; and 
 we have a "sumptuary" consumption, consumption 
 de luxe. 
 
 In this connection arose a celebrated discussion 
 which still divides physiologists. If we disen- 
 gage the essential body of the discussion from all 
 that envelops it, we see that it is fundamentally a 
 question of deciding whether a food always follows the 
 same evolution whatever the circumstances may be, 
 and particularly when it is introduced in great excess.
 
 134 LIFE AND DEATH. 
 
 Liebig thought that the superabundant part, escaping 
 the ordinary process, was destroyed by direct com- 
 bustion. He affirmed, for instance, that nitrogenous 
 substances in excess were directly burned in the blood 
 instead of passing through their usual cycle of vital 
 operations. We might express the same idea by 
 saying that they then undergo an accelerated 
 evolution. Instead of passing through the blood in 
 the anatomical element, to return in the dismem- 
 bered form from the anatomical element to the blood, 
 their breaking up takes place in the blood itself. 
 They save a displacement, and therefore in reality 
 remain external to the construction of the living 
 edifice. Their energy, crossing the intermediary vital 
 stage, passes with a leap from the chemical to the 
 thermal form. Liebig's doctrine reduced to this 
 fundamental idea deserved to survive, but mistakes 
 in minor details involved its ruin. 
 
 Voifs Circulating Albumen. A few years later 
 C. Voit, a celebrated physiological chemist of Munich, 
 revived it in a more extravagant form. He held 
 that almost the whole of the albuminoid element 
 is burned directly in the blood. He interpreted 
 certain experiments on the utilization of nitro- 
 genous foods by imagining that these substances 
 when introduced into the blood were divided as a 
 result of digestion into two parts: the one very small, 
 which was incorporated with the living elements, and 
 passed into the stage of organized albumen, the other, 
 corresponding to the greater part of the alimentary 
 albumen, remained mingled with the blood and 
 lymph, and was subjected in this medium to direct 
 combustion. This was circulating albumen. In this 
 theory the tissues are almost stable ; the organic
 
 ALIMENTARY ENERGETICS. 135 
 
 liquids alone are subjected to oxydizing transforma- 
 tions, to nutritive metabolism. The accelerated 
 evolution, which Liebig considered as an exceptional 
 case, was to C. Voit the rule. 
 
 Current Ideas as to the R&U of Foods. The ideas 
 of to-day are not those of Voit ; but they do not. 
 however, differ from them essentially. We no longer 
 admit that the greater part of the ingested and 
 digested albumen remains confined in the circulating 
 medium external to the anatomical elements. It is 
 held, with Pfliiger and the school of Bonn, that it 
 penetrates the anatomical element and is incorpor- 
 ated in it ; but in agreement with Voit it is believed 
 that a very small part is assimilated to the really 
 living matter, to the protoplasm properly' so called : 
 the greater part is deposited in the cellular element 
 as reserve-stuff. The material, properly so called, of 
 the living machine does not undergo destruction and 
 reparation as extensively as our predecessors supposed. 
 There is no need for great reparation. On the con- 
 trary, the physiological activity consumes to a great 
 extent the reserve-stuff. And the greater part of 
 the food, after having undergone suitable elabora- 
 tion, serves to replace the reserve-stuff destroyed 
 in each anatomical element by the vital functional 
 activity. 
 
 Experimental Facts. Among the facts which 
 brought physiologists of the school of Voit to believe 
 that most foods do not get beyond the internal 
 medium, there is one which may well be mentioned 
 here. It has been observed that the consumption of 
 oxygen in respiration increases notably (about a fifth 
 of its value) immediately after a meal What does 
 this mean ? The interval is too short for the digested 
 
 10
 
 136 LIFE AND DEATH. 
 
 alimentary substances to have been elaborated and 
 incorporated in the living cells. It is supposed that 
 an appreciable time is required for this complete 
 assimilation. The products of alimentary digestion 
 are therefore in all probability still in the blood, and 
 in the interstitial liquids in communication with it 
 The increase of oxygen consumed would show that a 
 considerable portion of these nutritive substances 
 absorbed and passed into the blood would be oxy- 
 dized and then and there destroyed. But this 
 interpretation, however probable it may be, does not 
 really fit in with the facts in such a way that we may 
 consider it as proved. Certain experiments by Zuntz 
 and Mering are opposed to the idea that combustion 
 in the blood is easy. These physiologists injected 
 certain oxydizable substances into the vessels without 
 being able to detect any instantaneous oxidation. 
 It is only fair to add that against these fruitless 
 attempts other more fortunate experiments may be 
 quoted. 
 
 Category of Purely TJiennogenic Foods ; with Ac- 
 celerated Evolution. Alcohol. Acids of Fruits. 
 The accelerated evolution of foods an evolution 
 which takes place in the blood, that is to say outside 
 the really living elements remains, therefore, very 
 uncertain as far as ordinary food is concerned. It 
 has been thought that it was a little less uncertain 
 as far as the special category of alcohol, acids of 
 fruits, and glycerine is concerned. 
 
 Some authors consider these bodies as pure 
 thermogens. When alcohol is ingested in moder- 
 ate doses, they say that about a tenth of the 
 quantity absorbed becomes fixed in the living tissues; 
 the rest is "circulating alcohol." It is oxidized
 
 ALIMENTARY ENERGETICS. 37 
 
 directly in the blood and in the lymph, without inter- 
 vening in the vital functions other than by the heat 
 it produces. From the point of view of the energetic 
 theory these are not real foods, because their potential 
 energy is not transformed into any kind of vital 
 energy, but passes at once to the thermal form. On 
 the other hand, other physiologists look upon alcohol 
 as really a food. According to them everything is 
 called a food which is transformed in the organism 
 with the production of heat ; and they measure the 
 nutritive value of a substance by the number of 
 Calories it can give up to the organism. So that 
 alcohol would be a better food than carbohydrated 
 and nitrogenous substances. A definite quantity of 
 alcohol, a gramme for instance, is equivalent from 
 the thermal point of view to 1.66 grammes of sugar, 
 1.44 f albumen, or 0.73 of fat. These quantities 
 would be iset/jrxamif. 
 
 Experiment has not entirely decided for or against 
 this theory. However, the first tests have not been 
 very favourable to it. The researches of C. von 
 Noorden and his pupils, Stammreich and Miura, have 
 clearly and directly established that alcohol cannot 
 be substituted in a maintenance ration for an exactly 
 isodynamic quantity of carbohydrates. If the sub- 
 stitution is effected, a ration only just capable of 
 maintaining the organism in equilibrium becomes in- 
 sufficient. The animal decreases in weight. It loses 
 more nitrogenous matter than it can recover from 
 its diet, and this situation cannot be sustained for 
 long. On the other hand, the celebrated researches 
 of the American physiologist, A I water, would plead, 
 on the contrary, in favour of almost isodynamic sub- 
 stitution. Finally, Duclaux has shown that alcohol
 
 I3& LIFE AND DEATH. 
 
 is a real food, biothermogenic for certain vegetable 
 organisms. But urea is also a food for micrococcus 
 urece. It does not follow that it is a food for mam- 
 mals. We have not reached the solution yet adJiuc 
 sub judice. 
 
 Conclusion : The Energetic Character oj Food. To 
 sum up we have confined ourselves, in what has been 
 said, to the consideration of a single character of 
 food, and really the most essential, its energetic 
 character. Food must furnish energy to the organism, 
 and for that purpose it is decomposed and broken up 
 within it, and issues from it simplified. It is thus, 
 for instance, that the fats, which from the chemical 
 point of view are complicated molecular edifices, 
 escape in the form of carbonic acid and water. And 
 so it is with carbo-hydrates, starchy and sugary 
 substances. This is because these compounds 
 descend to a lower degree of complexity during their 
 passage through the organism, and by this drop, as it 
 were, they get rid of the chemical energy which they 
 contained in the potential state. Thermo-chemistry 
 enables us to deduce from the comparison of the 
 initial and final states the value of the energy 
 absorbed by the living being. This energetic, dynamo- 
 genie or thermogenic value, thus gives a measure of 
 the alimentary capacity of the substance. A gramme 
 of fat, for instance, gives to the organism a quantity 
 of energy equivalent to 9.4 Calories ; the thermo- 
 genic value of the albumenoids is 4.8 Calories. 
 The thermogenic or thermal value of carbohydrates 
 is less than 4.7 calories. This being so, we under- 
 stand why the animal is nourished by foods which 
 are products very high in the scale of chemical 
 complexity.
 
 ALIMENTARY ENERGETICS- 139 
 
 | 4. FOOD CONSIDERED EXCLUSIVELY AS 
 SOURCE OF HEAT. 
 
 We have seen that food is, in the first place, a 
 source of ckfmical emergj ; and, in the second place, 
 a source of vital cmfrgy finally, and consequently, a 
 source of thermal energy. It is this last point of 
 view which has exclusively struck the attention of 
 certain physiologists, and hence has arisen a peculiar 
 manner of conceiving the role of food. It consists in 
 looking on food as a source of thermal energy. 
 
 This conception is easily applied to warm-blooded 
 animals, but to them exclusively and this is where 
 it first fails. The animal is wanner than the environ- 
 ment in general It is constantly giving out heat to 
 it To repair this loss of heat it takes in food in 
 exact proportion to the loss it sustains, When it is a 
 question of cold-blooded vertebrates,, which live in 
 water and in most cases have an internal tem- 
 perature which is not distinguishable from that of 
 the environment, we see less clearly the thermal rdle 
 of food. It seems then that the production of heat 
 is an episodic phenomenon, not existing for itselt 
 
 However that may be, food is in the second pHace 
 a source of thermal energy for the organism. Can it 
 be said, inversely, that every substance which we in- 
 troduce into the economy, and which is there broken 
 up and gives off heat, is a food ? This is a moot 
 point. We dealt just now with purely thennogenic 
 foods. However, most physiologists are inclined to 
 give a positive answer. In their eyes the idea of food 
 cannot be considered apart from the fact of die pro- 
 duction of heat. They take the effect for the
 
 140 LIFE AND DEATH. 
 
 cause. To these physiologists everything ingested is 
 called food, if it gives off heat within the body. 
 
 To be heated by food is, indeed, an imperious 
 necessity for the higher animals. If this need be not 
 satisfied the functional activities become enervated ; 
 the animal falls into a state of torpor ; and if it is 
 capable of attenuated, of more or less latent, life it 
 sleeps in a state of hibernation ; but if it is not 
 capable of this, it dies. The warm-blooded animal 
 with a fixed temperature is so organized that this 
 constancy of temperature is necessary to the exercise 
 and to the conservation of life. To maintain this 
 indispensable temperature there must be a continual 
 supply of thermal energy. According to this, the 
 necessity of alimentation is confused with the 
 necessity of a supply of heat to cover the deficit 
 which is due to the inevitable cooling of the organism. 
 This is the point of view taken up by theorists, and 
 we cannot say that they have no right to do so. We 
 can only protest against the exaggeration of this 
 principle, and the subordination of the other roles of 
 food to this single role as a thermogen. It is the 
 magnitude of the thermal losses which, according to 
 these physiologists, determines the need for food, and 
 regulates the total value of the maintenance ration. 
 From the quantitative view it is approximately true. 
 From the qualitative point of view it is false. 
 
 Such is the theory opposed to the theory of 
 chemical and vital energy. It has on its side a large 
 number of experts, among whom are Rubner, Stoh- 
 mann, and von Noorden. It has been defended in an 
 article in the Dictionnaire de Physiologic by Ch. 
 Richet and Lapicque. They hold that thermogenesis 
 absolutely dominates the play of nutritive exchanges ;
 
 ALIMENTARY ENERGETICS. 141 
 
 and it is the need for the production of beat that 
 regulates the total demand for Calories which every 
 organism requires from its ration. It is not became 
 it produces too much heat that the organism gets rid 
 of it peripherally : it is rather because it inevitably 
 disperses it that it is adapted to produce it. 
 
 Rttbner's Experiments, This conception of the role 
 of alimentation is based on two arguments. The first 
 is furnished by Rnbner's last experiment (1893). A 
 dog in a calorimeter is kept alive for a rather long 
 period (two to twelve days) ; the quantity of heat 
 produced in this lapse of time is measured, and it is 
 compared with the heat afforded by the food. In all 
 cases the agreement is remarkable. But is it possible 
 that there should be no such agreement? Clearly no, 
 because there is a well-known regulating mechanism 
 which always exactly proportions the kisses and the 
 gains of heat to the necessity of maintaining the fixed 
 internal temperature. This first argument is, there- 
 fore, not conclusive. 
 
 The second argument is drawn from what has been 
 called the law of surfaces t clearly perceived by Reg- 
 nault and Reiset in their celebrated memoir in 1849, 
 formulated by Rubner in 1884. and beautifully 
 demonstrated by Ch. Richet. In comparing the 
 maintenance rations for subjects of very different 
 weights, placed under very different conditions, it is 
 found that the food always introduces the same num- 
 ber of Calories for the same extent of skin 1>, for 
 the same cooling surface. The numerical data 
 collected by EL Vbit show that, under identical con- 
 ditions, warm-blooded animals daily expend the same 
 quantity of heat per unit of surface namely, 1.036 
 Calories per square yard. The average ration intro-
 
 142 LIFE AND DEATH. 
 
 duces exactly the amount of food which gives off 
 sensibly this number of Calories. Now, this is an 
 interesting fact, but, like the preceding, it has no 
 demonstrative force. 
 
 Objections. The Limits of Isodynamism. On the 
 contrary, there are serious objections. The thermal 
 value of the nutritive principles only represents one 
 feature of their physiological role. In fact, animals 
 and man are capable of extracting the same profit 
 and the same results from rations in which one of the 
 foods is replaced by an isodynamic proportion of the 
 other two that is to say, a proportion developing the 
 same quantity of heat. But this substitution has very 
 narrow limits. Isodynamism that is to say, the 
 faculty that food has of supplying pro rata its thermal 
 values is limited all round by exceptions. In the 
 first place, there are a few nitrogenous foods that no 
 other nutritive principle can supply; and besides, be- 
 yond this minimum, when the supply takes place, it is 
 not perfect. Lying between the albuminoids and the 
 carbohydrates relatively to the fats, it is not between 
 these two categories relatively to nitrogenous sub- 
 stances. If the thermal power of food were the only 
 thing that had to be considered in it, the isodynamic 
 supply would not fail in a whole category of principles 
 such as alcohol, glycerine, and the fatty acids. Finally, 
 if the thermal power of a food is the sole measure of 
 its physiological utility, we are compelled to ask why 
 a dose of food may not be replaced by a dose of heat. 
 External warming might take the place of the internal 
 warming given by food. We might be ambitious 
 enough to substitute for rations of sugar and fat an 
 isodynamic quantity of heat-giving coal, and so 
 nourish the man by suitably warming his room. In
 
 ALIMENTARY ENERGETICS. 143 
 
 reality, food has many other offices to fulfil than 
 that of warming the body and of giving it energy 
 that is to say, of providing for the functioual activity 
 of the living machine. It must also serve to provide 
 for wear and tear. The organism needs a suitable 
 quantity of certain fixed principles, organic and 
 mineral These substances are evidently intended to 
 replace those which have been involved in the cycle 
 of matter, and to reconstitute the organic material. 
 To these materials we may give the name of histo- 
 genetic foods (repairing the tissues), or of plastic 
 foods. 
 
 5. THE PLASTIC R6LE OF FOOD. 
 
 Opinions of the Early Physiologists. It is from this 
 point of view that the ancients regarded the role of 
 alimentation. Hippocrates, Aristotle, and Galen 
 believed in the existence of a unique nutritive sub- 
 stance, existing in all the infinitely different bodies 
 that man and the animals utilize for their nourish- 
 ment. It was Lavoisier who first had the idea of a 
 dynamogenic or thermal role of foods. Finally, the 
 general view of these two species of attributes and 
 their marked distinction is due to J. Liebig, who 
 called them//<tt//V: and dynamogenic foods. In addition 
 he thought that the same substance should accumulate 
 the same attributes, and that this was the case with 
 the albuminoid foods, which were at once plastic and 
 dynamogenic. 
 
 Preponderance of Nitrogenous Foods. Magendie, in 
 1836, was the pioneer who introduced in this inter- 
 minable list of foods the first simple division. He 
 divided them into proteid substances, still called
 
 144 LIFE AND DEATH. 
 
 albuminoids, nitrogenous, quaternary, and ternary 
 substances. Proteid substances are capable of main- 
 taining life. Hence the preponderant importance 
 given by the eminent physiologist to this order of 
 foods. These results have since been verified. Pfliager, 
 of Bonn, gave a very convincing proof of this a few 
 years ago. He fed a dog, made it work, and finally 
 fattened it, by giving it nothing at all to eat but meat 
 from which had been extracted, as thoroughly as 
 possible, every other substance. 1 The same experiment 
 showed that the organism can manufacture fats and 
 carbo-hydrates at the expense of the nitrogenous food, 
 when it does not find them ready formed in the ration. 
 The albumen will suffice for all the needs of energy and 
 and matter. To sum up, there is no necessary fat, no 
 carbohydrate is necessary; albuminoids alone are in- 
 dispensable. Theoretically, the animal and man alike 
 could maintain life by the exclusive use of proteid 
 food; but, practically, this is not possible for man, 
 because of the enormous amount of meat which 
 would have to be used (3 kilogrammes a day). 
 
 Ordinary alimentation comprises a mixture of 
 three orders of substances, and to this mixture 
 albumen brings the plastic element materially neces- 
 sary for the reparation of the organism ; it also is 
 the source of energy. The two other varieties only 
 bring energy. In this mixed regimen the quantity 
 of albumen must never descend below a certain 
 minimum. The efforts of physiologists of late years 
 have tended to fix with precision this minimum 
 ration of albuminoids or as we may briefly put it, 
 
 1 It is not certain, however, that all the precautions taken 
 have the desired result. You cannot entirely deprive meat of its 
 carbohydrates.
 
 ALIMENTARY ENERGETICS. 145 
 
 of albumen below which the organism would perish. 
 Voit had found 118 grammes of albumen necessary 
 for the average adult man weighing 70 kilos. This 
 figure is certainly too high. The Japanese doctors, 
 Mori, TsuboT, and Murato, have shown that a con- 
 siderable portion of the population of Japan is 
 content with a diet much poorer in nitrogen, and 
 suffers no inconvenience. The Abyssinians, according 
 to Lapicque, ingest, on the average, only 67 
 grammes of albumen per day. A Scandinavian physi- 
 ologist, Siven, experimenting on himself, found that 
 he could reduce the ration of albumen necessary to 
 the maintenance and equilibrium of the organism to 
 the lowest figures which have been yet reached 
 namely, from 35 to 46 grammes a day. These 
 experiments, however, must be confirmed and inter- 
 preted. Besides, it is important to point out that the 
 most advantageous ration of albumen requires to be 
 a good deal above the strictly sufficient quantity. 
 
 It only remains to refer to several other recent 
 researches. The most important of many are those 
 published by M. Chauveau, on the reciprocal trans- 
 formation of the immediate principles in the organism 
 according to the conditions of its functioning and 
 the circumstances of its activity. To deal with 
 these researches with as much detail as they deserve, 
 we must study the physiology of muscular contraction 
 and of movement that is to say, of muscular 
 energetics.
 
 BOOK III. 
 
 THE CHARACTERS COMMON TO LIVING BEINGS. 
 
 Chapter I. Summary: The doctrine of vital unity. Chapter II. 
 The morphological unity of living beings. Chapter III. 
 The chemical unity of living beings. Chapter IV. The 
 mutability of living beings. Chapter V. The specific 
 form, its acquisition, and reparation. Chapter VI. Nutri- 
 tion. 
 
 CHAPTER I. 
 
 THE DOCTRINE OF VITAL UNITY. 
 
 Phenomena common to all living beings Theory of vital 
 duality Unity in the formation of immediate principles 
 Unity in the digestive acts The common vital fund. 
 
 WHEN we ask the various philosophical schools what 
 life is, some show us a chemical retort, and others 
 show us a soul. Whether vitalists or of the mechanical 
 school, these are the adversaries who since philosophy 
 began have vainly contested the possession of the 
 secret of life. We need not concern ourselves with this 
 eternal quarrel. We need not ask Pythagoras, Plato, 
 Aristotle, Hippocrates, Paracelsus, Van Helmont, 
 and Stahl what idea they formed of the vital 
 principle ; nor need we probe to the depths the 
 ideas of living nature held by Epicurus, Democritus, 
 I 4 6
 
 THE DOCTRINE OF VITAL UNITY. 147 
 
 Boerhaave, Willis, and Lamettrie ; nor need we 
 apply to the iatrocnechanicians nor to the chemists. 
 We may do better than that. We may ask nature 
 itself. 
 
 Phenomena Common to Living Beings. Nature 
 shows us an infinite number of beings, animal or 
 vegetable, described in ordinary language as Ihing 
 beings. This language implicitly assumes something 
 common to them all, a universal manner of being 
 which belongs to them without distinction, without 
 regard to differences of species, types, or kingdoms. 
 On the other hand, anatomical analysis teaches us 
 that animated beings and plants may be divided into 
 parts ever decreasing in complexity, of which the 
 last and the simplest is the anatomical element, the 
 #, the microscopic organic unit which, too, is alive- 
 Common opinion suspects that all these beings, 
 whether entire as in the case of animal and vege- 
 table individuals, or fragmentary as in the case of 
 cellular elements, have the same manner of being, 
 and present the same body of common characteristics 
 which rightly gives them this unmistakable title of 
 living beings. Life then essentially would be this 
 manner of being, common to aninmls, vegetables, and 
 their elements. To seize in isolation these common, 
 necessary, and permanent features, and then to 
 synthetize them into a whole, will be the really 
 scientific method of defining; life, and of explaining 
 its nature. 
 
 And here then immediately arises a fundamental 
 question which gives one pause, a question of fact 
 which must be solved before we can go further. 
 Is there really a common manner of being in all 
 these tilings ? Are animal life, vegetable life, and the
 
 148 LIFE AND DEATH. 
 
 life of the elements or elementary life, all the same? 
 Is there a sum total of characteristics which may 
 define life in general ? 
 
 The physiologists, following in the steps of Claude 
 Bernard, respond in the affirmative. They accept as 
 valid and convincing the proof given of this vital 
 community by the illustrious experimentalist. How- 
 ever, there are some rare exceptions to this universal 
 assent. In this concert of approval thsre is at least 
 one discordant voice, that of M. F. Le Dantec. 1 
 
 1 M. Le Dantec, of whose philosophical and rigorously 
 systematic mind I have the highest opinion, has laid down a 
 new conception of life, the essential basis of which is this very 
 distinction between elementary life and ordinary life; between 
 the life of the elements or of the beings formed from a single 
 cell, protophytes and protozoa, and the life of ordinary animals 
 and plants, which are multicellular complexes, and for that 
 reason called metazoa and metaphytes. 
 
 Further, in the elementary life peculiar to monocellular 
 beings (protozoa and cellular elements), M. Le Dantec dis- 
 tinguishes three manners of being: The first condition, which 
 is elementary life manifested in all its perfection, cellular 
 health ; the second condition is deteriorated elementary life, 
 cellular disease; and the third condition, which is latent life. 
 I should say at once that in so far as the fundamental dis- 
 tinction of the phenomena of elementary life and those of the 
 general life of animals and ordinary plants, metazoa or meta- 
 phytes, is concerned, we find it neither justified nor useful. 
 And further, manifested elementary life, as M. Le Dantec 
 understands it, would only belong to a small number of 
 elementary Sitingstot the protozoa, starting with the infusoria, 
 are not among the number and to a still smaller number of 
 anatomical elements, since among the vertebrates we recognize 
 as almost the only elements satisfying it, the ovule, and perhaps 
 the leucocyte. Physiologists, therefore, do not agree with 
 M. Le Dantec as to the utility of adding one condition more to 
 those we all admit namely, manifested animal life and latent 
 life.
 
 THE DOCTRINE OF VITAL UNITY. 149 
 
 The Doctrine of the Vital Duality of Animals and 
 Plants. There are, therefore, biologists who, in the 
 domain of theory and in virtue of more or less well- 
 founded conceptions or interpretations, separate 
 elementary life from other vital forms, and thus break 
 the bond of vital unity proclaimed by Claude Bernard. 
 This monistic doctrine at the outset met with other 
 opponents, and that, too, in the domain of facts. 
 But it triumphed over them and became established. 
 We have to deal with scientists like J. B. Dumas and 
 Boussingault, who drew a dividing line between 
 animal life and vegetable life. 
 
 But let us in a few words recall to the reader this 
 victorious struggle of the monistic doctrine against 
 the dualism of the two kingdoms. If we consider an 
 animal in action, said the champions of vital dualism, 
 we agree that it feels, moves, breathes, digests, and 
 finally, that it destroys by a real operation of chemical 
 analysis the materials afforded to it by its ambient 
 world. It is in these phenomena that are manifested 
 its activity, its life. Now, added the dualists, plants 
 do not feel, do not move, do not breathe, and do not 
 digest. They build up from immediate principles, 
 by an operation of chemical synthesis, the materials 
 they borrow from the soil which bears them, or from 
 the atmosphere which surrounds them. There is, 
 therefore, nothing in common between the repre- 
 sentatives of the two kingdoms if we confine ourselves 
 to the examination of the actual phenomena which 
 take place in them. To find a resemblance between 
 the animal and the vegetable, said the dualists, we 
 must set aside what they do, for they do different, or 
 even contrary things. We must consider whence 
 they come and what they become. Both originate
 
 150 LIFE AND DEATH. 
 
 in organisms similar to themselves. They grow, 
 evolve, and generate as they themselves weie 
 generated. In other words, while their acts separate 
 plants from animals, their mode of origin and 
 evolution alone bring them together. Such analogies 
 are of no slight importance ; but they were neutralized 
 by their dissimilarities, which were exaggerated by 
 f the dualistic school. 
 
 It is clear that the word life would lose all actual 
 significance to those who would reduce it to the 
 faculty of evolution, and who would separate all its 
 real manifestations in animated beings and in plants. 
 If there are two lives, the one animal and the other 
 vegetable, there are no more ; or, what comes to the 
 same thing, there is an infinite number of lives which 
 have nothing in common but the name, or at most, 
 the possession of some secondary characteristics. 
 There are as many of them as there are different 
 beings, for each has its own particular evolution. 
 Here the specific is the negation of the general and 
 it destroys it instead of being subordinate to it. The 
 principle of life becomes for each being something as 
 individual as its own evolution. And this, if we 
 think it out, is how the philosophers look at life, and 
 it is the real reason of their disagreement with the 
 physiological school. 
 
 - Proof of the Monistic TJieory, On the other hand, 
 under the disguise of living forms, the physiologist 
 recognizes the existence of an identical basis. His 
 trained ear marks amid the overcharged in- 
 strumentation of the vital work the recognizable 
 undertones of a constant theme. It was the work of 
 Claude Bernard to bring this common basis to 
 light. He shows that plants live as animals do,
 
 THE DOCTRINE OF VITAL UNITY. 151 
 
 that they breathe, digest, have sensory reactions, 
 move essentially like animals, destroy and build up 
 in the same manner the immediate chemical prin- 
 ciples. For that purpose it was necessary to pass in 
 review, examining them from their foundation and 
 distinguishing the essential from the secondary, the 
 different vital manifestations digestion, respiration, 
 sensibility, motility, and nutrition. This is what 
 Claude Bernard did in his work Sur les Phenomenes 
 de la vie communs attx animaux et aux plantes. We 
 need only to sketch in broad outline the character- 
 istic features of his lengthy demonstration. 
 
 Unity in tJte Formation of Immediate Chemical 
 Principles. The first and most important of the 
 differences pointed out between the life of animals 
 and that of plants was relative to the formation of 
 immediate principles. On this ground, indeed, vital 
 dualism raised its fortress. The animal kingdom 
 was considered in its totality as the parasite of the 
 vegetable kingdom. To J. B. Dumas, animals, 
 whatever they may be, make neither fat nor any 
 elementary organic matter ; they borrow all their 
 foods, whether they be sugars or starches, fats or 
 nitrogenous substances, from the vegetable kingdom. 
 About the year 1843 the researches of the chemists, 
 and of Payen in particular, succeeded in proving the 
 presence, almost constant, of fatty matters in vege- 
 tables ; and, further, these matters existed there in 
 proportions more than sufficient to explain how 
 the beast which fed upon them was fattened. The 
 chemists attributed to nature as much practical sense 
 as they themselves possessed ; and since the hay and 
 the grass of the ration brought fat ready made to the 
 horse, the cow, and the sheep, they declared that the 
 
 ii
 
 152 LIFE AND DEATH. 
 
 animal organism had nothing whatever to do but to 
 put this food into the tissues, or to arrange for it to 
 pass into the milk. But nature is not so wise and 
 economical as was supposed at the Academic des 
 Sciences. After a memorable debate, in which 
 Dumas, Boussingault, Payen, Liebig, Persoz, Chossat, 
 Milne-Edwards, and Flourens took part, and, later on, 
 Berthelot and Claude Bernard, it was agreed that 
 the animal does not grow fat from the fatty food 
 which is supplied it, and that it makes its own fat 
 just as the vegetable does, but in another manner. 
 In the same way sugar, the normal constituent sub- 
 stance necessary for the nutrition of animals and 
 plants, instead of being a vegetable product passing 
 by alimentation from the herbivorous animals and 
 thence to the carnivorous, is manufactured by the 
 animal itself. Generally speaking, immediate prin- 
 ciples have an equal claim to existence in the two 
 kingdoms. Both form and destroy the substances 
 indispensable to life. 
 
 Here, then, one of the barriers between animal life 
 and vegetable life is overthrown and destroyed. 
 
 Unity of Digestive Acts in Animals and Plants. 
 Similarly, another barrier falls if we show that 
 digestion, long considered the exclusive function of 
 animals, and, in particular, of the higher animals, is 
 in reality universal. 
 
 Cuvier pointed out the absence of a digestive 
 apparatus as a very general and distinctive char- 
 acteristic of plants. But the absence of a digestive 
 apparatus does not necessarily imply the absence of 
 digestion. The essential act of digestion is indepen- 
 dent of the infinite variety of the organs, just as a 
 reaction is independent of the form of the vessel in
 
 THE DOCTRINE OF VITAL UNITY. 153 
 
 which it takes place. It is, in fact, a chemical 
 transformation of an alimentary substance. This 
 transformation may be realized outside the organism, 
 in ^'itr0, just as it can in the living being without 
 masticating organs, without an intestinal apparatus, 
 without glands, in a vessel placed in a stove, simply 
 by means of a few soluble ferments pepsine, trypsine, 
 amylolytic diastases. 
 
 All alimentary- substances, whether taken from 
 without or borrowed from the reserves accumulated 
 in the internal stores of the organism, must undergo 
 preparation. This preparation is digestion. Diges- 
 tion is the prologue of nutrition. It is over when the 
 reparative substance, whether food or reserve-stuff, 
 is brought into a state enabling it to pass into the 
 blood, and to be utilized by the organism. 
 
 The Identity of Categories of Foods in the Two 
 Kingdoms. Now the alimentary substances are the 
 same in the two kingdoms, and so is their digestive 
 preparation. Alimentary materials are of four 
 kinds : albuminoid, starchy, fatty, and sugary sub- 
 stances. The animal takes them from without 
 (food properly so-called), or from within freserve- 
 stufF). Man obtains starch, for instance, from different 
 farinaceous dishes. It may, however, equally well 
 be borrowed from the reserve of flour that we cam- 
 within us in our liver, which is a veritable granary, 
 full of floury substance, glycogen. And so it is with 
 vegetables. The potato has its store of flour in its 
 tuber just as the animal has in its liver. The grain 
 which is about to germinate has it in reserve-stuff in 
 its cotyledons, or in its albumen. The bud which is 
 about to develop into a tree or a flower carries it at 
 its base
 
 154 LIFE AND DEATH. 
 
 The same conclusions are true for another class 
 of substances, the sugars. They may be a food taken 
 from without, or a reserve deposited in the tissues. 
 The animal takes from without, in fruits for instance, 
 the ordinary sugar which pleases its taste. Beetroot, 
 when flowering and fructifying, draws this substance 
 from its roots in which stores have been amassed. 
 The sugar cane when running to seed takes the 
 sugar from the stores which it possesses in its cane. 
 Brewer's yeast, the sacckaromyces cerevisits, the agent 
 of alcoholic fermentation, finds this same substance in 
 the sugary juices favourable to its development. 
 
 In the same way, identically fatty substances, 
 either in the form of food or of reserve-stuff, serve 
 for nutrition to animals and vegetables ; and that is 
 again true of the substances of the fourth class, 
 albuminoids, identical in the two kingdoms, foods or 
 reserve-stuff, equally utilizable in both after digestion. 
 
 Identity of the Digestive Agents and Mechanisms in 
 Plants and Animals. Now, the results of contem- 
 porary research have been to establish a surprising 
 resemblance in the modifications experienced by these 
 foods, or reserve stuffs, in animals and plants; and 
 even resemblances in the agents which realize them, 
 and in the mechanisms by which they are performed. 
 There is a real unity. The flour accumulated in the 
 tuber of the potato is liquefied and digested on the 
 appearance of the buds or of the flower, just as the 
 starch of the liver or the alimentary flour is digested 
 by the animal. The fatty matter which is stored up 
 in the oleaginous grain is digested at the moment of 
 germination, just as the fat during a meal is digested 
 in the animal's intestine. As the beetroot begins to 
 run to seed, the root gives up part of its store of
 
 THE DOCTRINE OF VITAL UNITY. 155 
 
 sugar, and this reserve stuff is distributed throughout 
 the stalk after having been digested, exactly as would 
 have been the case in the digestive canal of man. 
 
 Vegetables, then, really digest. The four classes of 
 substances mentioned above are really digested in 
 order to pass from their actual form, a form unsuitable 
 for interstitial exchanges, to another form suitable for 
 nutrition. As there are four kinds of foods, so there 
 are four kinds of digestions, four kinds of ferment- 
 producing agents amylolytic, 1 proteolytic, 2 sacchar- 
 ine, and lipasic 3 diastases, identical in the animal 
 and the plant Identity of ferments implies identity 
 of digestions. Going down to the very basis of 
 things, the digestive act is nothing but the action of 
 this ferment This is the crux of the whole question. 
 All else is only difference in scene, varying in the 
 means of execution and in the accessories. The 
 difference arises from the stage on which it takes 
 place, but the piece which is being played is the 
 same, and the actors are the same, and so is the 
 action of the play. 
 
 "~ This identity between animal and vegetable life is 
 found in the phenomena of respiration and of motility. 
 The limits of this book do not allow of our entering 
 into the details of facts. Besides, the facts are well 
 known, and may be found in any treatise on general 
 physiology. This science, therefore, enables us to 
 perceive the impn^jng unity of life in its essential 
 manifestations. 
 
 1 Amylolytic ferments change starch and glycogen (atnyloses) 
 into sugar. TR. 
 
 2 Proteolytic ferments change proteids into peptones and 
 proteoses. TR. 
 
 3 The enzyme known as lipase splits the fat or oil in germ- 
 inating seeds into a fatty acid and glycerine. TR.
 
 I5& LIFE AND DEATH. 
 
 The community of the phenomena of vitality in 
 animals and plants being thus placed beyond a doubt, 
 we must now discover the reason why. This reason 
 is to be found in their anatomical and in their 
 chemical unity. The fundamental phenomena are 
 common because the composition is common, and 
 because the universal anatomical basis, the cell, 
 possesses in all cases a sum total of identical 
 properties. 
 
 If we appeal to physiology for the characteristics 
 common to living beings, it will generally give us the 
 following: A structure or organization; a certain 
 chemical composition which is that of living matter ; 
 a specific form ; an evolution which in the earliest 
 stage occasions the being to grow and develop until 
 it is divided, and which in the highest stage includes 
 one or more evolutive cycles with growth, the adult 
 stage, senility, and death ; a property of increase or 
 nutrition, with its consequence namely, a relation of 
 material exchanges with the ambient medium ; and 
 finally, a property of reproduction. It is important 
 to pass them rapidly in review.
 
 CHAPTER II. 
 
 MORPHOLOGICAL UNITY OF LIVING BEINGS. 
 
 i. The cellular theory. First period: division of the organism 
 >? 2. Second period: division of the cell Cytoplasm 
 The nucleus 3. Physical constitution of living matter 
 The micellar theory 4. Individuality of complex beings 
 The law of the constitution of organisms. 
 
 THE first characteristic of the living beings is 
 organization. By that we mean that they have a 
 structure; that they are complex bodies formed of 
 smaller aliquot parts and grouped according to a 
 certain disposition. The most simple elementary 
 being is not yet homogeneous. It is heterogeneous. 
 It is organized. The least complex protoplasms, 
 that of bacteria, for example, still possess a 
 physical structure; Kunstler distinguishes in them 
 two non-miscible substances, presenting an alveolar 
 organization. Thus animals and plants present an 
 organization, and it is sensibly constant from one end 
 to the other of the scale of beings. There is a 
 morphological unity. 
 
 i. THE CELLULAR THEORY. FIRST PERIOD: 
 DIVISION OF THE ORGANISM INTO CELLS. 
 
 Cellular T/ieory. First Period. Morphological 
 unity results from the existence of a universal 
 ID?
 
 '15$ 'LIFE AND DEATH. 
 
 anatomical basis, the cell. The cellular theory sums 
 up the teaching of general anatomy or histology. 
 
 At the beginning of the nineteenth century anatomy 
 was following a routine dating from ancient times. 
 It divided animal and vegetable machines into units 
 in descending order, first into different forms of 
 apparatus (circulatory, respiratory, digestive, etc.); 
 then the apparatus into organs examined one by one, 
 figuring and describing each of them from every 
 point of view with scrupulous accuracy and untiring 
 patience. If we think of the duration of these 
 researches the Iliad, as Malgaigne says, already 
 containing the elements of a very fine regional 
 anatomy and especially of the powerful impulse 
 they received in the seventeenth and eighteenth 
 centuries, we shall understand the illusion of those 
 who, in the days of X. Bichat, could fancy that the 
 task of anatomy was almost ended. 
 
 As a matter of fact this task was barely begun, for 
 nothing was known of the intimate structure of the 
 organs. X. Bichat accomplished a revolution when 
 he decomposed the living body into tissues. His 
 successors, advancing a step in the analysis, dis- 
 sociated the tissues into elements. These elements, 
 which one would have thought were infinitely varied, 
 were reduced in their turn to one common prototype, 
 the cell. 
 
 The living body, disaggregated by the histologist, 
 resolves under the microscope into a dust, every grain 
 of which is a cell. A cell is an anatomical element 
 the constitution of which is the same from one part 
 to the other of the same being, and from one being to 
 another; and its dimensions, which are sensibly 
 constant throughout the whole of the living world,
 
 MORPHOLOGICAL UNITY OF LIVING BEINGS. 159 
 
 have an average diameter of several thousandths of 
 a millimetre />., of several microns. This element, 
 the cell, is a real organ. It is smaller, no doubt, than 
 those described by the ancient anatomists, but it is not 
 less complex. Its complexity is only revealed later. 
 It is an organic unit. Its form varies from one 
 element to another. Its substance is a semi-fluid 
 mass, a mixture of different albuminoids. In the 
 mean value of its dimensions, so carefully measured 
 exceptis excipiendis we have a condition the signi- 
 ficance of which has not yet been discovered, but 
 which may be of great value in the explanation of its 
 peculiar activities. 
 
 Such is the result to which have converged the re- 
 searches of the biologists who have examined plants 
 or the lower animals, as well as of the anatomists who 
 have been more especially occupied with the verte- 
 brates and with man. All their researches have 
 brought them to the same conclusion the cellular 
 theory. Either living beings are composed of a single 
 cell as is the case with the microscopic animals called 
 protozoa, and the microscopic vegetables called proto- 
 phytes or, they are cellular complexes, metasoa or 
 nutaphytes that is to say, associations of these 
 microscopic organic units which are called cells. 
 
 The Law of tJie Composition of Organisms. The 
 law of the composition of organisms was discovered 
 in 1838 by Schleiden and Schwann. From that time 
 up to 1875 it niay be said that micrographers have 
 spent their time in examining every organ and every 
 tissue, muscular, glandular, conjunctive, nervous, etc., 
 and in showing that in spite of their varieties of 
 aspect and form, of the complexity of structures due 
 to cohesion and fusion, they all resolve into the com-
 
 l6o LIFE AND DEATH. 
 
 mon element, the cell. Contemporary anatomists, 
 Koelliker, Max Schultze, and Ranvier, have thus 
 established the generality of the cellular constitution, 
 while zoologists and botanists confirm the same law 
 for all animals and vegetables, and exhibit them all 
 as either unicellular or multicellular. 
 
 The Cellular Origin of Complex Beings. At the 
 same time embryogenic researches showed that all 
 beings spring from a corpuscle of the same type. 
 Going back in the history of their development to the 
 most remote period, we find a cell of very constant 
 constitution namely, the ovule. This truth may be 
 expressed by changing a word in Harvey's celebrated 
 aphorism omne vivum ex ovo ; we now say omne 
 vivum e cellula. The myriads of differentiated ana- 
 tomical elements whose association forms complex 
 beings are the posterity of a cell, of the primordial 
 ovule, unless they are the posterity of another equiva- 
 lent cell. The second task of histology in the latter 
 half of the nineteenth century consisted in following 
 up the filiation of each anatomical element from the 
 cell-egg to its state of complete development. 
 
 The whole cellular theory is contained in the 
 two following statements, which establish the mor- 
 Dhological unity of living beings: Everything is a 
 ?ell, everything' comes from an initial cell; the cell 
 aeing defined as a mass of substance, protoplasm or 
 protoplasms, of an average diameter of a few microns. 
 
 2. THE SECOND PERIOD : THE DIVISION OF 
 THE CELL. 
 
 Second Period : Constitution of the >//. This was, 
 however, only the first phase in the analytical study
 
 MORPHOLOGICAL UNITY OF LIVING BEINGS. l6l 
 
 of the living being. A second period began in 
 1873 with the researches of Strassburger, Biitschli, 
 Flemming, Kuppfer, Fromann, Heitzmann, Balbiani, 
 Guignard, Kunstler, etc. These observers in their 
 turn submitted this anatomical, this infinitely small 
 cellular microcosm, to the same penetrating dissection 
 their predecessors had applied to the whole organ- 
 ism. They brought us down one degree lower into 
 the abyss of the infinitely small. And as Pascal, 
 losing himself in these wonders of the imperceptible, 
 w in the body of the mite which is only a point, 
 " parts incomparably smaller, legs with joints, veins in 
 the legs, blood in the veins, humours in the blood, 
 drops in the humours, vapours in these drops," so 
 contemporary biologists have shown in the epitome 
 of organism called a cell, an edifice which itself is 
 marvellously complex. 
 
 Tlie Cytoplasm. The observers named above re- 
 vealed to us the extreme complexity of this organic 
 unit Their researches have shown us the structure 
 of the two parts of which it is composed the cellular 
 protoplasm and the nucleus. They have determined 
 the part played by each in genetic multiplication. 
 They have shown that the protoplasm which forms the 
 body of the cell is not homogeneous, as was at first 
 supposed. The idea which was mooted later, that 
 this protoplasm was formed, to use Sachs' words, of a 
 kind of " protoplasmic mud," i.e., of a dust consisting 
 of grains and granules connected by a liquid, is no 
 longer accurate. There is a much simpler view of the 
 case. According to Leydig and his pupils, we must 
 compare the protoplasm to a sponge in the meshes of 
 which is lodged a fluid, transparent, hyaline substance, 
 a kind of cellular juice, hyaloplasm. From the
 
 l62 LIFE AND DEATH. 
 
 chemical point of view this cellular juice is a mixture 
 of very different materials, albumens, globulins, carbo- 
 hydrates, and fats, elaborated by the cell itself. It is 
 a product of vital activity ; it is not yet the seat of 
 this activity. The living matter has taken refuge in 
 the spongy tissue itself, in the spongioplasm. 
 
 According to other histologists, the comparison of 
 protoplasm to a spongy mass does not give the 
 most exact idea, and, in particular, it does not furnish 
 the most general idea. It would be far better to say 
 that the protoplasm possesses the structure of foam 
 or lather. As was seen by Kunstler in 1880, a com- 
 parison with some familiar objects gives the best idea. 
 Nothing could be more like protoplasm physically 
 than the culinary preparation known as sauce mayon- 
 naise^ made with the aid of oil and a liquid with 
 which oil does not mix. Emulsions of this kind were 
 made artificially by Butschli. He noted that these 
 preparations mimicked all the aspects of cellular 
 protoplasm. Thus, in the living cell there is a 
 mixture of two liquids, non-miscible and of unequal 
 fluidity. This mixture gives rise to the formation of 
 little cells. The more consistent substance forms 
 their supporting framework (Leydig's spongioplasm), 
 while the other, which is more fluid, fills its interior 
 (hyaloplasm). 
 
 However that may be, whether the primitive 
 organization of the cellular protoplasm be that of a 
 sponge, as is asserted by Leydig, or that of a sauce 
 mayonnaise^ as is claimed by Butschli and Kunstler, 
 the complexity does not rest there. Further recourse 
 must be made to analysis. Just as the tissue of a 
 sponge, when torn, shows the fibres which constitute 
 it, so the spongioplasm, the parietal substance, is
 
 MORPHOLOGICAL UNITY OF LIVING BEINGS. 163 
 
 exhibited as formed of a tangle of fibrils, or better 
 still, of filaments or ribbons (in Greek, mitome\ which 
 are called chromatic filament* , because they are deeply 
 stained when the cell is plunged into aniline dye. In 
 each of these filaments, the substance of which is 
 called chromatin, the devices of microscopic examina- 
 tion enable us to discover a series of granulations like 
 beads on a string, the microsonus or bioblasts, con- 
 nected one with the other by a sort of cement, 
 Schwartz's linin, which is a kind of nuclein. 
 
 And let us add, to complete this summary of the 
 constitution of cellular protoplasm, that it presents, at 
 any rate at a certain moment, a remarkable organ, 
 the centrosome, which plays an important part in 
 cellular division. Its pre-existence is not certain. 
 Some writers make it issue from the nucleus. At the 
 moment of cellular division it appears like a com- 
 pressed mass of granulations, which may be deeply 
 stained. Around it is seen a clear unstainable zone, 
 called the attraction-sphere ; and finally, beyond this 
 is a crown of striae, which diverge like the rays of a 
 halo />., the aster. In conclusion, there are yet in 
 the cellular body three kinds of non-essential bodies : 
 the vacuoles, the leucites, and various inclusions. The 
 vacuoles are cavities, some inert, some contractile ; the 
 leucites are organs for the manufacture of particular 
 substances ; the inclusions are the manufactured pro- 
 ducts, or wastes. 
 
 TJie Nucleus. Every cell capable of living, 
 growing, and multiplying, possesses a nucleus of 
 constitution very analogous to the cellular mass 
 which surrounds it The anatomical elements in 
 which no nucleus is found, such as the red globules 
 of blood in adult mammals, are bodies which are
 
 164 LIFE AND DEATH. 
 
 certain, sooner or later, to disappear. There is there- 
 fore no real cell without a nucleus, any more than 
 there is a nucleus without a cell. The exceptions to 
 this law are only apparent. Histologists have 
 examined them one by' one, and have shown their 
 purely specious character. We may therefore lay 
 aside, subject to possible appeal from this decision, 
 organisms such as Haeckel's monera and the problem 
 of finding out if bacteria really have a nucleus. The 
 very great, if not the absolute generality of the 
 nuclear body, must be admitted. 
 
 It hence follows that there is a nuclear protoplasm 
 and a nuclear juice, just as we have seen that there is a 
 protoplasm and a cellular juice. What was just said of 
 the one may now be repeated of the other, and perhaps 
 with even more emphasis. The nuclear protoplasm 
 is a filamentary mass sometimes formed of a single 
 mitome or cord, folded over on itself and capable of 
 being unrolled. The mitome in its turn is a string 
 of microsomes united by the cement of the linin. 
 These are the same constituent elements as before, 
 and the language of science distinguishes them one 
 from the other by a prefix to their name of the words 
 cyto or karyo, which in Greek signify cell and nucleus, 
 according as they belong to one or the other of these 
 organs. These are mere matters of nomenclature, 
 but we know that in the descriptive sciences such 
 matters are not of minor importance. 
 
 We have just indicated that in a state of repose, 
 that is to say, under ordinary conditions, the structure 
 of a nucleus reproduces clearly the structure of the 
 cellular protoplasm which surrounds it. The nuclear 
 essence is best separated from the spongioplasm. 
 It takes more clearly the form of a filamentary
 
 MORPHOLOGICAL UXTTT OF LIVING BEDCGS. 165 
 
 thread, and die filaments diemselves (mitome) show 
 very duck chromatic granulations, or midosomes, 
 connected by die linin. 
 
 At die moment of reproduction of die cell these 
 granulations blend into a stainable Jiearti which 
 surrounds die filaments, and die latter dispose diem- 
 selves so as to form a single thread. This chromatic 
 filament, which has now become a single thread, is 
 shortened as it thickens spircmf\ / it is then cut into 
 segments, twelve or twenty-four in die case of animak 
 and a larger number in die case of plants. These 
 are chromosomes, or xmdeaar sfgmaUs, or chromatic 
 loops. Their part is a very important one. They 
 are constant in number and permanent during die 
 whole of die life of die cell Let us add tiiat die 
 nucleus still contains accessory elements (nndeoli}, 
 
 The Role of the Nmdems. Experiment has shown 
 tiiat die nucleus presides over die nutrition, die 
 growtix, and die conservation of die celL If, following 
 die example of Balbiani Gruber, Xussbaum, and 
 W. Ronx of Leipzig, we cut into two a cell without 
 injuring die nucleus, die fragment which is denuded 
 of die nucleus continues to perform its functions for 
 some time in die ordinary manner, and in some 
 **ramn* in virtue of its former impulse. It then 
 declines and dies. On die contrary, die fragment 
 provided with die nucleus repairs its 'wound, is 
 reconstituted and continues to live. Thus die nucleus 
 takes a very remarkable part in the reproduction of 
 die cell, but it is still a matter of uncertainty whether 
 its role is here subordinated to tiiat of die cellular 
 body, or if it is pre-eminent. However that may be, 
 it follows from diis experiment tiiat die nucleus 
 presents all the characteristics of a vigorous vitality,
 
 l66 LIFE AND DEATH. 
 
 and that it is in its protoplasm that the chemists 
 should be able to find the compounds, the special 
 albuminoids, which, par excellence, form living matter. 
 
 3. THE PHYSICAL CONSTITUTION OF LIVING 
 MATTER. THE MICELLAR THEORY. 
 
 Physical Constitution of Living Matter. Micro- 
 scopic examination does not take us much farther. 
 The microscope, with the strongest magnification 
 of which it is capable at present, shows us nothing 
 beyond these links of aligned microsomes forming 
 the species of protoplasmic thread or mitome, whose 
 cellular body is a confused tangle or a very tangled 
 ball. It is not probable that direct sight can pene- 
 trate much farther than this. No doubt the micro- 
 scope, which has been so vastly improved, is capable 
 of still further improvement. But these improve- 
 ments are not indefinite. We have already reached 
 a linear magnification of 2000, and theory tells us 
 that a magnification of 4000 is the limit which cannot 
 be passed. The penetrating power of the instrument 
 is therefore near its culminating point. It has already 
 given almost all that we have a right to expect 
 from it. 
 
 We must, however, penetrate beyond this micro- 
 scopic structure at which the sense of sight has been 
 arrested. How is this to be done? When observa- 
 tion is arrested, hypothesis takes its place. Here 
 there are two kinds of hypotheses, the one purely 
 anatomical, the other physical. Anatomically, beyond 
 the visible microsomes there have been imagined 
 invisible hyper-microscopic corpuscles, the plastidules
 
 MORPHOLOGICAL UNITY OF LIVING BEINGS. 167 
 
 of Haeckel, the idioblasts of Hertwig, the pangenes of 
 de Vries, the plasomes of Wiesner, the gemmules of 
 Darwin, and the biophores of Weismann. 
 
 Biologists who have not got all that they hoped 
 from microscopic structure are therefore thrown back 
 on hyper-microscopic structure. 
 
 It is very remarkable that all this profound know- 
 ledge of structure has been so sterile from the point 
 of view of the knowledge of cellular functional activity. 
 All that is known of the life of the cell has been 
 revealed by experiment. Nothing has resulted from 
 microscopic observation but ideas as to configuration. 
 When it is a question of giving or imagining an 
 explanation of vital facts, of heredity, etc., biologists 
 unable to supply anything beyond the details of 
 structure revealed by anatomy have had recourse to 
 hypothetical elements, gemmules, pangenes, bio- 
 phores, and different kinds of determinants. 
 
 Anatomy never has explained and never will ex- 
 plain anything. "Happy physicists!" wrote Loeb, 
 " in never having known the method of research by 
 sections and stainings ! What would have happened 
 if by chance a steam engine had fallen into the hands 
 of a histological physicist? How many thousands of 
 sections differently stained and unstained, how many 
 drawings, how many figures, would have been pro- 
 duced before they knew for certain that the machine 
 is an engine, and that it is used for transforming 
 heat into motion 1" 
 
 The study of physical properties, continued on 
 rational hypotheses, has also thrown some light 
 on the possible constitution of living matter. The 
 gap between microscopical structure and molecular or 
 chemical structure has thus been filled. 
 
 12
 
 l68 LIFE AND DEATH. 
 
 The consideration of the properties of turgescence 
 and of swelling, which very generally belong to 
 organized tissues, and therefore to the organic 
 substance of protoplasm, has enabled us to obtain 
 some idea of its ultra-microscopic constitution. If 
 we wet a piece of sugar or a morsel of salt, before 
 they are dissolved they absorb and imbibe the water 
 without sensibly increasing their volume. It is quite 
 otherwise with a tissue (i.e., with a protoplasm) 
 when weakened in water as a preliminary. The 
 tissue, plunged into the liquid, absorbs it, swells, and 
 often grows considerably. And this water does not 
 lodge in the gaps, in pre-existing lacunar spaces, for 
 organic matter presents no gaps of this kind. It 
 does not resemble a porous mass with capillary 
 canals, such as sandstone, tempered mortar, clay, or 
 refined sugar. The molecules of water interpose 
 between and separate the organic molecules, thus 
 increasing by a sort of intussusception the intervals 
 separating the one from the other molecular intervals 
 escaping the senses, as do the molecules themselves 
 because they are of the same order of magnitude. 
 
 Micellar Theory. While pondering over this 
 phenomenon, an eminent physiologist, Nageli, was 
 led in 1877 to propose his niicellar theory. Micellae 
 are groups of molecules in the sense in which 
 physicists and chemists use the word. They are 
 molecular structures with a configuration. They 
 rapidly absorb water and are capable of fixing a 
 more or less thick and adherent layer of it to their 
 surface. In a word, they are aggregates of organic 
 matter and water. 
 
 There is therefore every reason for believing that 
 the microsomes of spongy protoplasm, the physical
 
 MORPHOLOGICAL UNITY OF LIVING BEINGS. 169 
 
 support or basis of cellular life, are groups of micella 
 formed of albuminoid substances and water. These 
 clustered forms, these micellae, are not absolutely 
 peculiar to organized matter. PfefFer, the learned 
 botanist, has pointed them out under another name, 
 tagmata, in the membranes of chemical precipitates. 
 
 Beyond this limit analysis finds nothing but the 
 chemical molecule and the atom. So that if we 
 wish to reconstruct the hierarchy of the materials of 
 constitution of the protoplasm in order of ascending 
 complexity, xve shall find at the foundation the atom or 
 atoms of simple bodies. They are principally carbon, 
 hydrogen, oxygen, nitrogen, the elements of all 
 organic compounds, to which may be added sulphur 
 and phosphorus. At the head we have the albu- 
 minoid molecule, or the albuminoid molecules, 
 aggregates of the preceding atoms. In the third 
 stage the micellae or tagmata, aggregates of albu- 
 minoids and water, are still too small to be observed 
 by the senses. They unite in their turn to form the 
 microsomes, the first elements visible to the micro- 
 scope. The microsomes, cemented by linin, form the 
 filaments or links which are called mitomes. The 
 living protoplasm is therefore nothing but a chain, or 
 tangled skein, or a spongy skeleton formed by its 
 filaments. 
 
 Such is the typical constitution of living matter 
 according to microscopic observation, supplemented by 
 a perfectly reasonable hypothesis, which is, so to speak, 
 only a translation of one of its most evident physical 
 properties. This relatively simple scheme has become 
 a complex scheme in the hands of later biologists. 
 On the micellar hypothesis, which seems almost 
 inevitable in its character, new hypotheses have been
 
 170 LIFE AND DEATH. 
 
 grafted, merely for the sake of convenience. Hence, 
 we are led farther and farther from the real truth, 
 and this is why, in order to explain the phenomena 
 of heredity, we find ourselves compelled to inter- 
 calate hypothetical elements between micella; and 
 the microsome in the higher hierarchy quoted above 
 gemmules, pangenes, plasomes, which are only mental 
 pictures or simple images to represent them. 
 
 4. THE INDIVIDUALITY OF COMPLEX BEINGS. 
 LAW OF THE CONSTITUTION OF ORGANISMS. 
 
 Individuality of Complex Beings. From the cellular 
 doctrine follows a remarkably suggestive conception 
 of living beings. The metazoa and the metaphytes 
 that is to say, the multicellular living beings which 
 may be seen with the eyes and do not require the 
 microscope to reveal them arc an assemblage of 
 anatomical elements and the posterity of a cell. 
 The animal or the plant, instead of being an 
 individual unity, is a " multitude," a term which is 
 used by Goethe himself when pondering, in 1807, over 
 the doctrine taught by Bichat ; or, according to the 
 equally correct expression of Hegel, it is a "nation " ; 
 it springs from a common cellular ancestor, just as 
 the Jewish people sprang from the loins of Abraham. 
 
 We now picture to ourselves the complex living 
 being, animal or plant, with its configuration which 
 distinguishes it from every other being, just as a 
 populous city is distinguished by a thousand 
 characteristics from its neighbour. The elements 
 of this city are independent and autonomous for the 
 same reason as the anatomical elements of the
 
 MORPHOLOGICAL UNITY OF LIVING BEINGS. IJI 
 
 organism. Both have in themselves the means of 
 life, which they neither borrow nor take from then- 
 neighbours nor from the whole. All these inhabitants 
 live in the same way. are nourished and breathe in 
 the same manner, all possessing the same general 
 faculties, those of man; but each has besides, his 
 profession, his trade, his aptitudes, his talents, by 
 which he contributes to social life, and by which in 
 his turn he depends on it Professional men, the 
 mason, the baker, the butcher, the manufacturer, the 
 artist, carry out different tasks and furnish different 
 products, the more varied, the more numerous and 
 the more differentiated, in proportion as the social 
 state has reached a higher degree of perfection. The 
 living being, animal or plant, is a city of this kind. 
 
 LaiL' of the Constitution of Organisms. Such is 
 the complex animal. It is organized like the city. 
 But the higher law of this city is that the conditions 
 of the elementary or individual life of all the ana- 
 tomical citizens are respected, the conditions being 
 the same for alL Food, air, and light must be 
 brought everywhere to each sedentary element ; the 
 waste must be carried off in discharges which will 
 free the whole from the inconvenience or the danger 
 of such debris ; and that is why we have the different 
 forms of apparatus in the circulatory, respiratory, 
 and excretory economy. The organization of the 
 whole is therefore dominated by the necessities of 
 cellular life. This is expressed in the law tf tlu con- 
 stitution of organisms formulated by Claude Bernard. 
 The organic edifice is made up of apparatus and 
 organs, which furnish to each anatomical element 
 the necessary conditions* and materials for the main- 
 tenance of life and the exercise of its activity. We
 
 172 LIFE AND DEATH. 
 
 now understand what is the life, and at the same 
 time what is the death, of a complex being. The 
 life of the complex animal, of the metazoon, is of two 
 degrees ; at the foundation, the activity proper to 
 each cell, elementary life, cellular life ; above, the 
 forms of activity resulting from the association of the 
 cells, the life of the whole, the sum or rather the 
 complex of elementary partial lives. There is a 
 solidarity between them produced by the nervous 
 system, by the community of the general circulatory, 
 respiratory apparatus, etc., and by the free com- 
 munication and mixture of the liquids which con- 
 stitute the media of culture for each cell. We shall 
 have an opportunity of recurring to current ideas as 
 to the morphological constitution of organisms.
 
 CHAPTER III. 
 
 THE CHEMICAL UNITY OF LIVING BEINGS. 
 
 The varieties and essential unity of the protoplasm Its 
 affinity for oxygen The chemical composition of proto- 
 plasmIts characteristic substances. I. The different 
 categories of albuminoid substances Nucleo-proteids 
 Albumins and histories Nucleins. 2. Constitution of 
 nucleins. ^ 3. Constitution of histones and albumins 
 Schultzenberger's analysis of albumin Kossol's analysis 
 The hexonic nucleus. 
 
 THE chemical unity of living beings corresponds to 
 their morphological unity. 
 
 T he Varieties and Essential Unity of the Proto- 
 plasm. One esfentfal feature of the living being is 
 that it is composed of matter peculiar to it, which is 
 called living matter, or protoplasm. But this is a 
 somewhat incorrect way of expressing the facts. 
 There is no unique living matter, no single proto- 
 plasm ; their number is infinite, there are as many as 
 there are distinct individuals. However like one 
 man may be to another, we are compelled to admit 
 that they differ according to the substance of which 
 they are constituted. That of the first offers a certain 
 characteristic personal to the first, and found in all 
 his anatomical elements ; similarly for the second. 
 With Le Dantec we shall say that the chemical 
 substance of Primus is not only of the substance of 
 man, but in all parts of his body and in all his con- 
 173
 
 174 LIFE AND DEATH. 
 
 stituent cells it is the exclusive substance of Primus; 
 and, in the same way, the living matter of another 
 individual Secundus will carry everywhere his per- 
 sonal impress, which differs from that of Primus. 
 
 But it is none the less true that this absolute 
 specificity is based with certainty only on differences 
 which from the chemical point of view are exceedingly 
 slight. All these protoplasms have a very analogous 
 composition. And, if we regard as negligible the 
 smallest individual, specific, generic, or ordinal varia- 
 tions we may then speak in a general manner of 
 protoplasm or living matter, 
 
 Experiment shows us, in fact, that the real living 
 substance apart from the products it manufactures 
 and can retain or reject is in every cell tolerably 
 similar to itself. The fundamental chemical re- 
 semblance of all protoplasms is certain, and thus 
 we may speak of their typical composition. We 
 may sum up the work of physiological chemistry for 
 the last three quarters of a century by affirming that 
 it has established the chemical unity of all living 
 beings that is to say, a very notable analogy in the 
 composition of their protoplasm. 
 
 This living matter is essentially a mixture of the 
 proteid or albuminoid substances, to which may be 
 added other categories of immediate principles, such 
 as carbohydrates and fatty matters. But the latter 
 are of secondary importance. The essential element 
 is the proteid substance. The most skilful chemists 
 have tried for more than half a century to discover 
 its composition. Only during the last few years 
 thanks to the researches of Kossel, the German 
 chemist, following on those of Schultzenberger and 
 Miescher we are beginning to know the outer walls
 
 THE CHEMICAL UNITY OF LHTXG BEINGS. 175 
 
 or the framework of the albuminoid molecule; in 
 other words, its chemical nucleus. 
 
 Physical C/tanuters of Protoplasm. About 1860 
 Ch. Robin thought that he had defined living matter 
 sufficiently or, at least, as perfectly as could be 
 expected at that time by attributing to it three 
 physical characteristics. They were : Absence of 
 homogeneity, molecular symmetry, and the association 
 of three orders of immediate principles albuminoids, 
 carbohydrates and fats. These characteristics assist, 
 but do not suffice, to define the organization. 
 
 No doubt the characteristics must be completed by 
 the addition of a certain number of more subtle 
 physical features. 
 
 One of them refers to the structure of protoplasm 
 as revealed by the microscope. Throughout the 
 whole of the living kingdom, from the bacteria studied 
 by Knnstler and Busquet to the most complicated 
 protozoa, protoplasmic matter presents the same 
 constitution, and in consequence, this structure of 
 the protoplasm must be considered as one of its 
 distinctive characters. It is not homogeneous; it 
 is not the last term of the visible organization : it is 
 itself organized. Experiment shows that it does not 
 resist breaking up or crushing. Mutilations cause 
 it to lose its properties. As for the kind of structure 
 that it presents, it may be expressed by saying that it 
 is that of a foamy emulsion. 
 
 We saw above that our knowledge as to the physical 
 condition of protoplasm has been completed by the 
 theories of Biitschli's micellae or Pfeffer's tagmata. 
 
 Properties of the Protoplasm. Its Affinity for 
 Oxygen. From the chemical point of view, living 
 matter presents a very remarkable property namely.
 
 176 LIFE AND DEATH. 
 
 a great affinity for oxygen. It absorbs it so greedily 
 that the gas cannot remain in a free state in its 
 neighbourhood. Living protoplasm, therefore, exer- 
 cises a reducing power. But it does not absorb 
 oxygen in this way for its own advantage ; oxygen 
 is not absorbed, as was supposed thirty years ago, to 
 supply fuel wherewith to burn the protoplasm. The 
 products are not those of its oxidation, of its own 
 disintegration. They are the products of combustion 
 of the reserve-stuff which is incorporated in it. 
 These substances have been supplied to it from 
 without, like the oxygen itself, with the blood. This 
 was proved by G. Pfltiger in 1872 to 1876. The 
 protoplasm is only the focus, the scene, or the 
 factor of combustion. It is not its victim, it does 
 not itself furnish the fuel. It works like the chemist, 
 who obtains a reaction with the substances that are 
 given to him. 
 
 As for the reducing power of protoplasm, A. 
 Gautier in 1881 and Ehrlich in 1890 have given fresh 
 proofs. A. Gautier in particular has insisted that the 
 phenomena of combustion take place, so to speak, 
 outside the cell, and at the expense of the products 
 which surround it ; while on the contrary the really 
 active and living parts of the nucleus and of the 
 cellular body, work protected by the oxygen, as in the 
 case of anaerobic microbes. 
 
 This result is of great importance. Burdon Sander- 
 son, the late learned professor of physiology at the 
 University of Oxford, has not hesitated to compare 
 it to the discovery of respiratory combustion by 
 Lavoisier. There is no doubt some exaggeration in 
 the comparison ; but there is, on the other hand, no 
 less exaggeration in supposing that it is not of great
 
 THE CHEMICAL U3OTY OF LIVING BEINGS. 177 
 
 importance. We may no longer in these days speak 
 without reservation of the vital vortex of Cuvier, and 
 of the incessant twofold movement of assimilation 
 and dissimilation which is ever destroying living 
 matter and building it up again. In reality, the 
 living protoplasm varies very little; it only under- 
 goes oscillations of very slight extent; it is the 
 materials, the reserve stuff on which it operates, which 
 are subject to continual transformations. 
 
 Chtmual Composition of Protoplasm. One of the 
 the three characters attributed by Ch. Robin to living 
 matter was its chemical composition, of which little 
 was known in his time. He insisted on the constant 
 presence in the living elements of three orders of 
 immediate principles proteid substances, carbo- 
 hydrates, and fatty bodies. In reality die proteid 
 substances, or albuminoids, alone are characteristic. 
 The two other groups, carbohydrates and fatty bodies, 
 are rather the signs and the products of the vital 
 activity, than constituents of the matter on which it is 
 exercised. 
 
 It is therefore on the knowledge of the proteid 
 substances that all the sagacity of biological chemists 
 has been exercised. Their efforts for thirty years, 
 and particularly in the last few years, have not been 
 barren ; they enable us to give a first rough sketch of 
 the constitution of these substances. 
 
 i. THE CHARACTERISTIC SUBSTANCES OF THE 
 PROTOPLASM. THE NUCLEO-PROTEIDS. 
 
 The Different Categories of Albuminoid Substances. 
 Albuminoid or proteid substances are extremely 
 complex compounds, much more so than any of those
 
 178 LIFE AND DEATH. 
 
 which are being constantly studied by the chemist. 
 They also are to be found in great variety. It has 
 been difficult to separate them one from the other, to 
 characterize them rigorously, or, in other words, to 
 classify them. However, it has been done now, and 
 we distinguish three classes which are differentiated 
 at once from the physiological and from the chemical 
 points of view. The first comprises the complete or 
 typical albuminoids. They are the proteids or nnclco- 
 albuminoids. They are to be found in the most active 
 and most living parts of the protoplasm, and therefore 
 in the spongioplasm of the cell and around the 
 nucleus. The second group is formed of albumins 
 and globulins, compounds already simpler, fragments 
 derived from the destruction of the preceding, into 
 which they enter as constituent elements. In the 
 isolated state they do not belong to the really living 
 protoplasm; they exist in the cellular juice, in the 
 interstitial and circulating liquids in the blood and in 
 the lymph. The third category comprises real but 
 incomplete albuminoids. They are to be found in 
 the portions of the economy which have a specialized 
 or attenuated life, and are destined to serve as a 
 support to the more active elements i.e., they con- 
 tribute to the building up of the bony, cartilaginous, 
 conjunctive, elastic tissues. They are called allnt- 
 moids. It is naturally the first group, that of the 
 proteids i.e., of the complete and characteristic com- 
 pounds of the living substance upon which the 
 attention of the physiologists must be fixed. It is 
 only quite recently that the clear definition of these 
 substances has been given, and proteid compounds 
 detected in the confused mass. 
 
 TJie Nudeo-proteids. This progress in the char-
 
 THE CHEMICAL UNITY OF LIVING BEINGS. I/Q 
 
 acterization and specification of the proteids required 
 in the first place a knowledge of two particular com- 
 pounds, the nucleins and the liistoms. This did not 
 become possible until after the researches of Miescher 
 and Kossel on the nucleins, which went on from 1874 
 to 1892, and those of Lilienfeld and d'Yvor Bang on 
 the histpnes, from 1893 to l8 99- The complete 
 albuminoids are constituted by the combination of 
 two kinds of substances albumins or histones on the 
 one hand, and nucleins on the other. By combining 
 solutions of albumins or histones with solutions of 
 nuclein, the synthesis of the proteid is effected. The 
 study of the properties and characteristics of these 
 nucleo-albumins and nucleo-histones is going on at 
 the present moment It is being carried out with 
 much method and with wonderful patience by the 
 German school. 
 
 All the proteids contain phosphorus in addition to 
 the five chemical elements, carbon, oxygen, hydrogen, 
 nitrogen, and sulphur, which are common to the 
 other albuminoids. Another interesting feature in 
 their history is that the action of the gastric juice 
 divides them into their two constituents : the nuclein, 
 which is deposited and resists the destructive action 
 of the digestive liquid, and the albumin or histonc, 
 which on the contrary experiences this action with 
 the usual consequences. Thus the gastric juice 
 furnishes a process which is very simple and very 
 convenient in the analysis of the proteids. 
 
 Localisation of tlu Nudeo- Proteids. What we said 
 before as to the important physiological role of the 
 cellular nucleus may arouse the expectation that in it 
 will be found the living matter which is chemically 
 the most differentiated, the albuminoids of highest
 
 l8o LIFE AND DEATH. 
 
 rank i.e., the nucleo-proteids and their constituents. 
 Not that they would not be found in the protoplasm 
 of the rest of the cell, but there is certainly a risk 
 that they would be less concentrated there and more 
 blended with accessory products ; they are there con- 
 nected with much more secondary vital functions. 
 This conclusion inspired the early researches of Pro- 
 fessor Miescher, of Basle, in 1874, and, twenty years 
 later, those of Professor Kossel, one of the most 
 eminent physiological chemists in Germany. 
 
 In fact, these compounds have been found in all 
 tissues which are rich in cellular elements with well- 
 developed nuclei. The white globules of the blood 
 furnished to Lilienfeld the first nucleo-histone ever 
 isolated. The red globules themselves, when they 
 possess a nucleus, which is the case in birds and 
 reptiles as well as in the embryo of mammals, contain 
 a nucleo-proteid which was easily isolated by Plosz and 
 Kossel. Hammarsten, the Swedish chemist, who has 
 acquired a great reputation from his researches in 
 other domains of biological chemistry, prepared the 
 nucleo-proteids of the pancreas in 1893. They have 
 been obtained from the liver, from the thyroid 
 gland (Ostwald), from brewers' yeast (Kossel), from 
 mushrooms, and from barley (Petit). They have 
 been detected in starchy bodies and in bacteria 
 (Galeotti). 
 
 2. CONSTITUTION OF NUCLEINS. 
 
 Constitution of Nucleins. Our path is already 
 marked out if we wish to penetrate farther into the 
 constitution of these proteids; which are the imme-
 
 THE CHEMICAL UNITY OF LIVING BEINGS. l8l 
 
 diate principles highest in complexity among those 
 which form the living protoplasm. We must analyze 
 the two components, the albumins and the histones on 
 the one hand, and the nucleins on the other. As for 
 the nucleins, this has already been done, or very 
 nearly so. 
 
 Kossel, in fact, decomposed the nuclein by a series 
 of very carefully arranged operations, and has reduced 
 it step by step to its crystallizable organic radicals. 
 At each stage that we descend in the scale of 
 simplification a body appears which is more acid and 
 more rich in phosphorus. At the third stage we 
 come to phosphoric acid itsel The first operation 
 divides the nuclein into two substances: the new 
 albumin and nucleinic acid. After separating these 
 elements they can be reunited : a solution of albumin 
 with a solution of nucleinic acid reconstitutes the 
 nuclein. A second operation separates the nucleinic 
 acid in its turn into three parts. One is a body of 
 the nature of the sugars /.*., a carbohydrate. The 
 appearance of a sugar in this portion of the molecule 
 of nucleinic acid is an interesting fact and fertile in 
 results. The second part is constituted by a mixture 
 of nitrogenous bodies, well known in organic chemistry 
 under the name of xantJiic bases (xanthin, hypo- 
 xanthin, guanin, and adenin). The third part is a 
 very acid body and full of phosphorus thymic acid. 
 If in a third and last operation the thymic acid is 
 analyzed, it is finally separated into phosphoric acid 
 and into thymene, a crystallizable base, and thus we 
 are brought back to the physical world, for all these 
 bodies incontestably belong to it
 
 182 LIFE AND DEATH. 
 
 3. THE CONSTITUTION OF HISTONES AND 
 ALBUMINS. 
 
 Constitution of Histones. But we are only half-way 
 through our task. We are acquainted in its origin 
 with one of the genealogical branches of the proteid, 
 the nucleinic branch. We must also learn something 
 of the other branch, the albumin or histone branch. 
 But on this side the problem assumes a character of 
 difficulty and complexity which is admirably adapted 
 to discourage the most untiring patience. 
 
 The analysis of albumin for a long time baulked 
 the chemist. " Here," said Danilewsky, "we come to 
 a closed door which resists all our efforts." We know 
 how vastly interesting what is taking place on the 
 other side must be, but we cannot get there. We get 
 a mere glimpse through the cracks or chinks which 
 we have been able to make. 
 
 This analysis of albuminous matter at first requires 
 great precautions. The chemist finds himself in the 
 presence of architecture of a very subtle kind. The 
 molecule of albumin is a complex edifice which has 
 used up several thousand atoms. To perceive the 
 plan and structure, it must be dismantled and 
 separated into parts which are neither too large nor 
 too small. Such careful demolition is difficult. 
 Processes too rough or too violent will reduce the 
 whole to the tiniest of fragments. It is a statue 
 which may be reduced to dust, instead of being 
 separated into recognizable fragments, easily fitted in 
 place along their fractured faces. 
 
 Analysis of Albumin by Schiitzenberger. Schutzen- 
 berger, a chemist of great merit, attempted (about
 
 THE CHEMICAL UNITY OF LIVING BEINGS. 183 
 
 1875) this thankless task. Others before him had 
 experimented in various ways. Two Austrian 
 scientists, Hlasitwetz and Habermann, in 1873, an< ^ 
 a little later Drechsel in 1892, had used concen- 
 trated hydrochloric acid to break down albumin. 
 They also employed bromine for the same purpose. 
 More recently Fuerth had used nitric acid with a 
 similar object. Schiitzenberger tried another way. 
 The battering ram which he used against the edifice 
 of albumin was a concentrated alkali, baryta. He 
 warmed the white of an egg with barium hydrate 
 in a closed vessel at a temperature of 2CO 3 . The 
 albumin of egg then divides into a certain number of 
 simpler groups. The difficulty is to isolate and to 
 recognize each part in this mass of the materials of 
 demolition. That can be done by the aid of the 
 processes of direct analysis. By mentally combining 
 these different fragments, the original building is 
 reconstructed. This method of demolition is certainly 
 too rough and violent Schiitzenberger's operation 
 gives us very fine fragments small molecules of free 
 hydrogen, of ammonia, of carbonic, acetic, and oxalic, 
 acids which reveal extreme pulverization. These 
 products represent about a quarter of the total mass. 
 The other three-quarters are formed of larger frag- 
 ments, the examination of which is most instructive. 
 They belong to four groups. The first comprises five 
 or six bodies, amido-acids or leucins. It proves the 
 existence in the molecule of albumin of compounds of 
 the series of fats />., arranged in an open chain. 
 The second group is formed by tyrosin and kindred 
 products i.e., by the bodies of the aromatic series, 
 which force us to acknowledge the presence in the 
 molecule of albumin of a benzene nucleus. The third 
 
 13
 
 184 LIFE AND DEATH. 
 
 group forms around the nucleus known to chemists 
 under the name of pyrrol. The fourth comprises 
 bodies such as the glucoproteins, connected with the 
 sugars, or carbohydrates. 
 
 Does the fact that the molecule of albumin is 
 destroyed in producing these compounds raise the 
 question as to whether it implies the idea that in 
 reality they pre-exist in it? Chemists are rather 
 inclined to admit this. However, the conclusion does 
 not appear to be permissible. Duclaux considers it 
 doubtful. It is not certain that all these fragmentary 
 bodies pre-exist in reality, and it is no more certain 
 that a simple bringing of them together represents 
 the primitive edifice. Materials of demolition from a 
 house that has been pulled down give no idea of its 
 natural architectural character. There is only one 
 way of justifying the hypothesis, and that is to re- 
 constitute the original molecule of albumin by bring- 
 ing the fragments together. We have not got to that 
 stage yet. The era of syntheses of such complexity 
 is more or less near, but it has certainly not yet 
 begun. 
 
 Moreover, it is not correct to say that the simple 
 juxtaposition of the surfaces of fracture will reproduce 
 the initial body. The fragments, so far as analysis 
 has obtained them, are not absolutely what they might 
 have been in the original structure. There they 
 adhered the one to the other, not only by the mere 
 contact of their surfaces of fracture, as is supposed, 
 but in a slightly more complex manner. The frag- 
 ments of the molecule are joined by bonds. V/e can 
 picture them to ourselves by supposing these bonds 
 to be like hooks. The hooks, which could only be 
 broken by violence, are called by the chemists
 
 THE CHEMICAL UNITY OF LIVING BEINGS. 185 
 
 satisfied atomicities. These atomicities, set free by 
 the breaking up, cannot remain in this condition ; 
 they must be satisfied anew. The hook tries to attach 
 itself. In Schiitzenberger's experiment the addition 
 of \vater provides for this necessity. A molecule of 
 water (H ? O) splits into two, the hydrogen (H) on the 
 one side and the hydroxyl (OH) on the other. These 
 two elements cling to the liberated bonds of the 
 fragments of the molecule of albumin, and thus 
 the bodies were found complete. Schiitzenberger's 
 experiment, was too violent, too radical, and it gave 
 too large a number of fragments, with their free hooks 
 and atomicities unsatisfied, for rather a large pro- 
 portion of the water added disappeared during the 
 experiment In one case this quantity was as much 
 as 17 grammes per 100 grammes of albumin. The 
 molecules of this water were employed in the 
 reparation of the incomplete fragmentary molecules 
 of the albumin. 
 
 It follows that Schiitzenberger's experiment gave 
 too large a number of very small pieces corresponding 
 to far too great a pulverization. The very small frag- 
 ments are the molecules of acids such as acetic acid, 
 oxalic acid, carbonic acid, molecules of ammonia, 
 and even of hydrogen, which we know we are setting 
 free. 
 
 But, apart from these products which represent a 
 quarter of the molecule of albumin submitted to 
 analysis, the other three quarters represent larger 
 fragments which may be considered as the real 
 constituents of the building. Thus we find four 
 kinds of groups which may be accepted as natural 
 The first of these groups is that of the leucins or 
 amido-acids. It proves the existence in the molecule
 
 l86 LIFE AND DEATH. 
 
 of albumin of compounds of the fatty series. There 
 is also an aromatic group a pyridine group and a 
 group belonging to the category of sugars. Imagine 
 a certain grouping of these four series. This would 
 be the nucleus of the molecule of albumin. If we 
 graft on to this nucleus, on to this framework as it 
 were, so many annexes, or lateral chains, the building 
 will be loaded with embellishments ; it will have 
 been made unstable and ipso facto appropriate for the 
 part that it plays in the incessant transformations 
 of the organism. 
 
 Kossefs Analysis. Hexonic Nucleus. Kossel has 
 approached the problem in another fashion. He 
 did not attempt to attack the albumin of the egg. 
 This body is, in fact, a heterogeneous mixture as 
 complex as the needs of the embryo of which it forms 
 the food. Kossel tried a physiologically simpler 
 albuminoid. He got it from an anatomical element 
 having no nutritive role, of a very elementary 
 organization and physiological functional activity, 
 and yet one of energetic vitality the male generating 
 cell. Instead of the hen's egg he therefore analyzed 
 the milt of fish, and, in the first place, of salmon. As 
 was to be expected from what has been said of the 
 proteids, this living matter gives a combination of 
 the nuclein, already known, with an albumin. The 
 latter is abundant, forming a quarter of the total 
 mass. Its reaction is strongly alkaline, which is the 
 general characteristic of the variety of albumin known 
 by the name of histones. Miescher, the learned 
 chemist of Basle, who had noticed this basic albumin 
 when working on the Rhine salmon, gave it the name 
 of protamin. This is the substance submitted by 
 Kossel to analysis in preference to the albumin of
 
 THE CHEMICAL UNITY OF LIVING BEINGS. 187 
 
 egg, so dear to the chemists who had preceded him. 
 The disintegration of this molecule, instead of giving 
 the series of bodies obtained by Schutzenberger, 
 gave but one, a real chemical base, arginin. At the 
 first trial the albumin examined was reduced to a 
 simple crystallizable element The conclusion was 
 obvious. The protamin of salmon is the simplest of 
 albumins. To form this elementary proteid substance 
 a hexonic base with water is all that is required. 
 
 Continuing on these lines other male generating 
 cells were examined and a series of protamines con- 
 structed on the same type was found, and these 
 albuminous bodies proved to be formed of a base or 
 mixture of analogous hexonic bases : arginin, histi- 
 din, and lysin all bodies closely akin in their pro- 
 perties and entirely belonging to the physical world. 
 
 Once aware of the existence of this fundamental 
 nucleus, chemists found it in the more complex 
 albumins where it had been missed. It was found in 
 the albumin of egg hidden under the mass of other 
 groups. It was recognized in all animal or vegetable 
 albumins. The nuclei of Schutzenberger may be 
 missing. Hexonic bases are the constant and 
 universal element of all varieties of albumins. They 
 prevail in the chemical nucleus of the albuminous 
 molecule, and perhaps as is suggested by Kossel, 
 they may form it exclusively. All the other elements 
 are superadded and accessory. The essential type of 
 this molecular edifice, sought for so long, is known at 
 last 
 
 Conclusion. To sum up, the chemical unity of 
 living beings is expressed by saying that living 
 matter, protoplasm, is a mixture or a complex of 
 proteid substances with an hexonic nucleus.
 
 CHAPTER IV. 
 
 THE TWOFOLD CONDITIONING OF VITAL 
 PHENOMENA. IRRITABILITY. 
 
 Appearance of internal activity of the living being Vital 
 phenomena regarded as a reaction of the ambient world. 
 I. Extrinsic conditions The optimum law. 2. Intrinsic 
 conditions The structure of organs and apparatus How 
 experiment attacks the phenomena of life. Generalization 
 of the law of inertia Irritability. 
 
 Instability. Mutability. The Appearance of Internal 
 Activity of the Living Being. One of the most 
 remarkable characteristics of the living being is its 
 instability. It is in a state ofjpntinual change. The 
 simplest of the elementary beings, the plastid, grows 
 and goes on growing and becoming more complex, 
 until it reaches a stage at which it divides, and thus 
 rejuvenated it commences the upward march which 
 leads it once again to the same segmentation. Its 
 evolution is thus betrayed by its growth, by the 
 variations of form which correspond to it, and by 
 its divisjpn. 
 
 If it be a question of beings higher in organiza- 
 tion than the cellular element the evolutionary- 
 character of this mutability becomes more obvious. 
 The being is formed, it grows ; then in most cases, 
 after having passed through the stages of youth and 
 adult age, it grows old, declines and dies, and is 
 188
 
 VITAL PHENOMENA. 189 
 
 disorganized after having gone through what we may 
 call an ideal trajectory. This march in a fixed 
 direction with its points of departure, its degrees, and 
 its termination, is a repetition of the path that the 
 ancestors of the living being have already followed. 
 
 Here, then, is a characteristic fact of vitality, or 
 rather there are two facts. The one consists in this 
 morphological and organic evolution, the negation of 
 immutability, the negation 6F tne indefinite main- 
 tenance of a permanent state or form which is 
 regarded, on the contrary, as the condition of inert, 
 fixed stable bodies, eternally at rest. The other 
 consists in the repetition, realized by this evolution, 
 of the similar evolution of its ancestors ; this is a 
 fact of heredity. Finally, evolution is always in a 
 cycle that is to say. that it comes to an end which 
 brings the course of things to their point of departure. 
 
 This kind of internal activity of the living being 
 is so striking, that not only does it serve us to 
 differentiate the living being from the inert body, 
 but it gives rise to the illusion of a kind of internal 
 demon, vital force, manifested by the more or less 
 apparent acts of the life of relation, of the motricity, 
 of the displacement, or by the less obvious acts of 
 vegetative life. 
 
 Vital PJienomena regarded as a Reaction of the 
 Ambient World. Their Twofold Conditioning. In 
 reality, as the doctrine of energetics teaches us, the 
 phenomena of vitality are not the effect of a purely 
 internal activity. They are a reaction of the environ- 
 ment. "The idea of life," says Auguste Comte, 
 " constantly assumes the necessary correlation of two 
 indispensable elements : an appropriate organism 
 and a suitable environment. It is from the reciprocal
 
 190 LIFE AND DEATH. 
 
 action of these two elements that all vital phenomena 
 inevitably result." The environment furnishes the 
 living being with three things: its matter, its 
 energy, and the exciting forces of its vitality. All 
 vital manifestation results from the conflict of two 
 factors : the extrinsic factor which provokes its 
 appearance ; the intrinsic factor, the very organiza- 
 tion of the living body, which determines its form. 
 Bichat and Cuvier saw in the phenomena of life the 
 exclusive intervention of a principle of action entirely 
 internal, checked rather than aided by the universal 
 forces of nature. The exact opposite is true. The 
 protozoan finds the stimuli of its vitality in the 
 aquatic medium which is its habitat. The really 
 living particles of the metazoan that is to say, its 
 cells, its anatomical elements meet these stimuli in 
 the lymph, in the interstitial liquids which bathe 
 them and which form their real external environ- 
 ment. 
 
 Auguste Comte thoroughly understood this truth, 
 and has clearly expressed it in the passage we have 
 just quoted. Claude Bernard has fully developed it 
 and given it its classical form. 
 
 In order to manifest the phenomena of vitality, 
 the elementary being, the protoplasmic being, re- 
 quires from the external world certain favourable 
 conditions ; these it finds there, and they may be 
 called the stimuli, or extrinsic conditions of vitality. 
 This being possesses no initiative or spontaneity in 
 itself, it has only a faculty of entering into action 
 when an external stimulus provokes it. This sub- 
 jtection of the living matter is called irritability. 
 The term expresses that life is not solely an internal 
 attribute, but an internal pjrinc|ple of action.
 
 VITAL PHENOMENA. IQI 
 
 i. EXTRINSIC CONDITIONS. 
 
 Extrinsic Conditions. By showing that every vital 
 manifestation results from the conflict of two factors : 
 the extrinsic or physico-chemical conditions which 
 determine its appearance, and the intrinsic or organic 
 conditions which regulate its form, Claude Bernard 
 dealt a mortal blow at the old vitalist theories. For 
 he has not only asserted the close dependence of the 
 two kinds of factors, but he has shown them in action 
 in most physiological phenomena. The study of the 
 extrinsic or physico-chemical conditions necessary to 
 vital manifestations teaches us our first truth 
 namely, that they are not infinitely varied as might 
 be supposed. They present, on the contrary, a 
 remarkable uniformity in their essential qualities. 
 The fundamental conditions are the same for the 
 animal or vegetable cells of every species. They are 
 four in number : moisture^ the air, or rather oxygen, 
 foot, and a certain chemical constitution of the medium, 
 and the last condition, the enunciation of which 
 seems vague, becomes more precise if we look at it 
 a little closer. The chemical constitution of media 
 favourable to life, the media of culture, obeys three 
 general laws. It is the knowledge of these laws 
 which formerly enabled Pasteur, Raulin, Cohn, and 
 Balbiani to provide the media appropriate to the 
 existence of certain relatively simple organisms, and 
 thus to create an infinitely valuable method for 
 the study of nutrition, etc , namely, the method of 
 artificial cultures^ numerous developments of which 
 have been shown us by microbiology and physiology". 
 
 The Optimum Laze. It has been saio", and it is 
 more than a play on words, that the conditions of
 
 IQ2 LIFE AND DEATH, 
 
 the vital medium were the conditions of the juste 
 milieu. Water is wanted, there must not be too 
 much or too little. Oxygen is necessary, and also in 
 certain proportions. Heat is required, and for that, 
 too, there is an optimum degree. Certain chemical 
 compounds are needed and, in this respect too, there 
 must also be optima proportions. 
 
 Water is a constituent element of the organisms. 
 They contain fixed proportions for the same tissue, 
 proportions varying from one tissue to another 
 (between and T 9 <y). The cell of a living tissue re- 
 quires around it an aqueous atmosphere, formed by 
 the different juices of the organism, the interstitial 
 liquids, the blood, and the lymph. We are deceived 
 by appearances when we distinguish 'between aerial, 
 aquatic, and land-dwelling animals, and when we 
 speak of the air, the water, and the land as their 
 natural environment. If we go to the bottom of 
 things, and fix our attention on the real living 
 unities, on the cells of which the organism is composed, 
 we shall find around them the juices, rich in water, 
 which are their real environment. If these juices are 
 diluted or concentrated the least in the world, life 
 stops. The cell, the whole animal, falls into a state 
 of latent life, or dies. " All living beings are aquatic," 
 said Claude Bernard. " Beings that live in the air are 
 in reality wandering aquariums," said another physio- 
 logist. " No moisture, no life," wrote Preyer. The 
 environment must contain water, but it must contain 
 it in certain proportions. In the higher animals 
 there is a mechanism which works automatically to 
 keep at a constant level the quantity of water in the 
 blood. Researches on the lavage of the blood (A. 
 Dastre and Loye) have clearly shown this.
 
 VITAL PHENOMENA. 193 
 
 Oxygen is also necessary to life. It is \hepabulum 
 vitcs. But the discovery of the beings called by 
 Pasteur anacrobia appears to contradict this state- 
 ment Pfeffer, the illustrious botanist, was certain, 
 in 1897, that the dogma of the necessity of oxygen 
 no longer held good. This is no longer tenable. 
 In 1898 Beijerinck carried out most careful re- 
 searches on anaerobia said to have been cultivated 
 in a vacuum, such as the bacteria of tetanus and the 
 septic vibrion ; or on those to which oxygen seems to 
 be a poison, such as the butyric and the butylic 
 ferments, the anaerobia of putrefaction, the reducing 
 spirilla of the sulphates. All use free oxygen. They 
 consume very little it is true ; they are micro-aerobia. 
 The other organisms, on the contrary, need more. 
 They are macro-aerobia or simply aerobia. Besides, 
 if the so-called anaerobia take little or no free 
 oxygen, it matters little. They take the oxygen 
 in combination. It may be said with L. Errera 
 that they have an affinity for oxygen, for they 
 extract it from its combinations, and that " they 
 are so well adapted to this mode of existence that 
 life in the open air being too easy no longer suits 
 them." There are for the different animal species 
 different optima of oxygen. 
 
 Living beings require a certain amount of heat. 
 Life, which could not have existed on the globe when 
 it was incandescent, will not be able to exist when it 
 is frozen. For each organism and each function 
 there is a maximum and a minimum of temperature 
 compatible with activity. There is also an optimum. 
 For instance, the optimum is 29* C for the germination 
 of corn. 
 
 The condition of the optimum exists in the same
 
 194 LIFE AND DEATH. 
 
 way for the chemical composition of the vital medium 
 and for the other ambient physical conditions, such 
 as atmospheric pressure. 
 
 It is therefore a law of universal scope, a regulating 
 law, as it were, of life. Life is a function of extrinsic 
 variables, water, air, heat, the chemical composition of 
 the medium, and pressure. " Every vital phenomenon 
 begins to be produced, starting from a certain stage 
 of the variable (minimum), becomes more and more 
 vigorous as it increases up to a determinate value 
 (optimum), weakens if the variable continues to in- 
 crease, and disappears when it has reached a certain 
 limiting value (maximum)." This law, proved by 
 Sachs, the German botanist, in 1860, apropos of the 
 action of temperature on the germination of plants, 
 by Paul Bert in 1875, apropos of the action of oxygen 
 and of atmospheric pressure on animals, and already 
 formulated at that time by Claude Bernard, was 
 illustrated by Leo Errera in 1895. It is a law of 
 moderation. It expresses La Fontaine's " rien de 
 trap" Terence's " ne quid nimis" the (MjSev ayav of 
 Theognis, and the biblical phrase " omnia in mensura 
 et numero et pondere" L. Errera sees the profound 
 cause of this optimum law in the properties of the 
 living protoplasm, which are mean properties. It 
 is semi-liquid. It is composed of albuminoid sub- 
 stances, which can stand no extremes either from the 
 physical or from the chemical points of view. 
 
 2. INTRINSIC CONDITIONS. THE LAW OF THE 
 CONSTITUTION OF ORGANS AND APPARATUS. 
 
 Laiv of the Constitution of Organs and Apparatus. 
 If we consider more highly organized beings, the
 
 VITAL PHENOMENA. IQ5 
 
 influence of the intrinsic conditions appears quite 
 as clearly. As we have seen, this is so that the 
 requisite fundamental materials may be spent by 
 each element in suitable proportions, water, chemical 
 compounds, air, and heat, that organs may be added 
 to organs, and that apparatus may be set to work in 
 complex structures. Why a digestive apparatus? 
 To prepare and introduce into the internal medium 
 liquid materials which are necessary to life. Why a 
 respiratory apparatus? To impart the vital gas 
 necessary to the cells, and to expel the gaseous 
 excrement, the carbonic acid which they reject. 
 Why a circulatory apparatus? To transport and 
 renew this medium throughout. The apparatus, the 
 functional wheels, the vessels, the digestive and 
 respiratory mechanisms do not exist for themselves, 
 like the random sketches of an artistic nature. They 
 exist for the innumerable anatomical elements which 
 people the economy. They are arranged to assist 
 and more rigorously to regulate cellular life with 
 respect to the extrinsic conditions which it demands. 
 They are, in the living body, as in civilized society, 
 the manufactories and the workshops which provide 
 for the different members of society dress, warmth, 
 and food. In a word, the law of tJie construction of 
 organisms or of the bringing to perfection of an 
 organism is the same as the law of cellular life. It 
 is otherwise suggestive as the law of division of 
 physiological labour formerly enunciated by Henry 
 Milne-Edwards; and in every case it has a more 
 concrete significance. Finally, it brings the organic 
 functional activity into relation with the conditions of 
 the ambient medium. 
 
 How Experiment acts on the Phenomena of Life.
 
 ig6 LIFE AND DEATH. 
 
 The two orders of conditions, the one provided by the 
 being itself, the other by external agents, are equally 
 indispensable and therefore of equal importance or 
 dignity. But they are not equally accessible to the 
 experimentalist. It is not easy to exercise on the 
 organization direct and measurable actions. On the 
 contrary, the physical conditions are in the hands 
 and at the discretion of the experimenter. By them 
 he may reach the vital manifestations as they appear, 
 stimulate or check them, defer or precipitate them. 
 Thus, for instance, the physiologist suspends or re- 
 establishes at his will full vital activity in a multitude 
 of reviviscent or hibernating beings, such as grains, 
 the infusoria capable of encystment, the vibrio, the 
 tardigrade, the cold-blooded animals, and perennial 
 plants. 
 
 The ambient world therefore furnishes to the animal 
 and to the vegetable, whole or fragmentary, those 
 materials of its organization which are at the same 
 time the stimuli of its vitality. That is to say, the 
 vital mechanism would be a dormant and inert 
 mechanism if nothing in the surrounding medium 
 could provoke it to action or give it a check. It 
 would be a kind of steam engine without coal and fire. 
 
 Living matter, in other words, does not possess real 
 spontaneity. As I have shown elsewhere, the law of 
 inertia which it is supposed it obeys with inert bodies 
 is not special to them. It is applied to the living 
 bodies whose apparent spontaneity is only an illusion 
 contradicted by physiology as a whole. All the vital 
 manifestations are responses to a stimulus of acts 
 provoked, and not of spontaneous acts. 
 
 Generalization of the Laiv of Inertia in Living 
 Bodies. Irritability. In fact, vulgar prejudice opposes
 
 VITAL PHENOMEMA. 197 
 
 this view. The opinion of the average man distrusts 
 it It applies the law of inertia only to inert matter. 
 This is because the vital response does not always 
 immediately succeed the external stimulus, and is not 
 always proportional to it But it is sufficient to have 
 seen the flywheel of a steam engine to understand 
 that the restitution of a mechanical force cannot be 
 instantaneous. It is sufficient to have had a finger 
 on the trigger of a firearm to know that there is no 
 necessary proportion between the intensity of the 
 stimulus and the magnitude of the force produced. 
 Things happen in the living just as in the inert 
 machine. 
 
 The faculty of entering into action when provoked 
 by an external stimulus has received, as we have said, 
 the name of irritability. The word is not used of 
 inert matter. However, the condition of the latter is 
 the same. But there is no need to affirm its irrita- 
 bility, because no one denies it. We know perfectly 
 well that brute matter is inert, that all the manifesta- 
 tions of activity of which it is the theatre are provoked. 
 Inertia is for it the equivalent of irritability in living 
 matter. But while it is not necessary to introduce 
 this idea into the physical sciences, where it has 
 reigned since the days of Galileo, it was, on the 
 contrary, necessary to affirm it in biology, precisely 
 because it was in biology that the opposing doctrine 
 of vital spontaneity ruled supreme. 
 
 Such was the view held by Claude Bernard. He 
 never varied on this point. Irritability^ said he, is the 
 property possessed " by every anatomical element 
 (that is to say, the protoplasm which enters into its 
 constitution) of being stimulated into activity and of 
 reacting in a certain manner under the influence of
 
 ig8 LIFE AND DEATH. 
 
 the external stimuli." He could not claim that this 
 was a distinguishing characteristic between living 
 bodies and brute bodies, and that all the less because 
 he always tried to efface on this point the distinctions 
 which were current in his time, and which were 
 established by Bichat and Cuvier. And so also Le 
 Dantec does not seem to have thoroughly grasped 
 the ideas of the celebrated physiologist on this point 
 when he asserts, as if he were thereby contradicting 
 the opinion of Claude Bernard and his school, that 
 irritability is not something peculiar to living bodies. 1 
 
 1 These ideas are clearly brought to light in a series of 
 articles in the Revue Philosophique, published in 1879 under 
 the title of " La probleme physiologiqtie de la vie," and endorsed 
 by A. Dastre in his commentary on the Plienouienes comimtns 
 aux animaux et aux plantes.
 
 CHAPTER V. 
 
 THE SPECIFIC FORM. ITS ACQUISITION. 
 ITS REPARATION. 
 
 i. Specific form not special lo living beings Connected with 
 the whole of the material conditions of the body and the 
 medium Is it a property of chemical substance? $ 2. 
 Acquisition and re-establishment of the specific form- 
 Normal regeneration Accidental regeneration in the pro- 
 tozoa and the plastids In the metazoa. 
 
 i. THE SPECIFIC FORM. 
 
 The Specific Form is not Peculiar to Living Beings. 
 The position of a specific form the acquisition of 
 this typical form progressively realized the re-estab- 
 lishment when some accident has altered it these 
 are the features which we consider distinctive of living 
 beings, from the protophytes and the lowest protozoa 
 to the highest animals. Nothing gives a better idea 
 of the unity and the individuality of the living being 
 than the existence of this typical form. We do not 
 mean, however, that this characteristic belongs to the 
 living being alone, and is by itself capable of defining 
 it We repeat that this is not a case with any 
 characteristic In particular the typical form belongs 
 to crystal as well as to living beings. 
 
 T/ie Specific Form depends on the sum of Material 
 Conditions of the Body and the Medium. The con^- 
 sideration of mineral bodies shows us form dependent 
 199 14
 
 200 LIFE AND DEATH. 
 
 on the physico-chemical conditions of the body and 
 the medium. The form depends mainly on physical 
 conditions in the cases of a drop of water falling from 
 a tap, of the liquid meniscus in a narrow tube, of a 
 small navel-shaped mass of mercury on a marble 
 slab, of a drop of oil "emulsioned" in a solution, and 
 of the metal which is hardened by hammering or 
 annealed. In the case of crystals the form depends 
 more on chemical conditions. It is crystallization 
 which has introduced into physics the idea that has 
 now become a kind of postulate namely, that the 
 specific form is connected with the chemical composi- 
 tion. However, it is sufficient to instance the dimor- 
 phism of a simple body, such as sulphur, sometimes 
 prismatic, sometimes octahedric, to realize that sub- 
 stance is only one of the factors of form, and that the 
 physical conditions of the body and of the medium 
 are other factors quite as influential. 
 
 Is the Specific Form a Property of tlie CJiemical 
 Substance ? How much truer this restriction would 
 be if we consider, instead of a given chemical com- 
 pound, an astonishingly complex mixture, such as 
 protoplasm or living matter, or the more complex 
 organism still the cell, the plastid. 
 
 Are there not great differences between the sub- 
 stance of the cellular protoplasm, or cytoplasmic 
 substance, and that of the nucleus? Should we not 
 distinguish in the former the hyaloplasmic substance; 
 the microsomic in the microsomes; the linin between 
 its granulations ; the centrosomic in the centrosome; 
 the archoplasmic in the attraction sphere; not to 
 mention the different leucins, the vacuolar juice, and 
 the various inclusions? And in the nucleus must we 
 not consider the nuclear juice, the substance of the
 
 THE SPECIFIC FORM. 2OI 
 
 chromosomes, and that of the nucleoles ? And is not 
 each of these probably a very complex mixture ? 
 
 However, it is to this mixture that we attribute the 
 possession of a form, in virtue of and by extension of 
 the principles of crystallization, which definitely teach 
 us that these mixtures cannot have form ; that form 
 is the attribute of pure bodies, and is only obtained 
 by the separation of the blended parts i.e., by a 
 return to homogeneity. There are therefore very 
 good reasons for hesitating before we transfer the 
 absolute principle of the dependence between 
 chemical form and composition, as some philo- 
 sophical biologists have done, from the physical 
 sciences where it is already subject to serious 
 restrictions to the biological sciences. 
 
 Le Dantec, however, has made this principle the 
 basis of his biological system. He therefore finds in 
 the crystal the model of the living being. He thus 
 gives a physical basis to life. 
 
 Is it a question in this system of explaining this 
 incomprehensible, this unfathomable mystery, which 
 shows the egg cell attracting to itself materials from 
 without and progressively building up that amazing 
 structure which is the body of the animal, the body of 
 a man, of any given man, of Primus, for example? 
 It is said that the substance of Primus is specific 
 His living substance is his own, special to him; and 
 that, too, from the beginning of the egg to the end of 
 its metamorphosis. It only remains to apply to this 
 substance the postulate, borrowed from crystallo- 
 graphy, of the absolute dependence of the nature of 
 substance on the form it assumes. The form of the 
 body of the animal, of the man, of Primus, is the 
 crystalline form of their living substance- It is the
 
 202 LIFE AND DEATH. 
 
 only form of equilibrium that this substance can 
 assume under the given conditions, just as the cube is 
 the crystallized form of sea salt, the only state of 
 equilibrium of chloride of sodium in slowly evaporated 
 sea water. Thus the problem of the living form is 
 reduced to the problem of the living substance, which 
 seems easier; and at the same time the biological 
 mystery is reduced to a physical mystery. It is clear 
 that this way of looking at things simplifies pro- 
 digiously and, we must add, simplifies far too much 
 the obscure problem of the relation of form to 
 substance, simultaneously in the two orders of science. 
 This may be summed up in a single sentence: 
 There is an established relation between the specific 
 form and the chemical composition: the chemical 
 composition directs and implies the specific form. 
 
 We need not now examine the basis of this opinion. 
 If it is nothing but a verbal simplification, a unifica- 
 tion of the language applied to the two orders of 
 phenomena, it implies an assimilation of the mechan- 
 isms which realize them. To the organogenic forces 
 which direct the building up of the living organisms 
 it brings into correspondence the crystallogenic forces 
 which group, adjust, equilibrate, and harmonize the 
 materials of the crystal. 
 
 When it is a question of the application of a 
 principle such as this, in order to test its legitimacy 
 we must always return to the experimental founda- 
 tions. Let us imagine, for example, a simple body, 
 such as sulphur, heated and brought to a state of 
 fusion that is to say, homogeneous, isotropic, in an 
 undisturbed medium the only change in which will 
 be a very gradual cooling down. These are the 
 typical crystallogenic conditions. The body would
 
 THE SPECIFIC FORM. 203 
 
 take a given crystalline form. It is from experiments 
 such as this that we derive the idea of a specific form 
 connected with a chemical constitution. 
 
 But in drawing this conclusion our logic is at fault. 
 The real interpretation suitable to this case, as in all 
 others, is that the specific form is suitable to the 
 substance, and also to the physical, chemical, and 
 mechanical conditions in which it is placed. And 
 the proof is that this same substance, sulphur, which 
 takes the prismatic form immediately after fusion, 
 will not retain that form, but will pass on to the 
 quite different octahedral form. 
 
 It is so with the specific form of the living being 
 that is to say, with the assemblage of its constituent 
 materials co-ordinated in a given system in a word, 
 with its organization. This is suitable to its sub- 
 stance, and to all the material, physical, chemical, 
 and mechanical conditions in which it is placed. This 
 form is the condition of material equilibrium cor- 
 responding to a very complex situation, to a sum of 
 given conditions. The chemical condition is only 
 one of these. And further, it is hardly proper to 
 speak of a " chemical substance " when we refer to an 
 astonishingly complex mixture which is in addition 
 variable from one point to the other of the living 
 body. When we thus reduce phenomena to their 
 original signification, false analogies disappear. To 
 say with Le Dantec that the form of the greyhound 
 is the condition of equilibrium of the "greyhound 
 chemical substance " is saying much ; and too much, 
 if it means that the body of the greyhound has a 
 substance which behaves in the same way as homo- 
 geneous, isotropic masses like melted sulphur and 
 dissolved salt It were better to say much less, if it
 
 204 LIFE AND DEATH. 
 
 means, as it will in the minds of the physiologists, 
 that the body of the greyhound is the condition of 
 equilibrium of a heterogeneous, anisotropic, material 
 system, subjected to an infinite number of physical 
 and chemical conditions. 
 
 The idea of connecting form, and by that we mean 
 organization, with chemical composition did not arise 
 in the minds of chemists or physiologists. Both have 
 expressed themselves very clearly on this point. 
 
 "We must distinguish," said Berthelot, "between 
 the formation of the chemical substances, the assem- 
 blage of which constitutes organized beings, and the 
 formation of the organs themselves. This last problem 
 does not come into the domain of chemistry. No 
 chemist will ever claim to have formed in his laboratory 
 a leaf, a fruit, a muscle, or an organ. . . . But chemistry 
 has a right to claim that it forms direct principles 
 that is to say, the chemical materials which constitute 
 the organs." And Claude Bernard in the same way 
 writes: "In a word, the chemist in his laboratory, 
 and the living organism in its apparatus, work in the 
 same way, but each with its own tools. The chemist 
 can make the products of the living being, but he 
 will never make the tools, because they are the result 
 of organic morphology." 
 
 2. THE ACQUISITION AND RE-ESTABLISHMENT 
 OF THE SPECIFIC FORM. 
 
 Acquisition of the Typical Form. The acquisition 
 of the typical form in the living being is the result of 
 ontogenic work which cannot be examined here. In 
 the elementary being, the plastid, this work is blended
 
 THE SPECIFIC FORM. 2O5 
 
 with the work of nutrition. It is directtd mtlriticm. 
 It consists of a simple increase from the moment the 
 element is born by the division of an anterior dement; 
 and of a necessarily restricted differentiation. It is a 
 rudimentary embryogeny. In the complex being, 
 metazoan or metaphyte, the organism is constituted!,, 
 starting from the egg, by the growth, by the biporti- 
 tion of the elements, and their differentiation, accom- 
 plished in a ryrtain direction and in conformity with 
 a given plan. This, again, is directed nutrition, but 
 here the embryogeny is complex. The directing plan 
 of operations is no doubt the consequence of the 
 material conditions realized each moment in the 
 
 ~ ' ~ ':. ". . ~ . 
 
 Normal Regeneration. Not only do living beings 
 themselves construct their typical architecture, but 
 they re-establish it and continually reconstitute it, 
 according as accidents, or even ordinary circumstances, 
 tend to destroy it ; in a word, they become rejuvenes- 
 cent. This regeneration consists in the reformation 
 of the parrs that are altered or carried away in the 
 normal play of life, or by the accidents which disturb 
 its course. 
 
 Thus there is a normal physiological regeneration^ 
 which is, so to speak, the prolongation of the onto- 
 genesis /., of the work of fonnation of the individual 
 We have examples in the reconstitntion of the skin 
 of mammals; in the throwing off of the epidermic 
 products constantly used up in their superficial and 
 *"*t i *f jMfts and regenerated in ffc^i** deeply-seated 
 parts; in the loss and the renewal of teeth at the 
 first dentition and in certain fish in the fact of 
 successive dentitions; in the periodical renewal of 
 the integument in the larva; of insects, and in the
 
 206 LIFE AND DEATH. 
 
 crustaceae; and finally in the destruction and the 
 neo-formation of the globules of the blood of verte- 
 brates, of the glandular cells, and of the epithelial 
 cells of the intestine. 
 
 Accidental Regeneration in Protozoa and Plastids. 
 There is also an accidental regeneration which more or 
 less perfectly renews the parts that are lost. This 
 regeneration has its degrees, from the simple cicatriza- 
 tion of a wound to the complete reproduction of the 
 part cut off. It is very unequally developed in 
 zoological groups even when they are connected. 
 In the elementary monocellular beings i.e., in the 
 anatomical elements and in the protozoa, the experi- 
 ments in merotomy, i.e., in partial section, enable us 
 to appreciate the extent of this faculty of regenera- 
 tion. These experiments, inaugurated by the re- 
 searches of Augustus Waller in 1851, were repeated 
 by Gruber in 1885, continued by Nussbaum in 1886, 
 Balbiani in 1889, Verworn in 1891, and have been 
 reproduced by a large number of observers. They 
 have shown that the two fragments cicatrize, and are 
 repaired, building up an organism externally similar 
 to the primitive organism, but smaller. The two new 
 organic units do not, however, behave in the same 
 way. That which retains the nucleus possesses the 
 faculty of regeneration, and of living as the primitive 
 being lived. The protoplasmic fragment, which does 
 not contain the nucleus, cannot rebuild this absent 
 organ; and though it has functional activity in most 
 respects, just as the nucleated fragment, yet it is 
 distinguished from it in others of great importance. 
 The anucleated fragment of an infusorian behaves as 
 the nucleated, and as the whole animal so far as the 
 movements of the body, the cilia, prehension of food,
 
 THE SPECIFIC FORM. 207 
 
 evacuation of faeces, and the rhythmical contrac- 
 tion of the pulsatile vesicules are concerned. But 
 Balbiani's researches in 1892 have shown us that 
 secretion, complete regeneration, and the faculty of 
 reproduction by fission can take place only in the 
 nucleated fragment i.e., in the nucleus. 
 
 Accidental Reproduction in the Aletazoa. Among 
 multicellular beings the faculty of reproduction is met 
 with in the highest degree in plants, where we find it 
 in the process of propagation by slips. In animals it 
 is the most marked in Ccelenterata. Trembley's 
 experiments are a striking instance. We know that 
 when the hydra is cut into tiny pieces it reproduces 
 exactly as many complete beings. Among the 
 worms, Planaria afford a similar example. Every 
 fragment, provided its volume is not less than a tenth 
 of that of the whole, can reproduce a complete, entire 
 being. The snail can produce a large part of its head, 
 including the tentacles and the mouth. Among the 
 Tritons and the Salamanders the faculty of regenera- 
 tion reproduces the limbs, the tail, and the eye. In 
 the Frog family, on the contrary, the work of re- 
 generation does not go beyond cicatrization, and it is 
 the same with Birds and Insects. 
 
 It is really startling to see in a vertebrate like the 
 Triton the stump of an arm with its fragment of 
 humerus reproducing the forearm and the hand in all 
 their complexity, with their skeleton, blood vessels, 
 nerves, and teguments. We say that the limb has 
 budded, as if there were a germ of it which develops 
 like the seed of a plant, or as if each transverse portion 
 of the limb, each slice, so to speak, could re-form the 
 slice that follows. 
 
 The mechanism of generation and that of regenera-
 
 208 LIFE AND DEATH. 
 
 tion alike raise problems of the highest importance. 
 Does the part become regenerated just as it was 
 formed at first ? Does the regeneration repeat the 
 ontogeny? Is it true that a lost organ is never re- 
 generated (the kidney for instance) ? Does the 
 symmetrical organ enjoy a compensating and hyper- 
 trophic development, as Ribbert has asserted ? And 
 further, if the organ be removed and transplanted to 
 another position, can it be grafted there, as Y. Delage 
 maintains? These are very important questions; but 
 if we dwell upon them, we shall be diverted from our 
 immediate object. Our task is to look at these facts 
 from the point of view of their significant and char- 
 acteristic meaning in vitality. Flourens invoked on 
 their behalf the intervention of vital forces, plastic 
 and morpJioplastic. But, as we shall see later, these 
 phenomena of cicatrization, of reparation, of re- 
 generation, these more or less complete efforts for 
 the re-establishment of the specific form, although 
 they are found in all living beings in different degrees, 
 are not exclusively confined to them. We find them 
 again in some representatives of the mineral world 
 in crystals, for instance.
 
 CHAPTER VI. 
 
 NUTRITION. 
 
 FUNCTIONAL ASSIMILATION. FUNCTIONAL DESTRUC- 
 TION. ORGANIC DESTRUCTION. ASSIMILATING 
 SYNTHESIS. 
 
 The extreme importance of nutrition i. Effect of vital 
 activity Destruction or growth Distinction between the 
 living substance and the reserve-stuff mingled with it 
 Organic destruction Destruction of reserve-stuff De- 
 struction of living matter Growth of living matter 
 2. The two categories of vital phenomena Foundations 
 of the idea of functional destruction The two kinds of 
 phenomena of vitality Criticism of Claude Bernard 
 Current views Criticism of Le Dantec's new theory of 
 life. 3. Correlation of the two kinds of vital facts Law 
 of connection Contradictions in the new theory. 4. The 
 characteristics of nutrition Its definition Its permanence 
 Erroneous idea of the vital vortex Formative assimilation 
 of reserve-stuff Formative assimilation of protoplasm 
 Death, real and apparent. 
 
 The Immense Importance of Nutrition. We new 
 come to the important feature of vitality. All other 
 characteristics of living matter, its unstable equilibrium, 
 its chemical and anatomical organization, the acquisi- 
 tion and the maintenance of a typical form, are only 
 secondary properties, so to speak, subordinate with 
 reference to nutrition. Generation itself is only a 
 mode. Nutrition is the essential attribute of life. It 
 is life itself. 
 
 209
 
 210 LIFE AND DEATH. 
 
 Before we define it a few preliminary explanations 
 are necessary. 
 
 The most striking thing in living matter is its 
 growth. An animal, a vegetable, is something which 
 is first more or less minute, and which grows. Its 
 characteristic is to expand from the spore, the seed, 
 the slip, the egg it grows. 
 
 Whether we are dealing with a cellular element, a 
 plastid, or a complex being, their condition is the 
 same in this respect. No doubt when the animal or 
 plant has reached a certain stage of development its 
 growth is stopped, and for a more or less lengthy 
 period it remains in the adult stage, in what seems to be 
 equilibrium. But even then there is no check in the 
 manufacture of living matter; there is only a com- 
 pensation between its production and its destruction. 
 
 It is important to reduce to order the ideas on this 
 important subject, which at present are confused, 
 inconsistent, and contradictory. In biology grievous 
 confusion reigns. 
 
 i. EFFECT OF THE VITAL ACTIVITY. 
 DESTRUCTION OR GROWTH? 
 
 Distinction between the Living Substance and tJie 
 Reserve-stuff mingled ivith it. The physiology of 
 nutrition has given rise to a vast body of research 
 during the last half-century. Physiological schools, 
 masters and pupils, such as the school at Munich 
 under Voit and Pettenkofer, Pfltiger's at Bonn, 
 Rubner's, and those of Zuntz and von Noorden at 
 Berlin, and a large number of zootechnical and agri- 
 cultural laboratories through the whole world have for
 
 NUTRITION. 211 
 
 years past been engaged in analyzing ingesta and 
 egesta, in drawing up schedules of nutrition, in order 
 to determine the course of decomposition and re- 
 constitution of the living material. 
 
 If I were asked what, in my opinion, is the most 
 general result of all this labour, I would reply that it 
 has affirmed and corroborated the important distinc- 
 tion which must be drawn between living substance, 
 properly so called, and reserve-stuff. The latter, the 
 reserve-stuff of albuminoids, carbohydrates, and fats, 
 are so intimately intermingled with the living sub- 
 stance that they are in most cases very difficult to 
 distinguish from it 
 
 Organic Destruction. A second point, which is 
 placed equally beyond doubt, is that the vital func- 
 tional activity is accompanied by a destruction of the 
 immediate principles of the organism, in the direction 
 of their simplification. This functional destruction 
 cannot be doubted in the case of differentiated organs 
 in which the functional activity is evident, inter- 
 mittent, and in some measure distinct from the other 
 vital phenomena which take place in them. For 
 example, in the case of contracting muscles the 
 respiratory carbonic acid and urinary carbon are the 
 irrefutable proofs of this destruction : weak in repose, 
 abundant during activity, and in proportion to it 
 There can be no doubt on this point The truth 
 laid down by Claude Bernard under the name of 
 the law of functional destruction has been doubly 
 consecrated by experiment and theory. According 
 to the energetic theory, in fact, mechanical and 
 thermal energies manifested in the vital functional 
 activity can only have their source in the chemical 
 energy set free by the destruction of the immediate
 
 212 LIFE AND DEATH. 
 
 principles of the organism, reduced to a lower degree 
 of complexity. 
 
 Destruction of Reserve-stuff. But now the disagree- 
 ment begins. What are these decomposed, destroyed 
 principles ? Do they belong to the cellular reserve- 
 stuff or to the living matter properly so called ? 
 There is no doubt that most of them belong to the 
 reserve-stuff. For example, this is especially true of 
 glycogen, which is consumed in muscular contraction 
 just as coal is consumed in the furnace of the loco- 
 motive ; and glycogen is a reserve-stuff of muscle. 
 These reserve-stuffs destroyed in the functional 
 activity can be built up again only during repose. 
 
 But it is not yet certain whether the living 
 matter itself, the active protoplasm, the muscular 
 protoplasm, takes part in this destruction, whether it 
 provides it with elements. Experiments have proved 
 contradictory. Experimenters have isolated the nitro- 
 genous wastes (urea) after muscular labour, and they 
 have compared them with the wastes of the period of 
 repose. These nitrogenous wastes bear witness to the 
 destruction of albuminoid substances, and the latter 
 are the constituent principles of living matter. If 
 under conditions of sufficient alimentation the mus- 
 cular functional activity involves more nitrogenous 
 waste, i.e., a greater destruction of albuminoids, it 
 might be supposed that the living material properly 
 so called has been used up and destroyed for its 
 own purposes. (And here again there might be a 
 reserve-stuff of albuminoids, distinct from the living 
 protoplasm itself, and more or less incorporated 
 with it.) 
 
 But experiment so far has not given decisive results. 
 The latest experimental researches, such as those of
 
 NUTRITION. 213 
 
 I go Kaup, of Vienna, which date from 1902, tell us as 
 uncertain a tale as their predecessors. The increase 
 in the destruction of albumen has not been constant ; 
 the conditions of the observations do not justify our 
 making an assertion either pro or con. 
 
 Destruction of Living Matter. As no certain 
 answer is supplied by experiment, theory intervenes 
 and gives two conflicting answers. The majority of 
 physiologists are inclined to believe in the destruction 
 of tJu Ircing substance as the result of its own func- 
 tional activity. The functional activity would there- 
 fore destroy not only the reserve-stuff, but also the 
 protoplasmic material. This is the current view. 
 Only this opinion is strongly challenged by the 
 positive teaching of science. It is certain that this 
 material, in the muscle, is but little attacked, if it 
 is attacked at all We have seen above that the 
 physiologists, with Pfliiger and Chauveau, are agreed 
 on this point. The vital functional activity in par- 
 ticular is destructive to the reserve-stuffs. It does 
 not destroy them much; it destroys the organic 
 material still less. Both would be repaired in func- 
 tional repose 
 
 Growth of Living Matter. The second assertion is 
 diametrically opposed to this. Not only, says Le 
 Dantec, is the muscle not destroyed in the functional 
 activity, but it grows. Contrary to universal opinion, 
 the protoplasmic material increases by activity, and it 
 is destroyed in repose. There would thus be a 
 general law the law of functional assimilation. " A 
 cell of brewers' yeast when introduced into a sugared 
 must makes this must ferment, and at the same time, 
 so far from destroying it, it increases it Now, the 
 fermentation of the must is exactly the same as the
 
 214 LIFE AND DEATH. 
 
 functional activity of the yeast." It is, says the same 
 author, a mistake to believe that the phenomena of 
 functional activity, of vital activity, only takes place 
 at the price of organic destruction. Here, then, are 
 these two competing views. They are not so very far 
 apart as a matter of fact, since the question at issue is 
 one of deciding between a slight destruction and a 
 slight growth, but theoretically they are strongly 
 opposed. Moreover, they are arbitrary, and experi- 
 ment has not decided between them. 
 
 2. THE TWO CATEGORIES OF VITAL PHENOMENA. 
 
 Foundation of tJie Idea of Functional Destruction, 
 Claude Bernard. The doctrine of functional de- 
 struction has been laid down with remarkable power 
 by Claude Bernard. But the terms in which he has 
 expressed it in a measure betray the thoughts of the 
 great physiologist, or, at any rate, overstep the 
 immediate fact he had in view. " The phenomena 
 of destruction are very obvious. When movement is 
 produced, when the muscle contracts, when volition 
 and sensibility are manifested, when thought is 
 exercised, when the gland secretes, then the sub- 
 stance of the muscles, of the nerves, of the brain, oi 
 the glandular tissue, becomes disorganized, destroyed, 
 and consumed. So that every manifestation of a 
 phenomenon in the living being is necessarily con- 
 nected with an organic destruction." To Claude 
 Bernard organic destruction is a truth. To Le Dantec 
 it is an error. Which is right? Clearly Claude 
 Bernard. He bases his conviction on the analyses 
 of the materials excreted in the process of physio-
 
 NUTRITION. 215 
 
 logical work. The excreta bear witness to a certain 
 organic demolition. Generalizing this teaching of 
 experiment the illustrious biologist divined the 
 fundamental law of energetics before the idea of 
 energetics had made much way in France. Every 
 act which expends energy, which produces heat or 
 motion, any manifestation whatever that may be 
 looked upon as an energetic transformation, neces- 
 sarily expends energy, and that energy is borrowed 
 from the substance of the organism. These sub- 
 stances are simplified, broken up, and destroyed. 
 Now the functional activity of the muscle produces 
 heat and movement in warm-blooded as well as in 
 cold-blooded animals. The functional activity of 
 the glands produces heat, as has been shown by the 
 celebrated experiments of C. Ludwig on the salivary 
 secretion, and as is also shown by the study of thermal 
 topography in the vertebrates. The functional activity 
 of the nerves and the brain produces a slight quantity 
 of electricity and heat, as most observers have agreed. 
 The functional activity of the electrical and of the 
 photic apparatus also expends energy. Finally, the 
 eye which receives the photic impression destroys the 
 purple matter of the retina, and that purple matter, 
 as we well know, is recuperated in the dark during 
 the repose of the organ. Everything that is expressed 
 objectively, everything that is a phenomenon in the 
 living being with the exception of growth and 
 formation, which are generally slow phenomena, and 
 of which we can only get an idea by the comparison 
 of successive states all these energetic manifestations 
 suppose a destruction of organic matter, a chemical 
 simplification, the source of the energy manifested 
 And that is why material destruction does not merely 
 
 ID
 
 2l6 LIFE AND DEATH. 
 
 coincide with functional activity, but is its measure 
 and expression. 
 
 The Two Kinds of Phenomena of Vitality. Another 
 point on which Claude Bernard is right and his 
 opponent is wrong is not less fundamental. What 
 are we to understand by functional phenomena ? 
 This is the very point at issue. Now, in the mind of 
 physiologists, this expression has a perfectly definite 
 meaning. It is not so with Le Dantec. Physiologists 
 who have studied animals rather high in organization 
 in which the differentiation of phenomena enables 
 us to grasp the fundamental distinction have readily 
 recognized that the phenomena of living beings are 
 divided into two categories. There are some which 
 are intermittent, alternative, which take place, or grow 
 stronger at certain moments, but which cannot be 
 continuous they are the functional acts ; there are 
 others in which this characteristic of explosives, 
 energetic expenditure and intermittence, do not 
 appear they are, in general, the nutritive acts. The 
 muscle which contracts shows functional activity. It 
 has an activity and a repose. During this apparent 
 repose we must not say that it is dead ; it has a life, 
 but that life is obscure as far as the salient fact of 
 functional movement is concerned. The salivary 
 gland which throws up waves of saliva when the food 
 is introduced and masticated in the mouth, or when 
 the chord of the tympanum is at work, is in a state of 
 functional activity ; this is the salient phenomenon. 
 But before, though nothing, absolutely nothing, was 
 flowing through the glandular canal, yet the gland 
 was not reduced to the condition of a dead organ : it 
 was living a more obscure, a less evident life. The 
 microscopical researches of Kiihne, Lea, and Langley,
 
 NUTRITION. 217 
 
 now universally verified, show us that during this 
 time of apparent repose the cells were loading up 
 their granulations and getting ready the materials of 
 secretion, as just now the muscle at rest was accumu- 
 lating glycogen and the reserve-stuff which are to be 
 expended and destroyed in contraction. Similarly, 
 with regard to the functional activity of the other 
 glands, of the brain, etc. Claude Bernard was, there- 
 fore, perfectly right, when he took as his model the 
 chemists who distinguished between exothermic and 
 endothermic reactions, and who classed the pheno- 
 mena of life into two great divisions : those of 
 functional activity, and those of functional repose. 
 
 ist TJie phenomena of functional activity "are 
 those which 'leap to the eyes,' and by which we 
 are inclined to characterize life. They are con- 
 ditioned by the effects of wear and tear, of chemical 
 simplication, and of the organic destruction which 
 liberates energy." And it must be so, because these 
 functional manifestations expend energy. These 
 phenomena, which are the most obvious, are also the 
 least specific phenomena of vitality. They form 
 part of the general phenomenality. 
 
 2nd. The plienomena which accompany functional 
 repose correspond to the building up of the reserve- 
 stuff destroyed in the preceding period, to the organiz- 
 ing synthesis. The latter remains " internal, silent, 
 concealed in its phenomenal expression, noiselessly 
 gathering together the materials which will be ex- 
 pended. We do not see these phenomena of 
 organization directly. The histologist and the 
 embryogenist alone, following the development of 
 the element or of the living being, sees the changes 
 and the phases which reveal this silent effort. Here
 
 2l8 LIFE AND DEATH. 
 
 is a store of substance ; there, the formation of 
 an envelope or a nucleus ; there, a division or 
 multiplication, a renewal." This type of phenomena 
 is the only type which has no direct analogues : 
 it is peculiar, special to the living being : what 
 is really vital is this evolutive synthesis. Life is 
 creation. 
 
 Criticism of Claude Bernard. All this is perfectly 
 true. Thirty years of the most intensive scientific 
 development have run by since these lines were 
 written, and have not essentially changed the ideas 
 therein expressed. His work in its broad lines 
 remains intact Does that imply, however, that 
 everything is perfect in detail and expression, and 
 that there is no reason for making it more precise or 
 for giving it fresh form ? No doubt this is not so. 
 Although Claude Bernard contributed to establish 
 the essential distinction between the real living 
 protoplasm and the materials of reserve-stuff which 
 it contains, he has not drawn a sufficiently clear 
 distinction between what belongs to each of the 
 categories. He has not specified, in relation to 
 organic destruction, what bearing it has on the 
 organic materials of reserve-stuff. Sometimes he uses 
 the term " organic destruction," which is correct, and 
 sometimes "vital destruction," which is of doubtful 
 import Further, he employs an obscure and 
 paradoxical formula to characterize the obvious but 
 nevertheless not specific phenomena of organic 
 destruction, and he says : "life is death.". /Xrtu/U' - 
 
 Current Views. Nowadays, if I may express a 
 personal opinion on this important distinction be- 
 tween functional activity and functional repose, I 
 should say that after having distinguished between
 
 NUTRITION. 2ig 
 
 the two categories of phenomena we must try to 
 correlate them. We must try to discover, for 
 instance, what there is in common between the 
 muscle in repose and the muscle in contraction, and 
 to perceive in the muscular toitus a kind of bridge 
 thrown between these two conditions. The functional 
 activity would be uninterrupted, but it would have its 
 degrees of activity. The muscular ton us would be 
 the permanent condition of an activity which is cap- 
 able only of being considerably raised or lowered. 
 Similarly for the glandular functional activity ; the 
 periods of charge must be connected with the periods 
 of discharge. In a word, following the constant path 
 of the human mind in scientific knowledge, after 
 having drawn the distinctions that are necessary to 
 our understanding of things, we must obliterate them. 
 After having dug our ditches we must fill them up 
 again. After having analyzed we must synthesize. 
 The distinction between the phenomena of functional 
 activity and the phenomena of functional repose or 
 purely vegetative and nutritive activity, though only 
 valid in the case of a provisional and approximate 
 truth, none the less throws light on the obscure 
 regions of biology. 
 
 The succession of energy and repose, of sleep and 
 awakening, is a universal law, or at least a very 
 general law, connected with the laws of energetics. 
 The heart, the lungs, the muscles, the glands, the 
 brain obey in the most obvious manner this obligation 
 of rhythmical activity. The reason is clear. It is 
 because the functional activity involves what is 
 generally a sudden expenditure of energy, and this 
 has to be replaced by what is generally a slow 
 process of reparation. Functional activity is an
 
 220 LIFE AND DEATH. 
 
 explosive destruction of a chemical reserve which is 
 built up again more or less slowly. 
 
 Criticism of Le D anted s " Ne^v Theory of Life? 
 Let us now examine the antithesis of Claude 
 Bernard's views. There are evidently rudimentary 
 organisms in which the differentiation of the two 
 categories of phenomena is but little marked ; in 
 which, apart from the movement, it is impossible to 
 recognize intermittent, functional activities clearly 
 distinct from morphogenic activity. It is not in this 
 domain of the indistinct that \ve must seek the 
 touchstone of physiological distinctions. Clearly, we 
 must not choose these elementary plastids to test 
 the doctrine of functional assimilation and functional 
 destruction. But is not this exactly what Le Dantec 
 did when he began his researches on brewers' yeast? 
 When we try to examine things, we must choose the 
 conditions under which they are differentiated, and 
 not those in which they are confused. And this is 
 why, in the significant words of Auguste Comte, " the 
 more complex living beings are, the better known 
 they are to us." The philosopher goes still farther 
 in this direction, and adds "directly it is a question 
 of the characteristics of animality we must start from 
 the man, and see how those characteristics are little 
 by little degraded, rather than start from the sponge 
 and endeavour to discover how these characteristics 
 are developed. The animal life of the man assists 
 us to understand the life of the sponge, but the 
 converse is not true." 
 
 When, moreover, we consider a vegetable organism 
 such as yeast, which derives its energy, not from 
 itself, not from the potential chemical energy of its 
 reserve- stuff, but directly from the medium that is
 
 NUTRITION. 221 
 
 to say, from the potential chemical energy of the 
 compounds which form its medium of culture, we 
 then find ourselves in the worst possible situation for 
 the recognition of organic destruction. Further, it is 
 doubly wrong to assert that in so ill-chosen a type 
 the functional phenomena do not result from an 
 organic destruction for at first there are no very 
 distinct functional phenomena here and, in the second 
 place, there certainly is organic destruction. The 
 phenomena of the morphogenic vitality detected in 
 the yeast are the exact concomitants, or the results, 
 of the destruction of an organic compound, which in 
 this case is sugar. The yeast destroys an immediate 
 principle, and this is the point of departure of its vital 
 manifestations ; only, it has not, as a preliminary, 
 clearly incorporated and assimilated this principle. 
 When, therefore, the functional phenomena are 
 effaced and disappear, we none the less find pheno- 
 mena of destruction of organic compounds which are 
 in a measure, a preface to the phenomena of growth. 
 This is what happens in the case of brewers' yeast : 
 and here, again, the two categories of facts exist 
 Once more, we find, in the first place, the phenomena 
 of destruction (destruction of sugar, reduced by 
 simplification to alcohol and carbonic acid) pheno- 
 mena which this time no longer respond to obvious 
 functional manifestations ; and, in the second place, 
 the phenomena of chemical and organogenic synthesis, 
 corresponding to the growth of the yeast and the 
 multiplication of its protoplasm. The former are no 
 longer detected, as we have just said, by striking 
 manifestations. However, it is not true that every- 
 thing which is visible and which may be isolated 
 outside the activity of the yeast is part of those
 
 222 LIFE AND DEATH. 
 
 phenomena. The boiling of the juice or the mash, 
 the heat given off by the copper, all this phenomenal 
 apparatus is but the consequence of the production of 
 the carbonic acid and of its liberations i.e., the 
 consequence of the act of destruction of the sugar. 
 Here is organic destruction with its energetic 
 manifestations ! 
 
 This example of the life of brewers' yeast, of the 
 saccharomyces, specially chosen by Le Dantec as 
 being absolutely clear and giving the best illustration 
 of his argument, contradicts him at every point. The 
 general thesis of this vigorous thinker is that we 
 cannot distinguish between the two parts of the vital 
 act, organic destruction, and assimilating synthesis ; 
 that these two acts are not successive ; that they give 
 rise to phenomenal manifestations equally evident, 
 apparent, or striking. Now, in the case of yeast, the 
 phenomenon of destruction is clearly distinct from 
 that of the assimilating synthesis which multiplies 
 the substance of the saccharomyces. In fact, the 
 action is realized by means of an alcoholic diastase 
 manufactured by the cell ; and Biichner succeeded in 
 isolating this alcoholic ferment which splits up the 
 sugar into alcohol and carbonic acid, and also in vitro 
 and in vivo, makes the vat boil and heats the liquid. 
 All the yeast is at work at once, says M. Dantec. 
 No, and this is the proof. 
 
 And, further, Pasteur himself, who had shown the 
 relation of the decomposition of the sugar to the fact 
 of the growth of the yeast and of the production 
 of accessory substances such as succinic acid and 
 glycerine, always referred to correlation between these 
 phenomena. The destruction of the sugar is the 
 correlative of the life of the yeast. This was his
 
 NUTRITION. 223 
 
 favourite formula. It never entered his head that 
 there could be a confusion instead of a correlation, 
 and that there might be only one and the same act, 
 the phases of which would be indistinguishable. 
 This unfortunate idea, which was fated to be so 
 rapidly contradicted, is due to Le Dantec. Far 
 from it being the case, Pasteur had distinguished 
 the ferment function from the life of the yeast 
 According to him, the yeast may exist sometimes as 
 a ferment and sometimes otherwise. 
 
 3. CORRELATION OF Two ORDERS OF 
 VITAL FACTS. 
 
 It is this correlation between acts distinct in them- 
 selves but usually connected that was announced by 
 Claude Bernard. And, mitabile dictu and this is the 
 natural outcome of the perfect sanity of mind of this 
 great physiologist it happens that not only Pasteur's 
 researches, but the development of a new science, 
 Energetics, and Btichner's discovery lend support to 
 his views, and that, too, in a field where one would 
 have thought they had no application. Le Dantec is 
 wrong when he declares that these ideas only apply to 
 vertebrates. ''It is clear," he says on several occa- 
 sions, " that the author has in view the metazoa and 
 even the vertebrates." Well .' no. All that is general, 
 universally applicable, and universally true. So that 
 there are two orders of distinct phenomena ener- 
 getically opposed and certainly connected. \Ve need 
 only repeat Claude Bernard's own words quoted by 
 Le Dantec in order to confute them. 
 
 Law of Connection of Two Orders of Vital Facts. 
 "These phenomena [of organic destruction and of
 
 224 LI FE AND DEATH. 
 
 assimilating synthesis] are simultaneously produced 
 in every living being, in a connection which cannot 
 be broken. The disorganization or dissimilation uses 
 up living matter [by this we must understand the 
 reserve-stuff, as will be seen later on in the quotation] 
 in the organs in function: the assimilating synthesis 
 regenerates the tissues; it gathers together the re- 
 serve-stuff which the vital activity must expend. 
 These two operations of destruction and renovation, 
 inverse the one to the other, are absolutely connected 
 and inseparable, in this sense at any rate, that de- 
 struction is the necessary condition of renovation. 
 The phenomena of functional destruction are them- 
 selves the precursors and the instigators of material 
 regeneration, of the formative process which is silently 
 going on in the intimacy of the tissues. The losses 
 are repaired as they take place; and equilibrium being 
 re-established as soon as it tends to be broken, the 
 body is maintained in its composition." 
 
 It is perfectly right and wise to say with Claude 
 Bernard that the two orders of facts are successive, 
 and that one is normally the inciting condition of the 
 other. The possibility of the development of the 
 yeast when fermentation fails, and the weakness of 
 this development on the other hand under these con- 
 ditions, are an excellent proof of this. The one proves 
 the essential independence of the two orders of facts, 
 the other the inciting and provoking virtue of the first 
 relatively to the second. The experimental truth is 
 thus expressed with a minimum of uncertainty. We 
 know the facts which led Le Dantec to formulate his 
 law of functional assimilation namely, that the 
 functional activity is useful or indispensable to the 
 growth of the organ ; that the organs which are
 
 NUTRITION. 225 
 
 functionally active grow, and those which do not act 
 become atrophied. We are only expressing the facts 
 when we say that the organic destructions that go on in 
 the living being (whether at the expense of its reserve- 
 stuff or at the expense of its medium, or whether it be 
 even slightly at the expense of the plastic substance 
 itself) are the antecedent, the inciting agent or the 
 normal condition of the chemical and organogenic 
 syntheses which create the new protoplasm. 
 
 On the other hand, we are wrong if we hold with 
 Le Dantec that instead of two chemical operations 
 there is only one, that which creates the new proto- 
 plasm. The obvious destruction is neglected ; it is 
 deliberately passed over. He does not see that it is 
 necessary to liberate the energy employed in the 
 construction, by complication, of this highly complex 
 substance which is the new protoplasm. He really 
 seems to have made up his mind not to analyze the 
 phenomenon. If we decline to admit that to the first 
 act of functional destruction succeeds a second, 
 assimilation or organogenic synthesis, we are look- 
 ing at elementary beings, in which the succession 
 cannot be grasped, as we look on brewers' yeast 
 We not only mean that the morphogenic assimilation 
 results from the functional activity ; we mean that it 
 results from it directly, immediately, that it is the 
 functional activity itself. Experiment tells us nothing 
 of all this It shows us the real facts, the facts of the 
 destruction of an organic immediate principle, the 
 sugar, and the fact that an assimilating synthesis is 
 the correlative of this destruction. Besides, if it is 
 impossible in examples of this kind to exhibit the 
 succession, it is perfectly easy in beings of a higher 
 order. It is, then, clearly seen that the preliminary
 
 226 LIFE AND DEATH. 
 
 destruction of a reserve-stuff (and perhaps of a small 
 quantity of the living substance) precedes and con- 
 ditions the formation of a greater quantity of this 
 living matter in other words, the growth of the 
 protoplasm of the organ. 
 
 Contradictions in the New Theoty. Moreover, these 
 mistakes involve those who make them in a series of 
 inextricable contradictions. Here, for example, is 
 life; it is found, they say, in three forms: Life 
 manifested, or condition 1; latent life, or condition 
 3. So far this is the classical theory; but they add 
 a condition 2, which is what might be called patJio- 
 logical or incomplete life. This is defined by the 
 following characteristic: That its functional pheno- 
 mena are identical with those in the first form, but 
 that they are not accompanied by assimilation and by 
 protoplasmic growth. But since, they say, growth is 
 the chemical consequence of the functional activity, 
 since it is so to speak its metabolic aspect, since it is 
 confused w r ith it, and inseparable from it, by the 
 argument then it is contradictory and logically 
 absurd to speak of condition 2. It would be ac- 
 knowledging in the case of the anucleated merozoite, 
 for example, a functional activity unaccompanied by 
 assimilation, yet identical with the functional activity 
 which is accompanied by assimilation in the nucleated 
 merozoite. The general movement, that of the cilia, 
 the taking of food, the evacuation of the faeces, the 
 contraction of the pulsatile vacuoles, are the same. 
 And this fact is the best proof that this vital func- 
 tional activity (with the organic destruction which is 
 its energetic source) must be distinguished from the 
 assimilation which usually follows it, and which in 
 exceptional cases may not follow it.
 
 NUTRITION. 227 
 
 We shall carry this discussion no farther. We have 
 examined at some length Le Dantec's views, and we 
 have contrasted them with the doctrine which has 
 been current in general physiology since the time of 
 Claude Bernard, and this comparison does not turn 
 out quite to their advantage. It was inevitable that 
 the experimental and realistic spirit which inspired 
 the doctrine of the celebrated physiologist made his 
 work really too systematic. His formula, "life is 
 death," and the form he gave his ideas, are not always 
 irreproachably correct. They lend themselves at 
 times to criticism. Sometimes they require commen- 
 tary. These are errors of detail which Le Dantec 
 has summarized somewhat roughly. There is no 
 necessity to do this in his own case. We pay our 
 tribute to the clearness of his language, although \ve 
 believe the foundations of his system are false and 
 ill-founded. Their rigour is purely verbal. Their 
 external qualities, their careful arrangement are well 
 adapted to the seduction of the systematic mind 
 prepared by mathematical teaching. This new theory 
 of life is presented with pedagogic talent of the 
 highest order. We think we have shown that the 
 foundations are entirely fallacious, in particular the 
 following: Vital condition Xo. 2 3 ; the confusion be- 
 tween functional activity and assimilating synthesis ; 
 the so-called absolute connection between morpho- 
 geny and chemical composition ; the fundamental 
 distinction between elementary life and individual life. 
 
 4. CHARACTERISTICS OF NUTRITION. 
 
 Definition of Nutrition. As we have just seen, the 
 organism is the scene of chemical reactions of two
 
 228 LIFE AND DEATH. 
 
 kinds, the one destructive and simplifying, the other 
 synthetic, constructive, or assimilating. This totality 
 of reactions constitutes nutrition. Hence the two 
 phases that it is convenient to consider in this func- 
 tion assimilation and disassimilation. This twofold 
 chemical movement or metabolism corresponding to 
 the two categories of vital phenomena, of destruction 
 (catabolism) and of synthesis (anabolism) is therefore 
 the chemical sign of vitality in all its forms. But it 
 is clear that disassimilation or organic destruction, 
 which is destined to furnish energy to the organism 
 for its different operations, reappears in the plan of 
 the general phenomena of nature. It is not specific- 
 ally vital in its principle. Assimilation, on the other 
 hand, is in this respect much more characteristic. 
 
 To some physiologists nutrition is only assimila- 
 tion. Of the two aspects of metabolism they consider 
 only one, the most typical, Ad-similare, to assimilate, 
 to restore the substance borrowed from the ambient 
 medium, the alimentary substances, similar to living 
 matter, to make living matter of them, to increase 
 active protoplasm this is indeed the most striking 
 phenomenon of vitality. To grow, to increase, to 
 expand, to invade, is the law of living matter. 
 Assimilation, nutrition in its essentials, is, according 
 to the definition of Ch. Robin, "the production by the 
 living being of a substance identical with its own." 
 It is the act by which the living matter, the proto- 
 plasm of a given being, is created. 
 
 Permanence in Nutrition. Nutrition presents one 
 quite remarkable character permanence. It is a vital 
 manifestation, a property if we look at it in the cell, 
 in the living substance, a function if we consider it in 
 the animal or in the plant as a whole, which is never
 
 NUTRITION. 229 
 
 arrested Its suspension involves ipso facto ihe sus- 
 pension of life itself. It is, in the words of Claude 
 Bernard, that property of nutrition " which, as long as 
 it exists in an element, compels us to believe that this 
 element is alive, and which, when it is absent, compels 
 us to believe that it is dead. It dominates all others 
 by its generality and its importance. In a word, it is 
 the absolute test of vitality." 
 
 Biological Energetics shows the Importance of 
 Nutrition* We have indicated in advance the reason 
 of its importance, showing that its two phases, dis- 
 assimilation and assimilation, are the energetic 
 condition of the two kinds of vital phenomena 
 which we can distinguish. 
 
 Nutrition is a manufacture of protoplasm at the 
 expense of the materials of the cellular ambient 
 medium, which are assimilated />., made chemically 
 and physically similar to living matter and to the 
 reserves it stores up. This operation, which is 
 peculiarly chemical, is therefore indicated by the 
 borrowing of materials from the external world, a 
 borrowing which is always going on. because the 
 operation is permanent, and, let me add, because of 
 the continual rejection of the waste products of 
 this manufacture. Our formula is : Nutrition is a 
 chemistry which persists. 
 
 The Idea of the Vital Vortex is Erroneous. Here 
 the effect has hidden the cause from the eyes 
 of the biologists. They have been struck by the 
 incessant entry and exit, by the never-ceasing passage, 
 by the cycle of matter through the living being 
 without guessing its why and wherefore ; and they 
 have taken as a picture of the living being a vortex 
 in which the essential form is maintained while the
 
 230 LIFE AND DEATH. 
 
 matter, which is accessory, flows on without a check. 
 This is Cuvier's vital vortex. But for what purpose 
 is this circulating matter used ? They thought that 
 it was employed entirely for the reconstitution of 
 the living substance, continually and inevitably de- 
 stroyed by the vital Minotaur. 
 
 Destruction of Reserve- stuff. Here again there is 
 a mistake. Really living substance is but little 
 destroyed, and consequently requires very little 
 renewal by the functional activity of the animal 
 machine. Its metabolism destruction and renewal 
 is in every case infinitely less than is supposed in 
 the classical image of the vital vortex. It is the 
 merit of physiologists, and particularly of Pfliiger and 
 Chauveau, to have worked for nearly forty years 
 to establish this truth. They have proved it, at 
 least as far as the muscular tissue is concerned. 
 Protoplasm, properly so-called, is only destroyed 
 as the organs of a steam engine are destroyed its 
 tubes, its boiler, its furnace. And it matters little. 
 We know that such an engine uses much coal, and we 
 know very little of its machinery and its metallic 
 frame. And so it is with the cell, the living machine. 
 A very small portion of the food introduced will be 
 assimilated in the living substance. By far the 
 greater part of it is destined to be worked up by the 
 protoplasm and placed in reserve under the form of 
 glycogen, albumen, and fat, etc. i.e., compounds 
 which are not the really living substance, the hereditary 
 protoplasm, but the products of its industry, just as 
 they are or may be the products of the industry of 
 the chemist working in his laboratory. They will be 
 expended for the purpose of furnishing the necessary 
 energy to the vital functional activity, muscular
 
 NUTRITION. 231 
 
 contraction, secretion, heat, etc., just as coal is 
 expended to set the steam engine going. The proof 
 as far as the muscle is concerned does not stand 
 alone. There are other examples. In particular, 
 micrographic physiologists who have studied nervous 
 phenomena say that the anatomical elements of the 
 brain last indefinitely, and that they continue as they 
 are, without renewal from birth to death. The 
 permanence of the consciousness, be it said in 
 passing, is connected by them with the permanence 
 of the cerebral element (Marinesco). 
 
 Thus destruction is very restricted. There is only 
 a very slight disassimilation of the living matter, 
 properly so-called, in the course of the vital functional 
 activity. We may even go farther than this ex- 
 perimental fact. This is what Le Dantec has done 
 when he claims that there is even an assimilation, an 
 increase of the protoplasm. Strictly speaking, this 
 is possible, but there is no certain proof of it ; and in 
 any case we cannot agree with him when he affirms 
 that the increase is the direct result of the functional 
 activity and blends with it in one single, unique 
 operation. We must, on the contrary, agree with 
 Claude Bernard that it is only a consequence of it, 
 that it is produced in consequence of the existence of 
 a bond of correlation between organic destruction and 
 assimilating synthesis. 
 
 Why is there this bond ? That is easily under- 
 stood if we reflect that the assimilating synthesis, an 
 operation of endothermic, chemical complexity, natur- 
 ally requires an exothermic counterpart, the organic 
 destruction which will set free this necessary energy. 
 
 Formative Assimilation of Reserve^stuff. Forma' 
 ting Assimilation of Protoplasm. It follows that 
 
 16
 
 232 LIFE AND DEATH. 
 
 there are in nutritive assimilation itself two distinct 
 acts. The one consisting of the manufacture of 
 reserve-stuff is the more obvious but the less 
 specific ; the other, really essential, is assimilation 
 properly so-called, the reconstitution of the proto- 
 plasm. The former is indispensable to the pro- 
 duction of the most prominent acts of vitality 
 movement, secretion, production of heat. If it is 
 suspended, functional activity is arrested. We get 
 apparent death, or latent life. But if the real assimi- 
 lation is arrested, we have real deatJi. 
 
 According to this there would be a fundamental 
 distinction between real and apparent death. The 
 former would be characterized by an arrest of the 
 protoplasmic assimilation which is externally indicated 
 by no sign. On the other hand, apparent death 
 would be characterized by the arrest of the formation 
 and destruction of reserve-stuff. It would be ex- 
 ternally manifested by two signs : The suppression 
 of material exchanges with the medium (respiration, 
 alimentation) and the suppression of the functional 
 acts (production of movement, of heat, of electricity, 
 of glandular excretion). 
 
 Such would be the most expedient test for apparent 
 or real death. The question occurs in the case of 
 grains of corn in Egyptian tombs, and also of 
 hibernating animals and reviviscent beings, and, in 
 general, in the case of what has been called the state 
 of latent life. But from the practical point of view 
 it is extremely difficult to apply this test and to 
 decide if the phenomena which are arrested in the 
 grain at maturity, in Lceuwenhoek's tardigrada, 1 
 
 1 Bear-animalcules, Sloth-animalcules. An order of Arach- 
 nida. TR.
 
 NUTRITION. 233 
 
 and in the dried-up Anguillulidae 1 of Baker and 
 Spallanzani, in the encysted colpoda 2 that a drop of 
 warm water will revive, in the animals exposed by 
 E. Yung and Pictet to a cold of more than a 
 100 C. below zero, are due to the general arrest of 
 the two forms of assimilation, or to the arrest of the 
 manufacture and utilization of reserve-stuff alone, or 
 finally, to the arrest of protoplasmic assimilation 
 alone. The latter, which is already very restricted 
 in beings in a normal condition whose growth is 
 terminated, may fall to the lowest degree in the 
 being which, having no functional activity, is assimi- 
 lating nothing. So that, to cut the question short, 
 the experimenter who measures the value of the 
 exchanges between the being and the medium has 
 seldom to do more than decide between little and 
 nothing. Hence his perplexity. But if experiment 
 hesitates, theory affirms : it admits a priori that the 
 movement of protoplasmic assimilation, an essential 
 sign of vitality, is neither checked nor renewed, but 
 proceeds continuously. 
 
 Is Nutrition, tlie Assimilating Synthesis, inter- 
 rupted? Nevertheless, there are many reasons for 
 suspending all judgment as to this interpretation. 
 It is questioned by most biologists. According to 
 A. Gautier, the preserved grain of corn and the dried 
 up rotifera are not really alive ; they are like clocks 
 in working order, ready to tell the time, but awaiting 
 in absolute repose the first vibration which will set 
 them going. As for the grain, it is the air, heat, and 
 
 1 Minute thread worms, known as paste-eels and vinegar* 
 eels. TR. 
 
 2 Genus of Infusoria. ColpoiUa cucullus is found in infusions 
 of hay TR.
 
 234 LIFE AND DEATH. 
 
 moisture which supply the first impulse. In other 
 words, the organization proper to the manifestation of 
 life remains, but there is no life. The so-called 
 arrested life is not a life. 
 
 It must be said, however, that the majority of 
 physiologists refuse to accept this interpretation. 
 They believe in an attenuation of the nutritive 
 synthesis and not in its complete destruction. They 
 think that this total suppression would be contrary 
 to current ideas relative to the perpetuity of the 
 protoplasm and the limited duration of the living 
 element. The natural medium is variable, and even 
 the mineral cannot remain eternally fixed. Still less 
 is perennity a property of the living being. If 
 ordinary life is for each individual of limited duration, 
 the arrested life must also be of limited duration. 
 We cannot believe that after an indefinitely prolonged 
 sleep the grain of corn, or the paste-eel, or the 
 colpoda, emerging from their torpor can resume their 
 existence, like the Sleeping Beauty, at the point at 
 which it was interrupted, and thus pass with a bound, 
 as it were, through the centuries. 
 
 In fact the maintenance of the vitality of grains 
 of corn from the Egyptian tombs and their aptitude 
 to germinate after thousands of years are only fables 
 or the result of imposture. Maspero, in a letter 
 addressed to M. E. Griffon on the isth July 1901, 
 has clearly summed up the situation by saying that 
 the grains of corn bought from the fellahs almost 
 always germinate, but that this is never the case with 
 those that the experimenter himself takes from the 
 tombs. 
 
 To sum up, we must use the same language of 
 nutrition and of life, of their uninterrupted progress,
 
 NUTRITION. 235 
 
 of their continuity, of their permanence, of their 
 activity, and of their slackening. Living matter is 
 always growing, much or little, slowly or quickly, 
 in its reserve-stuff or in its protoplasm, for expenditure 
 or accumulation. This inevitability of growth defines 
 it, characterizes it, and sums up its activity. Develop- 
 ment and the evolution of growth are consequences or 
 aspects of nutrition.
 
 BOOK IV. 
 
 THE LIFE OF MATTER. 
 
 Summary: Chap. I. Universal life Opinions of philosophers 
 and poets Continuity between brute and living bodies 
 Origin of this principle. Chap. II. Origin of brute matter 
 in living matter. Chap. III. Organization and chemical 
 composition of brute and living bodies. Chap. IV. Evolu- 
 tion and transformation of brute and living bodies. 
 Chap. V. Possession of a specific form Living bodies and 
 crystals Cicatrization. Chap. VI. Nutrition in the living 
 body and in the crystal. Chap. VII. Generation in brute 
 and in living bodies Spontaneous generation. 
 
 Apparent Differences between Living and Brute 
 Bodies. The Two Kingdoms. It seems at first 
 impossible that there should be any essential 
 similarity between an inanimate object and a living 
 being. What resemblance can be discovered between 
 a stone, a lion, and an oak ? A comparison of the 
 inert and immovable pebble with the leaping animal, 
 and with the plant extending its foliage gives an 
 impression of vivid contrast. Between the organic 
 and the inorganic worlds there seems to be an abyss. 
 The first impressions we receive confirm this view ; 
 superficial investigation furnishes arguments for it. 
 There is thus aroused in the mind of the child, and 
 later in that of the man, a sharply marked distinction 
 between the natural objects of the mineral kingdom 
 on the one hand, and those of the two kingdoms of 
 living beings on the other. 
 
 236
 
 THE LIFE OF MATTER. 237 
 
 But a more Intimate knowledge daily tends to 
 throw doubt upon the rigour or the absolute character 
 of such a distinction. It shows that brute matter can 
 no longer be placed on one side and living beings on 
 the other. Scientists deliberately speak of a the life 
 of matter, 7 " which seems to the average man a con- 
 tradiction in terms. They discover in certain classes 
 of mineral bodies almost all the attributes of life. 
 They find in others fainter, but still recognizable 
 indications of an undeniable relationship. 
 
 We 'propose to pass in review these analogies and 
 rpgpiTflilaiinre as has already been done in a fairly 
 complete manner by Leo Errera, C EL Gnillanme, 
 C Bourdean, Ed. Griffon, and others. We will con- 
 sider the fine researches of Ranber, of Ostwald, 
 and of Tammann upon crystals and crystalline germs 
 researches which are merely a continuation of those 
 of Pasteur and of Gernez. These show that crystaH- 
 Hne bodies are endowed with the principal attributes 
 of living beings *>, a rigorously defined form ; an 
 aptitude for acquiring it, and for re-establishing it by 
 rrpaifing any mutilations that may be inflicted upon 
 it; nutritive growth at the expense of the mother 
 liquor which constitutes its culture medium ; and, 
 finally a still more incredible property all the 
 characteristics of reproduction by generation. Other 
 curious facts observed by skilful physicists W. 
 Roberts-Austen, W. Spring, Stead, Osmond, Guille- 
 min, Charpy, C. E. Guillaume show that the immu- 
 tability even of bodies supposed to be the most rigid 
 of all, such as glass, the metals, steel, and brass, is 
 apparent rather than real Beneath the surface of the 
 metal that seems to us inert there is a swarming 
 population of molecules, displacing each other, moving
 
 238 LIFE AND DEATH. 
 
 about, and arranging themselves so as to form definite 
 figures, and assuming forms adapted to the conditions 
 of the environment. Sometimes it is years before 
 they arrive at the state of ultimate and final equili- 
 brium which is that of eternal rest. 
 
 However, in order to understand these facts and 
 their interpretations, it is necessary to pass in review 
 the fundamental characteristics of living beings. It 
 will be shown that these very characteristics are found 
 in inanimate matter.
 
 CHAPTER L 
 
 UNIVERSAL LIFE, OPIXIOX5 OF PHILOSOPHERS 
 AXD POETS. 
 
 i. Primitire beliefe; the ideas of poets. | 2. Opinions of 
 from brute to Grieg bodies Hoe 
 
 by summation Ideas of philosopher as to sensibility and 
 in brate bodies The general principle of 
 
 i. PRIMITIVE BELIEFS. IDEAS OF THE POETS. 
 
 The teaching of science as to the analogies between 
 brute bodies and living bodies accords with the con- 
 ceptions of the philosophers and the fancies of the 
 poets. The ancients held that all bodies in nature 
 were the constituent parts of a universal organism, 
 the macrocosm, which they compared to the human 
 microcosm. They attributed to it a principle of 
 action, the psyche, analogous to the vital principle, 
 and this psyche directed phenomena; and also an 
 intelligent principle, the MOHS, analogous to the soul, 
 and the turns served for the comprehension of pheno- 
 mena. This universal life and this universal soul 
 played an important part in their metaphysical 
 systems. 
 
 239
 
 240 LIFE AND DEATH. 
 
 It was the same with the poets. Their tendency 
 has always been to attribute life to Nature, so as to 
 bring her into harmony with our thoughts and feel- 
 ings. They seek to discover the life or soul hidden 
 in the background of things. 
 
 " Hark to the voices. Nothing is silent. 
 
 Winds, waves, and flames, trees, reeds, and rocks 
 All live; all are instinct with soul." 
 
 After making proper allowance for emotional 
 exaggeration, ought we to consider these ideas as the 
 prophetic divination of a truth which science is only 
 just beginning to dimly perceive? By no means. As 
 Renan has said, this universal animism, instead of 
 being a product of refined reflection, is merely a 
 legacy from the most primitive of mental processes, 
 a residue of conceptions belonging to the childhood 
 of humanity. It recalls the time when men conceived 
 of external things only in terms of themselves; when 
 they pictured each object of nature as a living being. 
 Thus, they personified the sky, the earth, the sea, the 
 mountains, the rivers, the fountains, and the fields. 
 They likened to animate voices the murmur of the 
 forest : 
 
 ". . . The oak chides and the birch 
 Is whispering. . . . 
 And the beech murmurs. . . . 
 
 The willow's shiver, soft and faint, sounds like a word. 
 The pine-tree utters mysterious moans." 
 
 For primitive man, as for the poet of all times, 
 everything is alive, and every sound is due to a being 
 with feelings similar to our own. The sighing of the 
 breeze, the moan of the wave upon the shore, the
 
 UNIVERSAL LIFE. 241 
 
 babbling of the brook, the roaring of the sea, and the 
 pealing of the thunder are nothing less than sad, 
 joyous, or angry living voices. 
 
 These impressions were embodied in ancient 
 mythology, the graceful beauty of which does not 
 conceal its inadequacy. Then they passed into 
 philosophy and approached the realm of science. 
 Thales believed that all bodies in nature were 
 animate and living. Origen considered the stars as 
 actual beings. Even Kepler himself attributed to the 
 celestial bodies an internal principle of action, which, 
 it may be said in passing, is contrary to the law of 
 the inertia of matter, which has been wrongly ascribed 
 to him instead of to Galileo. The terrestrial globe 
 was, according to him, a huge animal, sensitive to 
 astral influences, frightened at the approach of the 
 other planets, and manifesting its terror by tempests, 
 hurricanes, and earthquakes. The wonderful flux and 
 reflux of the ocean was its breathing. The earth had 
 its blood, its perspiration, its excretions ; it also had 
 its foods, among which was the sea water which it 
 absorbs by numerous channels. It is only fair to add 
 that at the end of his life Kepler retracted these vague 
 dreams, ascribing them to the influence of J. C. 
 Scaliger. He explained that by the soul of the 
 celestial bodies he meant nothing more than their 
 motive force. 
 
 2. OPINION OF THE PHILOSOPHERS. 
 
 Transition from Brute to Living Bodies- The 
 lowering of the barrier between brute bodies and 
 living bodies began with those philosophers who
 
 242 t LIFE AND DEATH. 
 
 introduced into the world the great principles of 
 continuity and evolution. 
 
 The Principle of Continuity. First and foremost 
 we must mention Leibniz. According to the teaching 
 of that illustrious philosopher, as interpreted by M. 
 Fouillee, "there is no inorganic kingdom, only a great 
 organic kingdom, of which mineral, vegetable, and 
 animal forms are the various developments. . . . 
 Continuity exists everywhere throughout the world ; 
 everywhere is life and organization. Nothing is 
 dead ; life is universal." It follows that there is no 
 interruption or break in the succession of natural 
 phenomena; that everything is gradually developed; 
 and finally, that the origin of the organic being must 
 be sought in the inorganic. Life, properly so called, 
 has not, in fact, always existed on the surface of the 
 globe. It appeared at a certain geological epoch, in 
 a purely inorganic medium, by reason of favourable 
 conditions. The doctrine of continuity compels us, 
 however, to admit that it pre-existed on the globe 
 under some rudimentary form. 
 
 The modern philosophers who are imbued with 
 these principles, MM. Fouillee, L. Bourdeau, and A. 
 Sabatier, express themselves in similar language. 
 " Dead matter and living matter are not two abso- 
 lutely different entities, but represent two forms of 
 the same matter, differing only in degree, sometimes 
 but slightly." When it is only a matter of degree, it 
 cannot be held that these views are opposed. In- 
 equalities must not be interpreted as contrary attri- 
 butes, as when the untrained mind considers heat 
 and cold as objective states, qualitatively opposed 
 to each other. 
 
 Continuity by Transition. The argument which
 
 UNIVERSAL LIFE. 243 
 
 leads us to remove the barrier between the two king- 
 doms, and to consider minerals as endowed with a 
 sort of rudimentary life, is the same as that which 
 compels us to admit that there is no fundamental 
 difference between natural phenomena. There are 
 transitions between what lives and what does not; 
 between the animate being and the brute body. And 
 in the same way there are transitions between what 
 thinks and what does not think, between what is 
 thought and what is not thought, between the con- 
 scious and the unconscious. This idea of insensible 
 transition, of a continuous path between apparent 
 antitheses, at first arouses an insuperable opposition 
 in minds not prepared for it by a long comparison of 
 facts. It is slowly realized, and finally is accepted by 
 those who, in the world of things, follow die infinity 
 of gradations presented by natural phenomena. The 
 principle of continuity comes at last to constitute, as 
 one may say, a mental habit Thus the man of science 
 may be led, like the philosopher, to entertain the 
 idea of a rudimentary form of life animating matter. 
 He may, like the philosopher, be guided by this idea; 
 he may attribute a priori to brute matter all the really 
 essential qualities of living beings. But this must 
 be on the condition that, assuming these properties to 
 be common, he must afterwards demonstrate them by 
 means of observation and experiment He must show 
 that molecules and atom*, far from being inert and 
 dead masses, are in reality active elements, endowed 
 with a kind of inferior life, which is manifested by all 
 the transformations observed in brute matter, by 
 attractions and repulsions, by movements in response 
 to external stimuli, by variations of state and of 
 equilibrium; and finally, by the systematic methods
 
 244 LIFE AND DEATH. 
 
 according to which these elements group themselves, 
 conforming to those definite types of structure by 
 means of which they produce different species of 
 chemical compounds. 
 
 Continuity by Summation. The idea of summation 
 leads by another path to the same result. It is 
 another form of the principle of continuity. A sum 
 total of effects, obscure and indistinct in themselves, 
 produces a phenomenon appreciable, perceptible, and 
 distinct, apparently, but not really, heterogeneous in 
 its components. The manifestations of atomic or 
 molecular activity thus become manifestations of vital 
 activity. 
 
 This is another consequence of the teaching of 
 Leibniz. For, according to his philosophical theory, 
 individual consciousness, like individual life, is the 
 collective expression of a multitude of elementary 
 lives or consciousnesses. These elements are in- 
 appreciable because of their low degree, and the real 
 phenomenon is found in the sum, or rather the 
 integral, of all these insensible effects. The ele- 
 mentary consciousnesses are harmonized, unified, 
 integrated into a result that becomes manifest, just 
 as " the sounds of the waves, not one of which would 
 be heard if by itself, yet, when united together and 
 perceived at the same instant, become the resounding 
 voice of the ocean." 
 
 Ideas of the Philosophers as to Sensibility and Con- 
 sciousness in Brute Bodies. The philosophers have 
 gone still further in the way of analogies, and have 
 recognized in the play of the forces of brute matter, 
 particularly in the play of chemical forces, a mere 
 rudiment of the appetitions and tendencies that regu- 
 late, as they believe, the functional activity of living
 
 UNIVERSAL LIFE. 245 
 
 beings a trace, as it were, of their sensibility. To 
 them reactions of matter indicate the existence of a 
 kind of Jiedonic consciousness i.e., a consciousness 
 reduced simply to a distinction between comfort and 
 discomfort, a desire for good and repulsion from evil, 
 which they suppose to be the universal principle of all 
 activity. This was the view held by Empedocles in 
 antiquity; it was that of Diderot, of Cabanis, and, in 
 general, of the modern materialistic school, eager to 
 find, even in the lowest representatives of the 
 inorganic world, the first traces of the vitality and 
 intellectual life which blossom out at the top of the 
 scale in the living world. 
 
 Similar ideas are clearly seen in the early history of 
 all natural sciences. It was this same principle of 
 appetition, or of love and of repulsion or hate that, 
 under the names of affinity, selection, and incom- 
 patibility, was thought to direct the transformations of 
 bodies when chemistry first began ; when Boerhaave, 
 for example, compared chemical combinations to 
 voluntary and conscious alliances, in which the 
 respective elements, drawn together by sympathy, 
 contracted appropriate marriages. 
 
 General Principle of tlie Homogeneity of the Complex 
 and its Components. The assimilation of brute bodies 
 to living bodies, and of the inorganic kingdom to the 
 organic, was, in the mind of these philosophers, the 
 natural consequence of positing a priori the principles 
 of continuity and evolution. There is, however, a 
 principle underlying these principles. This principle 
 is not expressed explicitly by the philosophers; it is 
 not formulated in precise terms, but is more or less 
 unconsciously implied; it is everywhere applied. It, 
 however, may be clearly seen behind the apparatus of
 
 246 LIFE AND DEATH. 
 
 philosophical argument. It is the assertion that no 
 arrangement or combination of elements can put 
 forth any new activity essentially different from the 
 activities of the elements of which it is composed. 
 Man is living clay, say Diderot and Cabanis; and, 
 on the other hand, he is a thinking being. As it is 
 impossible to produce tliat wliicJi tJiinks from tliat wliicli 
 does not think, the clay must possess a rudiment of 
 thought. But is there not another alternative ? May 
 not the new phenomenon, thought, be the effect of 
 the arrangement of this clay? If we exclude this 
 alternative, we must then consider arrangement and 
 organization as incapable of producing in arranged 
 and organized matter a new property different from 
 that which it presented before such arrangement. 
 Living protoplasm, says another, is merely an 
 assemblage of brute elements; "these brute elements 
 must therefore possess a rudiment of life." This is 
 the same implied supposition which we have just 
 considered ; if life is not the basis of each element, it 
 cannot result from their simple assemblage. 
 
 Man and animals are combinations of atoms, says 
 M. le Dantec. It is more natural to admit that 
 human consciousness is the result of the elementary 
 consciousness of the constituent atoms than to con- 
 sider it as resulting from construction by means 
 of elements with no consciousness. " Life," says 
 Haeckel, "is universal; we could not conceive of its 
 existence in certain aggregates of matter if it did not 
 belong to their constituent elements." Here the 
 postulate is almost expressed. 
 
 The argument is always the same ; even the same 
 Words are used : the fundamental hypothesis is the 
 same j only it remains more or less unexpressed,
 
 UNIVERSAL LIFE. 247 
 
 more or less unperceived. It may be stated as 
 follows : Arrangement, assemblage, construction, and 
 aggregation are powerless to bring to light in the 
 complex anything new and essentially heterogeneous 
 to what already exists in the elements. Reciprocally, 
 grouping reveals in a complex n property and 
 character which is the gradual development of an 
 analogous property and character in the elements. 
 It is in this sense that there exists a collective soul in 
 crowds, the psychology of which has been discussed 
 by M. G. Le Bon. In the same way, many sociolo- 
 gists, adopting the views advanced by P. de Lilienfeld 
 in 1865, attribute to nations a formal individuality, 
 after the type of that possessed by each of their 
 constituent members. M. Izolet considers society 
 as an organism, which he calls a " hyperzoan. 
 Herbert Spencer has developed the comparison of 
 the collective organism with the individual organism, 
 insisting on their resemblances and differences. Th. 
 Ribot has dwelt, in particular, on the resemblances. 
 
 The postulate that we have clearly stated here is 
 accepted by many as an axiom. But it is not an 
 axiom. When we say that there is nothing in the 
 complex that cannot be found in the parts, we think 
 we are expressing a self-evident truth ; but we are, 
 in fact, merely stating an hypothesis. It is assumed 
 that arrangement, aggregation, and complicated and 
 skilful grouping of elements can produce nothing 
 really new in the order of phenomena. And this is 
 an assertion that requires verification in each par- 
 ticular case. 
 
 TJte Principle of Continuity, a Consequence of the 
 Preceding. Let us apply this principle to the beings 
 in nature. All beings in nature are, according to
 
 248 LIFE AND DEATH. 
 
 current ideas, arrangements, aggregates, or groupings 
 of the same universal matter, that is to say, of the 
 same simple chemical bodies. It results from the 
 preceding postulate that their activities can only differ 
 in degree and form, and not fundamentally. There 
 is no essential difference of nature between the 
 activities of various categories of beings, no hetero- 
 geneity, no discontinuity. We may pass from one to 
 another without coming to an hiatus or impassable 
 gulf. The law of continuity thus appears as a simple 
 consequence of the fundamental postulate. And so 
 it is with the law of evolution, for evolution is merely 
 continuity of action. 
 
 Such are the origins of the philosophical doctrine 
 which universalizes life and extends it to all bodies 
 in nature. 
 
 It may be remarked that this doctrine is not 
 confined to any particular school or sect. Leibniz 
 was by no means a materialist, and he endowed his 
 mundane elements, his monads, not only with a sort 
 of life, but even with a sort of soul. Father Bosco- 
 vitch, Jesuit as he was, and professor in the college of 
 Rome, did not deny to his indivisible points a kind of 
 inferior vitality. St. Thomas, too, the angelical 
 doctor, attributed, according to M. Gardair, to 
 inanimate substances a certain kind of activity, 
 inborn inclinations, and a real appetition towards 
 certain acts.
 
 CHAPTER II. 
 
 ORIGIN OF BRUTE MATTER IN LIVING MATTER. 
 
 Spontaneous generation: an episode in the history of the 
 globe Verification of the identity between brute and 
 living matter Slow identification Rapid identification 
 Contrary opinion Hypothesis of cosmozoa ; cosmic 
 panspermia Hypothesis of pyrozoa. 
 
 THERE should be two ways of testing the doctrine of 
 the essential identity of brute and living matter 
 one slow and more laborious, the other more rapid 
 and decisive. 
 
 Identification of tfie Two Matters, Brute and 
 Living. The laborious method, which we will be 
 obliged to follow, consists in the attentive examina- 
 tion of the various activities by which life is 
 manifested, and in finding more or less crude 
 equivalents for them in all brute beings, or in certain 
 of them. 
 
 Rapid Verification. Spontaneous Generation. The 
 rapid and decisive method, which, unhappily, is 
 beyond our resources, would consist in showing un- 
 questionable, clearly marked life, the superior life, 
 arising from the kind of inferior life that is attributed 
 to matter in general. It would be necessary com- 
 pletely to construct in all its parts, by a suitable 
 combination of inorganic materials, a single living 
 being, even the humblest plant or the most rudi- 
 249
 
 250 LIFE AND DEATH. 
 
 mentary animal. This would indeed be an irrefutable 
 proof that the germs of all vital activity are contained 
 in the molecular activity of brute bodies, and that 
 there is nothing essential to the latter that is not 
 found in the former. 
 
 .Unhappily this demonstration cannot be given. 
 Science furnishes no example of it, and we are forced 
 to have recourse to the slow method. 
 
 The question here involved is that of spontaneous 
 generation. It is well known that the ancients 
 believed in spontaneous generation, even for animals 
 high in the scale of organization. According to 
 Van Helmont, mice could be born by some incom- 
 prehensible fermentation in dirty linen mixed with 
 wheat. Diodorus speaks of animal forms which were 
 seen to emerge, partly developed, from the mud of 
 the Nile. Aristotle believed in the spontaneous birth 
 of certain fishes. This belief, though rejected as to 
 the higher forms, was for a long time held with 
 regard to the lower forms of animals, and to insects 
 such as the bees which the shepherd of Virgil saw 
 coming out from the flanks of the dead bullock 
 flies engendered in putrefying meat, fruit worms and 
 intestinal worms ; finally, with regard to infusoria 
 and the most rudimentary vegetables. The hypo- 
 thesis of the spontaneous generation of the living 
 being at the expense of the materials of the ambient 
 medium has been successively driven from one 
 classificatory group to another. The history of the 
 sciences of observation is also a history of the con- 
 futation of this theory. Pasteur gave it the finishing 
 stroke, when he showed that the simplest micro- 
 organisms obeyed the general law which declares 
 that the living being is formed only by filiation that
 
 ORIGIN OF BRUTE MATTER. 251 
 
 is to say, by the intervention of a pre-existing living 
 organism. 
 
 Spontaneous Generation an Episode in tfie History 
 of the Globe. Though we have been unable to effect 
 spontaneous generation up to the present, it has been 
 referred by Haeckel to a more or less distant past, to 
 the time when the cooling of the globe, the solidifica- 
 tion of its crust, and the condensation of aqueous 
 vapour upon its surface created conditions compatible 
 with the existence of li\yng beings similar to those 
 with which we are acquainted. Lord Kelvin has 
 fixed these geological events as occurring from twenty 
 to forty million years ago. Then circumstances 
 became propitious for the appearance of the first 
 organisms, whence were successively derived those 
 which now people the earth and the waters. 
 
 Circumstances favourable to the appearance of the 
 first beings apparently occurred only in a far distant 
 past ; but most physiologists admit that if we knew 
 exactly these circumstances, and could reproduce 
 them, we might also expect to produce their effect 
 namely, the creation of a living being, formed in all 
 its parts, developed from the inorganic kingdom. 
 To all those who held this view the impotence of 
 experiment at the present time is purely temporary. 
 It is comparable to that of primitive men before the 
 time of Prometheus ; they, not knowing how to 
 produce fire, could only get it by transmitting it 
 from one to another. It is due to the inadequacy 
 of our knowledge and the weakness of our means ; it 
 does not contradict the possibility of the fact 
 
 Contrary Opinion. Life did not Originate on our 
 Globe. But all biologists do not share this opinion. 
 Some, and not the least eminent, hold it to be an
 
 252 LIFE AND DEATH. 
 
 established fact that it is impossible for life to arise 
 from a concurrence of inorganic materials and forces. 
 This was the opinion of Ferdinand Cohn, the great 
 botanist ; of H. Richter, the Saxon physician, and of 
 W. Preyer, a physiologist well known from his 
 remarkable researches in biological chemistry. 
 According to these scientists, life on the surface of 
 the globe cannot have appeared as a result of the 
 reactions of brute matter and the forces that continue 
 to control it. 
 
 According to F. Cohn and II. Richter, life had no 
 beginning on our planet. It was transported to the 
 earth from another world, from the cosmic medium, 
 under the form of cosmic germs, or cosmozoa, more 
 or less comparable to the living cells with which we 
 are acquainted. They may have made the journey 
 either enclosed in meteorites, or floating in space in 
 the form of cosmic dust. The theory in question 
 has been presented in two forms : The Hypothesis of 
 Meteoric Cosmozoa, by a French writer, the Count 
 de Salles-Guyon ; and that of cosmic panspennia 
 brought forward in 1865 and 1872 by F. Cohn and 
 H. Richter. 
 
 Hypothesis of the Cosinozoa. The hypothesis of 
 the cosmozoa, living particles, protoplasmic germs 
 emanating from other worlds and reaching the earth 
 by means of aerolites, is not so destitute of probability 
 as one might at first suppose. Lord Kelvin and 
 Helmholtz gave it the support of their high authority. 
 Spectrum analysis shows in cometary nebulae the 
 four or five lines characteristic of hydro-carbons. 
 Cosmic matter, therefore, contains compounds of 
 carbon, substances that are especially typical of 
 organic chemistry. Besides, carbon and a sort of
 
 ORIGIN OF BRUTE MATTER. 253 
 
 humus have been found in several meteorites, To 
 the objection that these aerolites are heated while 
 passing through our atmosphere, Helmholtz replies 
 that this elevation of temperature may be quite 
 superficial and may allow micro-organisms to subsist 
 in their interior. But other objections retain their 
 force : First, that of M. Verwom, who considers the 
 hypothesis of cosmic germs as inconsistent with the 
 laws of evolution ; and that of L, Errera, who denies 
 that the conditions necessary for life exist in inter- 
 planetary bodies. 
 
 Hypothesis of Cosmic Panspcrmia, Du Bois- 
 Reymond has given the name of cosmic paxspcrmia 
 to a theory very similar to the preceding, formulated 
 by F. Cohn in 1872. The first living germs arrived 
 en our globe mingled with the cosmic dust that 
 floats in space and falls slowly to the surface of the 
 earth. li Errera observes that if they escape by 
 this gentle fall the dangerous heating of meteorites, 
 they still remain exposed to the action of the photic 
 rays, which is generally destructive to germs. 
 
 Hypothesis of Pjrosoa, W. Preyer declined to 
 accept this cosmic transmigration of the simplest 
 living beings, nor would he allow the intervention of 
 other worlds into the history of our own. Life, 
 according to him, must have existed from all time, 
 even when the globe was an incandescent mass. 
 But it was not the same life as at present. Vitality 
 must have undergone many profound changes in the 
 course of ages. The pyrosoa^ the first living beings, 
 vulcanians, were very different from the beings of 
 the present day that are destroyed by a slight 
 elevation of temperature. No doubt this theory of 
 pyrozoa, proposed by W. Preyer in 1872, seems
 
 254 LIFE AND DEATH. 
 
 quite chimerical, and akin to Kepler's dreamy visions. 
 But in a certain way it accords with contemporary 
 ideas concerning the life of matter. It is related to 
 them by the evolution which it implies in the materials 
 of the terrestrial globe. 
 
 According to Preyer, primitive life existed in fire. 
 Being igneous masses in fusion, the pyrozoa lived 
 after their own manner; their vitality, slowly modified, 
 assumed the form which it presents to-day. Yet, in 
 this profound transformation their number has not 
 varied, and the total quantity of life in the universe 
 has remained unchanged. 
 
 Here we recognize the ideas of 'Buffon. These 
 cosmozoa, these pyrozoa, have a singular resemblance 
 to the organic molecules of "live matter" of the 
 illustrious naturalist distributed everywhere, in- 
 destructible, and forming living structures by their 
 concentration. 
 
 But we must leave these scientific or philosophical 
 theories, and come to arguments based upon facts. 
 
 It is in a spirit quite different from that of the 
 poets, the metaphysicians, and the more or less 
 philosophical scientists that the science of our days 
 looks at the more or less obscure vitality of inanimate 
 bodies. It claims that we may recognize in them, 
 in a more or less rudimentary state, the action 
 of the factors which intervene in the case of living 
 beings, the manifestation of the same fundamental 
 properties.
 
 CHAPTER III. 
 
 ORGANIZATION AND CHEMICAL COMPOSITION OF 
 LIVING AND BRUTE MATTER. 
 
 Laws of the organization and of the chemical composition of 
 living beings Relative value of these lavs; vital pheno- 
 mena in crashed protoplasm Vital phenomena in brute 
 bodies, 
 
 Enumeration of ike Principal Characters of Living 
 Beings. The programme which we have just sketched 
 compels us to look in the brute being for the pro- 
 perties of living beings. What, then, are, in fact, the 
 characteristics of an authentic, complete, living being ? 
 What are its fundamental properties? We have 
 enumerated them above as follows : A certain 
 chemical composition, which is that of living matter : 
 a structure or organization ; a specific form ; an 
 evolution which has a duration, that of life, and an 
 end, death ; a property * of growth or nutrition ; a 
 property of reproduction. Which of these characters 
 counts for most in the definition of life ? Are they 
 all equally necessary ? If some of them were wanting, 
 would that justify the transference of a being, who 
 might possess the rest, from the animate world to 
 that of minerals ? This is precisely the question that 
 is under consideration. 
 
 Organization and Chemical Composition of Living 
 Beings. All that we know concerning the constitution 
 255
 
 256 LIFE AND DEATH. 
 
 of living matter and its organization is summed up in 
 the laws of the cliemical unity and the morphological 
 unity of living beings (v. Book III.). These laws seem 
 to be a legitimate generalization from all the facts 
 observed. The first states that the phenomena of 
 life are manifested only in and through living matter, 
 protoplasm i.e., in and through a substance which 
 has a certain chemical and physical composition. 
 Chemically it is a proteid complexus with a hexonic 
 nucleus. Physically it shows a frothy structure 
 analogous to that resulting from the mixture of two 
 granular, immiscible liquids, of different viscosities. 
 The second law states that the phenomena of life 
 can only be maintained in a protoplasm which has 
 the organization of the complete cell, with its cellular 
 body and nucleus. 
 
 Relative Value of these Laws. Exceptions. What 
 is the signification of these laws of the chemical 
 composition and organization of living beings? 
 Evidently that life in all its plenitude can only exist 
 and be perpetuated under their protection. If these 
 laws were absolute, if it were true that no life were 
 possible but in and through albuminous protoplasm, 
 but in and through the cell, the problem of " the life 
 of matter" would be decided in the negative. 
 
 May it not happen, however, that fragmentary and 
 incomplete vital manifestations, progressive traces 
 of a true life, may occur under different conditions; 
 for example, in matter which is not protoplasm, and 
 in a body which has a structure differing from that 
 of a cell that is to say, in a being which would be 
 neither animal nor plant? We must seek the answer 
 to this question by an appeal to experiment. 
 
 Without leaving the animal and vegetable king-
 
 ORGANIZATION AND CHEMICAL COMPOSITION. 257 
 
 doms i.e., real living beings we already see less 
 rigour in the laws governing chemical constitution 
 and cellular organization. 
 
 Experiments in merotomy i.e., in amputation 
 carried out on the nervous element by Waller, on 
 infusoria by Brandt, Gruber, Balbiani, Xussbaum, 
 and Verworn, show us the necessity of the presence 
 of the cellular body and the nucleus i.e., of the in- 
 tegrity of the cell. But they also teach us that when 
 that integrity no longer exists death does not imme- 
 diately follow. A part of the vital functions continues 
 to be performed in denucleated protoplasm, in a cell 
 which is mutilated and incomplete. 
 
 Vital Phenomena in Crushed Protoplasm. It is 
 true also that grinding and crushing suppress the 
 greater part of the functions of the cell. But tests 
 with pulps of various organs and with those of certain 
 yeasts also show that protoplasm, even though ground 
 and disorganized, cannot be considered as inert, and 
 that it still exhibits many of its characteristic pheno- 
 mena ; for example, the production of diastases, the 
 specific agents of vital chemistry. Finally, while we 
 do not know enough about the actions of which the 
 secondary elements of protoplasm its granulations, 
 its filaments are capable, which this or that method 
 of destruction may bring to light, at least we kno\v 
 that actions of this kind exist. 
 
 To sum up, we are far from being able to deny that 
 rudimentary, isolated vital acts may be produced by 
 the various bodies that result from the dismember- 
 ment of protoplasm. The integrity of the cellular 
 organization, even the integrity of protoplasm itself, 
 are therefore not indispensable for these partial 
 manifestations of vitality.
 
 258 LIFE AND DEATH. 
 
 Besides, biologists admit that there exist with- 
 in the protoplasm aliquot parts, elements of an 
 inferior order, which possess special activities. 
 These secondary elements must have the principle 
 of their activity within themselves. Such are the 
 biophors to which Weismann attributes the vital 
 functions of the cell, nutrition, growth, and multipli- 
 cation. If there are biophors within the cell, we 
 may imagine them outside the cell, and since they 
 carry within themselves the principle of their activity 
 they may exercise it in an independent manner. 
 Unhappily the biophors, and other constituent ele- 
 ments of that kind, are purely hypothetical. They 
 are like Darwin's gemmules, Altmann's bioblasts, and 
 the pangens of De Vries. They have no relation to 
 facts of observation and to real existence. 
 
 Vital Phenomena in Brute Bodies. There is no 
 doubt that certain phenomena of vitality may occur 
 outside of the cellular atmosphere. And carrying 
 this further, we may admit that they may be pro- 
 duced in certain slightly organized bodies (crushed 
 cells), and then in certain unorganized bodies in 
 certain brute beings. In every case it is certain that 
 effects are produced at any rate similar to those which 
 are characteristic of living matter. It is for observation 
 and experiment to decide as to the degree of similarity, 
 and their verdict is that the similarity is complete. 
 The crystals and the crystalline germs studied by 
 Ostwald and Tammann are the seat of phenomena 
 which are quite comparable to those of vitality.
 
 CHAPTER IV. 
 
 EVOLUTION AND MUTABILITY OF LIVING MATTER 
 AND BRUTE MATTER. 
 
 Supposed immobility of brute bodies Mobility and mutability 
 of the sidereal world. r. The movement of particles and 
 molecules in brute bodies The internal movements of 
 brute bodies Kinetic conception of molecular motion 
 Reality of the motion of particles Comparison of the 
 activity of particles with vital activity. 2. Brownian 
 movement Its existence Its character Its independence 
 of the nature of the bodies and of the nature of the environ- 
 ment Its indefinite duration Its independence of external 
 conditions The Brownian movement must be the first 
 stage of molecular motion. 3. Motion of panicles 
 Migration of material panicles Migration under the 
 action of weight ; of diffusion; of electrolysis; of mechanical 
 pressure. 4. Internal activity of alloys Their structure 
 Changes produced by deforming agencies Slow return to 
 equilibrium Residual effect Effect of annealing; effect 
 of stretching Nickel steel Colour photography Con- 
 clusion Relations of the environment to the living or brute 
 
 ONE of the most remarkable characteristics of a living 
 being is its evolution. It undergoes a continuous 
 change. It starts from something very small; it 
 assumes a configuration and grows ; in most cases 
 it declines and disappears, having followed a course 
 which may be predicted a sort of ideal trajectory. 
 
 Supposed Immobility of Brute Bodies. It may be 
 asked whether this evolution, this directed mobility, 
 259
 
 260 LIFE AND DEATH. 
 
 is so exclusively a feature of the living being as it 
 appears, and if many brute bodies do not present 
 something analogous to it. We may answer in no 
 uncertain tones. 
 
 Bichat was wrong when he contrasted in this 
 respect brute bodies with living bodies. Vital 
 properties, he said, are temporary; it is their nature 
 to be exhausted ; in time they are used up in the 
 same body. Physical properties, on the contrary, are 
 eternal. Brute bodies have neither a beginning nor 
 an inevitable end, neither age, nor evolution; they 
 remain as immutable as death, of which they are the 
 image. 
 
 Mobility and Mutability of the Sidereal World. 
 This is not true, in the first place, of the sidereal 
 bodies. The ancients held the sidereal world to be 
 immutable and incorruptible. The doctrine of the 
 incorruptibility of the heavens prevailed up to the 
 seventeenth century. The observers who at that 
 epoch directed towards the heavens the first telescope, 
 which Galileo had just invented, were struck with 
 astonishment at discovering a change in that celestial 
 firmament which they had hitherto believed incor- 
 ruptible, and at perceiving a new star that appeared 
 in the constellation Ophiuchus. Such changes no 
 longer surprise us. The cosmogonic system of 
 Laplace has become familiar to all cultivated minds, 
 and every one is accustomed to the idea of the con- 
 tinual mobility and evolution of the celestial world. 
 " The stars have not always existed," writes M. Faye ; 
 " they have had a period of formation ; they will 
 likewise have a period of decline, followed by final 
 extinction." 
 
 Thus all the bodies of inanimate nature are not
 
 EVOLtmOSC AXD MUTABILITY OF MATTER. 261 
 
 eternal and immutable; the celestial bodies are 
 eminently susceptible of evolution, slow indeed with 
 that we observe on the surface of our globe; but this 
 disproportion, corresponding to the immensity of 
 time and of cosmic spaces as compared with terres- 
 trial measurements, should not mislead us as to the 
 fundamental analogy of the phenomena. 
 
 I i. THE MOVEMEXT OF PARTICLES AXD MOLE- 
 CULES ra BRCTE BODIES. 
 
 It is not only in celestial spaces that we must 
 search for that mobility of brute matter which imitates 
 the mobility of living matter. In order to find it we 
 have only to look about us, or to inquire from 
 physicists and chemists. 
 
 As far as geologists are concerned, 3*L le Dantec 
 tells us somewhere of one who divided minerals into 
 living rocks rocks capable of change of structure, of 
 evolution under the influence of atmospheric causes ; 
 and dead rocks rocks which, like clay, have found at 
 the end of all their changes a final state of repose. 
 Jerome Cardan, a celebrated scientist of the sixteenth 
 century, at once mathffniti*~ian > naturalist, and 
 physician, declared not only that stones live, but 
 that they suffer from disease, grow old, and die. 
 The jewellers of the present day use similar language 
 of certain precious stones; the torquoise, for example. 
 
 The alchemists carried these ideas to an extreme. 
 It is not necessary here to recall the past, to evoke 
 the hermetic beliefs and the dreams of the alchemists, 
 who held that the different lands of matter lived, 
 developed, and were transmuted into each other.
 
 262 LIFE AND DEATH. 
 
 I refer to precise and recent data, established by 
 the most expert investigators, and related by one of 
 them, Charles Edward Guillaume, some years ago, 
 before the Societe lielvttique des Sciences naturcllcs. 
 These data show that determinate forms of matter 
 may live and die, in the sense that they may be 
 slowly and continuously modified, always in the same 
 direction, until they have attained an ultimate and 
 definitive state of eternal repose. 
 
 The Internal Movements of Bodies. Swift's reply to 
 an idle fellow who spoke slightingly of work is well 
 known. " In England," said the author of Gulliver's 
 Travels, " men work, women work, horses work, 
 oxen work, water works, fire works, and beer works ; 
 it is only the pig who does nothing at all; he must, 
 therefore, be the only gentleman in England." We 
 know very well that English gentlemen also work. 
 Indeed, everybody and everything works. And the 
 great wit was nearer right than he supposed in com- 
 paring men and things in this respect. Everything 
 is at work; everything in nature strives and toils, at 
 every stage, in every degree. Immobility and repose 
 in the case of natural things are usually deceptive; 
 the seeming quietude of matter is caused by our 
 inability to appreciate its internal movements. Be- 
 cause of their minuteness we do not perceive the 
 swarming particles that compose it, and which, under 
 the impassible surface of the bodies, oscillate, displace 
 each other, move to and fro, and group themselves 
 into forms and positions adapted to the conditions 
 of the environment. In comparison with these 
 microscopic elements we are like Swift's giant among 
 the Lilliputians; and this is far from being a suffi- 
 ciently forcible comparison.
 
 EVOLUTION AND MUTABILITY OF MATTER. 263 
 
 Kinetic Conception of Molecular Motion. The idea 
 of this peculiar form of motion is by no means new to 
 us. We were familiarized with it in scientific theories 
 during our school days. The atomic theory teaches 
 us that matter behaves, from a chemical point of 
 view, as if it were divided into molecules and atoms. 
 The kinetic theory explains the constitution of gases 
 and the effects of heat by supposing that these 
 particles are endowed with movements of rotation 
 and displacement The wave theory explains photic 
 phenomena by supposing peculiar vibratory move- 
 ments in a special medium the ether. But these 
 are merely hypotheses which are not at all necessary; 
 they are the images of things, not the things them- 
 selves, 
 
 Reality of tJi Motion of Particles. Here there is 
 no question of hypotheses. This internal agitation, 
 this interior labour, this incessant activity of matter 
 are positive facts, an objective reality. It is true that 
 when the chemical or mechanical equilibrium of 
 bodies is disturbed it is only" restored more or less 
 slowly. Sometimes days and years are required 
 before it is regained. Scarcely do they attain this 
 relative repose when they are again disturbed, for the 
 environment itself is not fixed; it experiences varia- 
 tions which react in their turn upon the body under 
 consideration ; and it is only at the end of these 
 variations, at the end of their respective periods, that 
 they will attain together, in a universal uniformity, an 
 eternal repose. 
 
 We shall see that metallic alloys undergo con- 
 tinual physical and chemical changes. They are 
 always seeking a more or less elusive equilibrium. 
 Physicists in modern times have given their attention 
 
 18
 
 264 LIFE AND DEATH. 
 
 to this internal activity of material bodies, to the 
 pursuit of stability. Wiedemann, Warburg, Tomlin- 
 son, MM. Duguet, Brillouin, Duhem, and Bouasse 
 have revived the old experimental researches of 
 Coulomb and Wertheim on the elasticity of bodies, 
 the effects of pressures and thrusts, the hammering, 
 tempering, and annealing of metals. 
 
 The internal activity manifested under these cir- 
 cumstances presents quite remarkable characteristics 
 which cannot but be compared to the analogous 
 phenomena presented by living bodies. Thus have 
 arisen even in physics, a figurative terminology, and 
 metaphorical expressions borrowed from biology. 
 
 Comparison of the Activity of Particles with Vital 
 Activity. Since Lord Kelvin first spoke of the fatigue 
 of metals, or the fatigue of elasticity, Bose has 
 shown in these same bodies the fatigue of electrical 
 contact. The term accommodation has been employed 
 in the study of torsion, and according to Tomlinson 
 for the very phenomena which are the inverse of 
 those of fatigue. The phenomena presented by glass 
 when acted on by an external force which slowly 
 bends it, have been called facts of adaptation. The 
 manner in which a bar of steel resists wire-drawing 
 has been compared to defensive processes against 
 threatened rupture. And M. C. E. Guillaume speaks 
 somewhere of " the heroic resistance of the bar of 
 nickel-steel." The term "defence" has also been 
 applied to the behaviour of chloride or iodide of 
 silver when exposed to light. 
 
 There has been no hesitation in using the term 
 " memory " concurrently with that of hysteresis to 
 designate the behaviour of bodies acted on by 
 magnetism or by certain mechanical forces. It is
 
 EVOLUTION AND MUTABILITY OF MATTER. 265 
 
 true that M. H. Bouasse protests in the name of the 
 physico-mathematicians against the employment of 
 these figurative expressions. But has he not himself 
 written " a twisted wire is a wound-up watch," and 
 elsewhere, " the properties of bodies depend at every 
 moment upon all anterior modifications " ? Does not 
 this imply that they retain in some manner the 
 impression of their past evolution ? Powerful de- 
 formative agencies leave a trace of their action ; they 
 modify the body's condition of molecular aggregation, 
 and some physicists go so far as to say that they even 
 modify its chemical constitution. With the exception 
 of M. Duhem, the disciples of the mechanical school 
 who have studied elasticity admit that the effect of an 
 external force upon a body depends upon the forces 
 which have been previously acting on it, and not 
 merely upon those which are acting on it at the 
 present moment. Its present state cannot be antici- 
 pated, it is the recapitulation of preceding states. 
 The effect of a torsional force upon a new wire will 
 be different from that of the same force upon a wire 
 previously subjected to torsions and detorsions. It 
 was with reference to actions of this kind that 
 Boltzmann, in 1876, declared that "a wire that has 
 been twisted or drawn out remembers for a certain 
 time the deformations which it has undergone." 
 This memory is obliterated and disappears after a 
 certain definite period. Here then, in a problem of 
 static equilibrium, we find introduced an unexpected 
 factor time. 
 
 To sum up, it is the physicists themselves who 
 have indicated the correspondence between the con- 
 dition of existence in many brute bodies and that in 
 many living bodies. It cannot be expected that
 
 266 LIFE AND DEATH. 
 
 these analogies will in any way serve as explanations. 
 We should rather seek to derive the vital from the 
 physical phenomenon. This is the sole ambition of 
 the physiologist. To derive the physical from the 
 vital phenomenon would be unreasonable. We do 
 not attempt to do this here. It is nevertheless true 
 that analogies are of service, were it only to shake the 
 support which, from the time of Aristotle, has been 
 accorded to the division of the bodies of nature into 
 psuchia and apsucliia i.e., into living and brute 
 bodies. 
 
 2. THE BROWNIAN MOVEMENT. 
 
 The Existence of the Brownian Movement. The 
 simplest way of judging of the working activity of 
 matter is to observe it when the liberty of the 
 particles is not interfered with by the action of the 
 neighbouring particles. We approximate to this 
 condition when we watch, through the microscope, 
 grains of dust suspended in a liquid, or globules of 
 oil suspended in water. Now what we see is well 
 known to all microscopists. If the granulations are 
 sufficiently small, they seem to be never at rest. 
 They are animated by a kind of incessant tremor ; 
 we see the phenomena called the " Brownian move- 
 ment." This movement has struck all observers since 
 the invention of the magnifying glass or simple 
 microscope. But the English botanist, Brown, in 
 1827, made it the object of special research and gave 
 it his name. The exact explanation of it remained 
 for a long time obscure. It was given in 1894 by 
 M. Gouy, the learned physicist of the Faculty of 
 Lyons.
 
 EVOLUTION AND MUTABILITY OF MATTER. 267 
 
 The observer who for the first time looks through 
 the microscope at a drop of water from the river, from 
 the sea, or from any ordinary source that is to say, 
 water not specially purified is struck with surprise 
 and admiration at the motion revealed to him. 
 Infusoria, microscopic articulata, and various micro- 
 organisms people the microscopic field, and animate 
 it by their movements ; but at the same time all sorts 
 of particles are also agitated, particles which cannot 
 be considered as living beings, and which are, in fact, 
 nothing but organic detritus, mineral dust, and debris 
 of every description. Very often the singular move- 
 ments of these granulations, which simulate up to a 
 certain point those of living beings, have perplexed 
 the observer or led him to erroneous conclusions, and 
 the bodies have been taken for animalcules or for 
 bacteria, 
 
 Cliaracters of this Movement. But it is as a rule 
 quite easy to avoid this confusion. The Brownian 
 movement is a kind of oscillation, a stationary, 
 dancing to-and-fro movement It is a Saint Vitus's 
 dance on one and the same spot, and is thus dis- 
 tinguished from the movements of displacement 
 customary with animate beings. Each particle has 
 its own special dance. Each one acts on its own 
 account, independently of its neighbour. There is, 
 however, in the execution of these individual oscilla- 
 tions a kind of common and regular character which 
 arises from the fact that their amplitudes differ 
 little from each other. The largest particles are 
 the slowest ; when above four thousandths of a 
 millimetre in diameter, they almost cease to be 
 mobile The smallest are the most active. When so 
 small as to be barely visible in the microscope, the
 
 268 LIFE AND DEATH. 
 
 movement is extremely rapid, and can only occasion- 
 ally be perceived. It is probable that it would be 
 still more accelerated in smaller objects; but the latter 
 will always escape our observation. 
 
 Its Independence of the Nature of the Bodies and of the 
 Environment, M. Gouy remarked that the move- 
 ment depends neither on the nature nor on the form 
 of the particles. Even the nature of the liquid has 
 but little effect. Its degree of viscosity alone comes 
 into play. The movements are, indeed, more lively 
 in alcohol or ether, which are very mobile liquids ; 
 they are slow in sulphuric acid and in glycerine. In 
 water, a grain one two-thousandth of a millimetre in 
 diameter traverses, in a second, ten or twelve times its 
 own length. 
 
 The fact that the Brownian movement is seen in 
 liquors which have been boiled, in acids and in 
 concentrated alkalies, in toxic solutions of all degrees 
 of temperature, shows conclusively that the pheno- 
 menon has no vital significance ; that it is in no way 
 connected with vital activity so called. 
 
 Its Indefinite Duration. The most remarkable char- 
 acter of this phenomenon is its permanence, its 
 indefinite duration. The movement never ceases, 
 the particles never attain repose and equilibrium. 
 Granitic rocks contain quartz crystals which, at the 
 moment of their formation, include within a closed 
 cavity a drop of water containing a bubble of gas. 
 These bubbles, contemporary with the Plutonian age 
 of the globe, have never since their formation ceased 
 to manifest the Brownian movement. 
 
 Its Independence of External Conditions. What is 
 the cause of this eternal oscillation ? Is it a tremor 
 of the earth ? No ! M. Gouy saw the Brownian
 
 EVOLCTTOH AXD MUTABILITY OF MATTER. 269 
 
 movement far away from cities; where the mercurial 
 mirror of a seismoscope showed no subterranean 
 vibration. It does not increase when the violations 
 occur and become quite appreciable. Neither is it 
 changed by variation in light, magnetism, or electric 
 influences; in a word, by any external occurrences. 
 The result of observation is to place before us the 
 paradox of a phenomenon which is kept up and 
 indefinitely perpetuated in the interior of a body 
 without known external cause. 
 
 TJu Srvsnriam Mmxm&U must be the first Stage of 
 Molecular Motion, When we take in our hands a 
 sheet of quartz containing a gaseous inclusion, we 
 seem to be holding a perfectly inert object. When 
 we have placed it upon the stage of the microscope, 
 and have seen the agitation of the bubble, we are 
 convinced that this seeming inertia is merely an 
 illusion. 
 
 Repose exists only because of our limited vision. 
 We see the objects as we see from alar a crowd of 
 people. We perceive them only as a whole, without 
 being able to discern the individuals or their move- 
 ments. A visible object is, in the same way, a mass 
 of particles. It is a molecular crowd. It gives us 
 the impression of an indivisible mass, of a block in 
 repose. 
 
 But as soon as the lens brings us near to this 
 crowd, as soon as the microscope enlarges for us the 
 minute elements of the brute body, then they appear 
 to us, and we perceive the continual agitation of those 
 elements which are less than four thousandths of a 
 millimetre in diameter. The smaller the particles 
 under consideration, the more lively are their move- 
 ments. From this we infer that if we could perceive
 
 270 LIFE AND DEATH. 
 
 molecules, whose probable dimensions are about one 
 thousand times less, their probable velocity would be, 
 as required by the kinetic theory, some hundreds of 
 metres per second. In the case of objects we can 
 only just see, the Brownian velocity is only a few 
 thousandths of a millimetre per second. No doubt, 
 concludes M. Gouy, the particles that show this 
 velocity are really enormous when compared with 
 true molecules. From this point of view the 
 Brownian movement is but the first degree, and a 
 magnified picture of the molecular vibrations assumed 
 in the kinetic theory. 
 
 3. THE INTERNAL ACTIVITY OF BODIES. 
 
 Migration of Material Particles. In the Brownian 
 movement we take into account only very small, 
 isolated masses, small free fragments i.e., material 
 particles which are not hampered by their relations to 
 neighbouring particles. Any one but a physicist 
 might believe that in true solids endowed with 
 cohesion and tenacity, in which the molecules were 
 bound one to the other, in which form and volume 
 are fixed, there could be no longer movements or 
 changes. This is a mistake. Physics teaches us the 
 contrary, and, in late years especially, has furnished 
 us characteristic examples. There are real migrations 
 of material particles throughout solid bodies migra- 
 tions of considerable extent. They are accomplished 
 through the agency of diverse forces acting externally 
 pressures, thrusts, torsions; sometimes under the 
 action of light, sometimes under the action of elec- 
 tricity, sometimes under the influence of forces of
 
 EVOLUTION AND MUTABILITY OF MATTER- 271 
 
 diffusion. The microscopic observation of alloys by 
 H. and A. Lechatelier, J. Hopkinson, Osmond, Charpy, 
 J. R. Benoit; researches into their physical and 
 chemical properties by Calvert, Matthiessen, Riche, 
 Roberts Austen, Lodge, Laurie, and C E. Guillaume ; 
 experiments on the electrolysis of glass, and the 
 curious results of Bose upon electrical contact of 
 metals, show in a striking manner the chemical and 
 kinetic evolutions which occur in the interior of 
 bodies. 
 
 Migration under tJu Action of Wright. An ex- 
 periment by Obermeyer, dating from 1877, furnishes 
 a good example of the motions of solid bodies 
 through a hardened viscid mass, taking place under 
 the influence of weight. The black wax that 
 shoemakers and boatbuilders use, is a kind of resin 
 extracted from the pine and other resinous trees, 
 melted in water, and separated from the more fluid 
 part which rises from it. Its colour is due to the 
 lampblack produced by the combustion of straw and 
 fragments of bark. At an ordinary temperature it is 
 a mass so hard that it cannot always be easily 
 scratched by the finger-nail ; but if it is left to itself 
 in a receptacle, it finally yields, spreads out as if it 
 were a liquid, and conforms to the shape of the vessel. 
 Suppose we place within a cavity hollowed out of a 
 piece of wood a portion of this substance, and keep it 
 there by means of a few pebbles, having previously 
 placed at the bottom of the cavity a few fragments of 
 some light substance, such as cork. The piece of wax 
 is thus between a light body below and a heavy body 
 above. If we wait a few days, this order is reversed 
 the wax has filled the cavity by conforming to it; 
 the cork has passed through the wax and appears on
 
 272 LIFE AND DEATH. 
 
 the surface, while the stones are at the bottom. We 
 have here the celebrated experiment of the flask with 
 the three elements, in which are seen the liquids 
 mercury, oil, and water superposed in the order of 
 their density, but in this case demonstrated with 
 solid bodies. 
 
 Influence of Diffusion. Diffusion, which dissemin- 
 ates liquids throughout each other, may also cause 
 solids to pass through other solids. Of this W. 
 Roberts Austen gave a convincing proof. This in- 
 genious physicist placed a little cylinder of lead upon 
 a disc of gold, and kept the whole at the temperature 
 of boiling water. At this temperature both metals 
 are perfectly solid, for the melting point of gold is 
 1, 200 C, and of lead is 330. Still, after this contact 
 has been prolonged for a month and a half, analysis 
 shows that the gold has become diffused through the 
 top of the cylinder of lead. 
 
 Influence of Rlectrolysis. Electrolysis offers another 
 no less remarkable means of transportation. By its 
 means we may force metals, such as sodium or lithium, 
 through glass walls. The experiment may be per- 
 formed as indicated by M. Charles Guillaume. A 
 glass bulb containing mercury is placed in a bath of 
 sodium amalgam, and a current is then made to pass 
 from within outward. After some time it can be 
 shown that the metal has penetrated the wall of the 
 bulb, and has become dissolved within it. 
 
 Influence of Mechanical Pressure, Mechanical pres- 
 sure is also capable of causing one metal to pass into 
 another. We need not recall the well-known experi- 
 ment of Cailletet, who, by employing considerable 
 pressure, caused mercury to sweat through a block of 
 iron, In a more simple manner W. Spring showed
 
 EVOLUTION AND MUTABILITY OF MATTER. 273 
 
 that a disc of copper could be welded to a disc of tin 
 by pressing them strongly one against the other. Up 
 to a certain distance from the surfaces of contact 
 a real alloy is formed; a layer of bronze of a certain 
 thickness unites the two metals, and this could not 
 take place did not the particles of both metals 
 mutually interpenetrate. 
 
 4. INTERNAL ACTIVITY OF ALLOYS. 
 
 Structure of Alloys. Metallic alloys have a re- 
 markable structure, which is essentially mobile, and 
 which we have only now begun to understand by the 
 aid of the microscope. Microscopical examination 
 justifies to a certain degree Coulomb's conjecture. 
 That illustrious physicist explained the physical pro- 
 perties of metals by imagining them to be formed of 
 two kinds of elements integral particles, to which the 
 metal owes its elastic properties, and a cement which 
 binds the particles, and to which it owes its coherence. 
 M. Brillouin has also taken up this hypothesis of 
 duality of structure. The metal is supposed to be 
 formed of very small, isolated, crystalline grains, 
 embedded in an almost continuous network of viscous 
 matter. A more or less compact mass surrounding 
 more or less distinct crystals is the conception which 
 may be formed of an alloy. 
 
 Changes of Structure produced by Deforming 
 Agencies. It has been shown that profound changes 
 of crystalline structure can be produced by various 
 mechanical means, such as hammering, and the 
 stretching of metallic bars carried to the point of 
 rupture. Some of these changes are very slow, and 
 it is only after months and years that they are com-
 
 274 LIFE AND DEATH. 
 
 pleted, and the metal attains the definite equilibrium 
 corresponding to the conditions to which it is exposed. 
 Though there may be discussions concerning the 
 extent of the transformations to which it is subjected, 
 though some believe they affect the chemical con- 
 dition of the alloy, while others limit its power to 
 physical effects, it is nevertheless true and this 
 brings us back to our subject that the mass of these 
 metals is at work, and that it only slowly attains the 
 phase of complete repose. 
 
 TJie Slow Re-establishment of Equilibrium. Re- 
 sidual Effect. These operations by which the physical 
 characters of metals are changed, and by which they 
 are adapted to a variety of industrial needs com- 
 pression, hammering, rolling, stretching, and torsion 
 have an immediate, very apparent effect; but they 
 have also a consecutive effect, slowly produced, much 
 less marked and less evident. This is the " residual 
 effect," or " Nachwirkung" of the Germans. It is not 
 without importance, even in practical applications. 
 
 Heat also creates a kind of forced equilibrium. 
 This becomes but slowly modified, so that a body 
 may remain for a long time in a state which is, how- 
 ever, not the most stable for the conditions under 
 which it is considered. The number of these bodies 
 not in equilibrium is as great as that of the substances 
 which have been exposed to fusion. All the Plutonic 
 rocks are in this condition. Glass presents a con- 
 dition of the same kind. Thermometers placed in 
 melting ice do not always mark the zero Centigrade. 
 This displacement of the zero point falsifies all 
 records if care is not taken to correct it. The 
 correction usually requires prolonged observation. 
 The theory of the displacement of the thermometric
 
 EVOLUTION AND MUTABILITY OF MATTER. 2J5 
 
 zero is not entirely established ; but we may suppose, 
 with the author of the Traite de T/urmomctrie, that in 
 glass, as in alloys, are to be found compounds which 
 vary according to the temperature. At each tem- 
 perature glass tends to assume a determinate com- 
 position and a corresponding state of equilibrium ; 
 but the previous temperature to which it has been 
 subjected clearly has an influence on the rapidity 
 with which it attains its state of repose. The effect 
 of variation is more marked when we observe, glass ot 
 more complicated composition. We can understand 
 that those which contain comparable quantities of the 
 two alkalies, soda and potash, may be more subject 
 to these modifications than those having a more 
 simple composition based on a single alkali. 
 
 Effects of Annealing. A piece of brass wire that 
 has been drawn and then heated is the scene of 
 certain very remarkable internal changes, and these 
 have been only recently recognized. The violent 
 treatment of the metallic thread in forcing it through 
 the hole -in the die has crushed the crystalline 
 particles; the interior state of the wire is that of 
 broken crystals embedded in a granular mass. 
 Heating changes all that The crystals separate, 
 repair themselves, and are built up again; they are 
 then hard, geometrical bodies, in an amorphous, 
 relatively soft and plastic mass; their number keeps 
 on increasing; equilibrium is not established until the 
 entire mass is crystallized. We may imagine how 
 many displacements, enormous when compared with 
 their dimensions, the molecules have to undergo when 
 passing through the resisting mass, and arranging 
 themselves in definite places in the crystalline 
 structures.
 
 276 LIFE AND DEATH. 
 
 in the same way, too, in the manufacture of steel, 
 the particles of coal at first applied to the surface 
 pass through the iron. 
 
 This faculty of molecular displacement enables the 
 metal in some cases to modify its state at one point 
 or another. The use made of this faculty under 
 certain circumstances is very curious, greatly re- 
 sembling the adaptation of an animal to its environ- 
 ment, or the methods of defence against agents that 
 might destroy it. 
 
 Effect of Stre telling. Hartmann's Experiment. 
 When a cylindrical rod of metal, held firmly at either 
 end a test-piece, as it is called in metallurgy is 
 pulled sufficiently hard, it often elongates consider- 
 ably, part of the elongation disappearing as soon as 
 the strain ceases, and the other part remaining. The 
 total elongation is thus the sum of an " elastic 
 elongation," which is temporary, and a " permanent 
 elongation." If we continue the stretching, there 
 appears at some point of the rod a local extension 
 with contraction of sectional area. It is here that the 
 rod will break. 
 
 But in place of continuing the stretching, Mr. 
 Hartmann suspends it. He stops, as if to give the 
 "metal-being" time to rally. During this delay it 
 would seem that the molecules hasten to the menaced 
 point to reinforce and harden the weak part. In 
 fact the metal, which was soft at other points, at 
 this spot looks like tempered metal. It is no longer 
 extensible. 
 
 When the experimenter begins the stretching again 
 after this rest, and after the narrowed bar has been 
 rolled and become cylindrical again, the local ex- 
 tension and sectional contraction is forced to occur at
 
 EVOLUTION AND MUTABILITY OF MATTER. 2J7 
 
 another point. If another rest is given at this point 
 the metal will also become hardened. 
 
 If we repeat the experiment a sufficient number of 
 times, we shall find a total transformation of the rod, 
 which becomes hardened throughout its entire extent. 
 It will break rather than elongate if the stretching is 
 sufficiently severe. 
 
 Nickel Steels their "Heroic'"' Resistance. Nickel 
 steels present this phenomena in an exaggerated 
 degree. The alternation of operations which we 
 have just described, bringing the various parts of an 
 ordinary steel rod into a tempered state, is not 
 necessary with nickel steel. The effect is produced 
 in the course of a single trial. As soon as there is 
 any tendency to contraction the alloy hardens at that 
 precise place ; the contraction is hardly noticeable ; 
 the movement is stopped at this point to attack 
 another weak point, stops there again and attacks a 
 third, and so on ; and, finally, the paradoxical fact 
 appears that a rod of metal which was in a soft state 
 and could be considerably elongated has now become 
 throughout its whole extent as hard, brittle, and 
 inextensible as tempered steel. It is in connection 
 with this point that M. C. E. Guillaume spoke of 
 ' heroic resistance to rupture." It would seem, in 
 fact, as if the ferro-nickel bar had reinforced each 
 weak point as it was threatened. It is only at the 
 end of these efforts that the inevitable catastrophe 
 occurs. 
 
 Effect of Temperature. When the temperature 
 changes, it is seen that these ferro-nickel bars elongate 
 or retract, modifying at the same time their chemical 
 constitution. But these effects, like those which occur 
 in the glass bulb of a thermometer, do not occur
 
 278 LIFE AND DEATH. 
 
 at once. They are produced rapidly for one part, and 
 more slowly for a small remaining portion. Bars of 
 ferro-nickel which have been kept at the same 
 temperature change gradually in length in the course 
 of a year. Can we find a better proof of internal 
 activity occurring in a substance differing so greatly 
 from living matter? 
 
 Nature of the Activity of Particles. These are 
 examples of the internal activity that occurs in brute 
 bodies. Besides, these facts that we are quoting 
 merely to refute Bichat's assertion relative to the 
 immutability of brute bodies, and to show us their 
 activity, also afford us another proof. They show 
 that this activity, like that of animals, wards off 
 foreign intervention, and that this parrying of the 
 attack, again like that of animals, is adapted for the 
 defence and preservation of the brute mass. So that 
 if we consider of special importance the adaptative, 
 teleological characteristic of vital phenomena, a 
 characteristic which is so easily made too much of 
 in biological interpretations, we may also find it 
 again in the inanimate world. To this end we may 
 add to the preceding examples one more which is 
 no less remarkable. This is the famous case of 
 Becquerel's process for colour-photography. 
 
 Colour-PhotograpJiy. A greyish plate, treated with 
 chloride or iodide of silver and exposed to a red light, 
 rapidly becomes red. It is then exposed to green 
 light, and after passing through dull and obscure 
 tints it becomes green. To explain this remarkable 
 phenomenon, we cannot improve on the following 
 statement: The silver salt protects itself against 
 the light that threatens its existence ; that light 
 causes it to pass through all kinds of stages of
 
 EVOLUTION AND MUTABILITY OF MATTER. 279 
 
 coloration before reducing it ; the salt stops at the 
 stage which protects it best It stops at red, if it is 
 red light that assails it, because in becoming red by 
 reflection it best repels that light i.e., it absorbs it 
 the least 
 
 It may then be advantageous, for the compre- 
 hension of natural phenomena, to regard the trans- 
 formation of inanimate matter as manifestations of a 
 kind of internal life. 
 
 Conclusion. Relations of the Surrounding Medium 
 to the Living Being and the Brute Body. Brute 
 bodies, then, are not immutable any more than are 
 living bodies. Both depend on the medium that 
 surrounds them, and they depend upon it in the 
 same way. Life brings together, brings into conflict, 
 an appropriate organism and a suitable environment. 
 Auguste Comte and Claude Bernard have taught 
 us that vital phenomena result from the reciprocal 
 action of these two factors which are in close corre- 
 lation. It is also from the reciprocal action of the 
 environment and the brute body that inevitably 
 result the phenomena which that body presents. 
 The living body is sometimes more sensitive to 
 variations of the ambient medium than is the brute 
 body, but at other times the reverse is the case. 
 For example, there is no living organism as im- 
 pressionable to any kind of stimulus whatever as the 
 bolometer is to the slightest variations of temperature. 
 
 There can only be, then, one chemically immutable 
 body namely, the atom of a simple body, since, by 
 its very definition, it remains unaltered and intangible 
 in combinations. This notion of an unalterable atom 
 has, however, itself been attacked by the doctrine of 
 the ionization of particles due to Sir J. J. Thomson; 
 
 19
 
 280 LIFE AND DEATH. 
 
 and besides, with very few exceptions those of 
 cadmium, mercury, and the gases of the argon series 
 the atoms of simple bodies cannot exist in a free 
 state. 
 
 Thus, as in the vital struggle, the ambient medium 
 by means of alimentation furnishes to the living being, 
 whether whole or fragmentary, the materials of its 
 organization and the energies which it brings into play. 
 It also furnishes to brute bodies their materials and 
 their energies. 
 
 It is also said that the ambient medium furnishes 
 to the living being a third class of things, the 
 stimuli of its activities i.e., its "provocation to action." 
 The protozoon finds in the aquatic environment 
 which is its habitat the stimuli which provoke it to 
 move and to absorb its food. The cells of the 
 metazoon encounter in the same way in the lymph, 
 the blood, and the interstitial liquids which bathe 
 them, the shock, the stimulus which brings their 
 energies into play. They do not derive from them- 
 selves, by a mysterious spontaneity without parallel 
 in the rest of nature, the capricious principle which 
 sets them in motion. 
 
 Vital spontaneity, so readily accepted by persons 
 ignorant of biology, is disproved by the whole history 
 of the science. Every vital manifestation is a response 
 to a stimulus, a provoked phenomenon. It is un- 
 necessary to say this i-s also the case with brute 
 bodies, since that is precisely the foundation of the 
 great principle of the inertia of matter. It is plain 
 that it is also as applicable to living as to inanimate 
 matter.
 
 CHAPTER V. 
 SPECIFIC FORM. LIVING BODIES AND CRYSTALS. 
 
 I. Specific form and chemical constitution The wide dis- 
 tribution of crystalline forms Organization of crystals 
 Law of relation between specific form and chemical 
 constitution Value of form as a characteristic of brute 
 and living beings Parentage, living beings and mineral 
 parentage Iso-morphism and the faculty of cross-breeding 
 Other analogies. 2. Acquisition and re-establishment 
 of the specific form Mutilation and regeneration of crystals 
 Mechanism of reparation. 
 
 I. Specific Form and Clumical Constitution. In 
 the enumeration which we have made of the essential 
 features of vitality there are three that are, so to 
 speak, of the highest value. They are, in the order of 
 their importance : The possession of a specific form ; 
 the faculty of growth or nutrition : and finally, the 
 faculty of reproduction by generation. By restricting 
 our comparison between brute bodies and living 
 bodies to these truly fundamental characters we 
 sensibly restrict the field, but we shall see that it 
 does not disappear. 
 
 Wide Distribution of Crystalline Forms. The 
 consideration of specific forms shows us that in 
 the mineral world we need only consider crystallized 
 bodies, as they are almost the only ones that possess 
 definite form. In restricting ourselves to this category 
 we do not limit our field as much as might be sup- 
 28l
 
 282 LIFE AND DEATH. 
 
 posed. Crystalline forms are very widely distributed. 
 They are, in a measure, universal. Matter has a 
 decided tendency to assume these forms whenever the 
 physical forces which it obeys act with order and 
 regularity, and when their action is undisturbed by 
 accidental occurrences. In the same way, too, living 
 forms are only possible in regulated environments, 
 under normal conditions, protected from cataclysms 
 and convulsions of nature. 
 
 The possession of a specific form is the most 
 significant feature of an organized being. Its 
 tendency, from the time it begins to develop from 
 the germ, is toward the acquirement of that form. 
 The progressive manner in which it seeks to realize 
 its architectural plan in spite of the obstacles and 
 difficulties that arise healing its wounds, repairing 
 its mutilations all this, in the eyes of the philo- 
 sophical biologist, forms what is perhaps the most 
 striking characteristic of a living being, that which 
 best shows its unity and its individuality. This 
 property of organogenesis seems pre-eminently the 
 vital property. It is not so, however, for crystalline 
 bodies possess it in an almost equal degree. 
 
 The parallel between the crystal and a living being 
 has been often drawn. I will not reproduce it here 
 in detail. My sole desire, after sketching its principal 
 features, is to call attention to the new information 
 that has been brought out by recent investigations. 
 
 Organization of Crystals. Vieivs of Hatty, Delafossc, 
 Bravais, and of Wallerant. In botany, zoology, 
 and crystallography we understand by form an 
 assemblage of material constituents co-ordinated in 
 a definite system i.e., the organization itself. The 
 body of man, for example, is an edifice in which sixty
 
 SPECIFIC FORM. ^ 
 
 trillion cells ought each to find its own predetermined 
 z ' ~~ : : 
 
 In crystallography also we understand by form the 
 organization which crystals present. The grouping 
 of the elements of crystals is, perhaps, more simple. 
 They are none the less organized, in the same sense 
 that living bodies are. 
 
 Their organization, while more uniform than that 
 of living bodies, still shows a considerable amount of 
 variation. It should not be assumed that the area of 
 a- crystal is completely filled, with contiguous parts 
 applied one to the other by plane faces, as might be 
 supposed from the phenomenon of cleavage which 
 dissociates the parts of the crystalline body into 
 solids of this kind. In reality, the constituent parts 
 are separated from each other by spaces. They are 
 arranged in a quincunx, as Hauy put it, or along the 
 lines of a network, to use the terms of Delafosse and 
 Bravais. The intervals left between them are incom- 
 parably larger than their diameters. So that in the 
 organization of a crystal it is necessary to take into 
 account two quite different things : An element; the 
 crystalline particle, which is a certain aggregate of 
 chemical molecules having a determinate geometrical 
 form ; and a more or less regular, parallelopipedic net- 
 work, along the edges of which are arranged in a con- 
 stant and definite manner the aforesaid particles. The 
 external form of the crystal indicates the existence 
 of the network. Its optical properties depend upon 
 the action of the particles, as Wallerant has shown : 
 Thus we must distinguish in a crystal between two 
 kinds of geometrical figures that of the network 
 and that of the particle and their characters of 
 symmetry may be either concordant or discordant
 
 284 LIFE AND DEATH. 
 
 The crystalline particle, the element of the crystal, 
 is therefore a certain molecular complex that repeats 
 itself identically and is identically placed at the 
 nodes of the parallelopipedic network. It has been 
 given different names well calculated to produce 
 confusion the crystallographic molecule of Mallard, 
 the complex particle of other authors. Some have 
 separated this element into subordinate elements 
 (the fundamental particles of Wallerant and of 
 Lapparent). 
 
 These very general outlines will suffice to show 
 how complex and adjustable is the organization of 
 the crystalline individual, which in spite of its 
 geometric regularity and its rigidity, may be com- 
 pared with the still more flexible organization of the 
 living element. The mineral individual is more 
 stable, more labile i.e., less prone to undergo change 
 than is the living individual. We may say with 
 M. Lapparent that " crystallized matter presents the 
 most perfect and stable orderly arrangement of 
 which the particles of bodies are susceptible." 
 
 Law of Relation of Specific Form to Chemical 
 Constitution. Crystallization is a method of acquiring 
 specific form. The geometrical architecture of the 
 mineral individual is but little less wonderful or 
 characteristic than that of the living individual. Its 
 form is the result of the mutual reactions of its 
 substances and of the medium in which it is pro- 
 duced ; it is the condition of material equilibrium 
 corresponding to a given situation. This idea of a 
 specific form belonging to a given substance under 
 given conditions must be borne in mind. We may 
 consider it as a kind of principle of nature, an 
 elementary law, which may serve as a point of
 
 SPECIFIC FORM.- 285 
 
 departure for the explanation of phenomena. A 
 particular substance under identical conditions of 
 environment, must always assume a certain form. 
 
 This close linking of substance and form, admitted 
 as a postulate in physical sciences, has been carried 
 into biology by some philosophical naturalists, by 
 M. Le Dantec, for instance 
 
 Let us imitate them for a moment. Let us cease 
 to seek in the living being for the prototype of the 
 crystal ; let us, on the contrary, seek in the crystal the 
 prototype of the living being. If we succeed in this, 
 we shall then have found the physical basis of life. 
 
 Let us say, then, with the biologists we have 
 mentioned, that the substance of each living being is 
 peculiar to it ; that it is specific, and that its form 
 that is to say its organization follows from it The 
 morphology of any being whatever, of an animal 
 of a setter, for example or even of a determinate 
 being of Peter, of Paul is the " crystalline form of 
 their living matter." It is the only form of equili- 
 brium that can be assumed under the given conditions 
 by the substance of the setter, of Peter, or of Paul, 
 just as the cube is the crystalline form of sea-salt 
 In this manner these biologists have supposed that 
 they could carry back the problem of living form 
 to the problem of living substance, and at the same 
 time reduce the biological mystery to the physical 
 mystery. I have shown above (Chap. V. pp. 199-204; 
 how far this idea is legitimate, and how far and with 
 what restrictions it may be welcomed and adopted. 
 
 Value of Form as a Characteristic of Living and 
 Brute Beings. However this may be, we may say, 
 without fear of exaggeration, that the crystalline form 
 characterizes the mineral with no less precision than
 
 286 LIFE AND DEATH. 
 
 the anatomical form characterizes the animal and the 
 plant. In both cases, form regarded as a method 
 of distribution of the parts indicates the individual 
 and allows us to diagnose it with more or less facility. 
 
 Parentage of Living Beings and Mineral Parent- 
 age. Still another analogy has been noted. In 
 animals and plants similarity in form indicates 
 similarity in descent, community of origin, and 
 proximity in any scheme of classification. In the 
 same way identity of crystalline form indicates 
 mineral relationship. Substances chemically analo- 
 gous show identical, geometrically superposable 
 forms, and are thus arranged in family or generic 
 groups recognizable at a glance. 
 
 Isomorphism and the Faculty of Cross-breeding. 
 And further, the possibility in the case of isomorphous 
 bodies, of their replacing each other in the same crystal 
 during the process of formation and of thus mingling, 
 so to speak, their congenital elements, may be 
 compared with the possibility of inter-breeding with 
 living beings of the same species. Isomorphism is 
 thus a kind of faculty of crossing. And as the 
 impossibility of crossing is the touchstone of taxo- 
 nomic relationship, testing it, and separating stocks 
 that ought to be separated, so the operation of 
 crystallization is also a means of separating from an 
 accidental mixture of mineral species the pure forms 
 which are blended therein. Crystallization is the 
 touchstone of the specific purity of minerals ; it is the 
 great process in chemical purification. 
 
 Other Analogies. The analogies between crystal- 
 line and living forms have been pushed still further 
 even to the verge of exaggeration. 
 
 The internal and external symmetry of animals
 
 SPECIFIC POEM. : : - 
 
 and plants has been compared to that of crystals. 
 Transitions or intergradations have been sought 
 between the rigid and faceted architecture of the 
 latter and the flexible structure and curved surface of 
 the former; the ntricolar form of Hovers of sulpi""" 
 on the one hand, and the geometrical structure of the 
 shells of radiolarians on the other, have shown a 
 exchange of typical forms between the two systems. 
 An effort has even been made to draw a parallel 
 between six of the principal types of the animal 
 kingdom and the six crystalline systems. If carried 
 as far as th*s, onr th*****^ becomes puerile. Real 
 analogies will suffice. Among these the curious facts 
 of crystaMicDe renewal come first. 
 
 2: CICATRIZATION ix LTVTXG BEINGS AXD ix 
 CRYSTALS. 
 
 We know that living beings not only possess a 
 typical architecture which they have themselves 
 constructed, bat that they defend it against de- 
 structive agencies, and that if need arise they repair 
 it. The living organism cicatrizes its wounds, repairs 
 losses of substance, regenerates more or less perfectly 
 the parts that have been removed; in other terms, 
 when it has been mutilated it tends to reconstruct 
 itself according to the laws of its own morphology. 
 This phenomenon of reconstitution or reintegration, 
 these more or less successful efforts to re-establish its 
 form and its integrity, at first appear to be a char- 
 acteristic feature of living beings. This is not tine 
 
 Mutilation and Rc-imt^raticm cf Crystals. Crys- 
 tals let us say crystalline individuals show a
 
 288 LIFE AND DEATH. 
 
 similar aptitude for repairing their mutilations. 
 Pasteur, in an early work, discussed these curious 
 facts. Other experimenters, Gernez a little later and 
 Rauber more recently, took up the same subject, but 
 could do no more than extend and confirm his 
 observations. Crystals are formed from a primitive 
 nucleus, as the animal is formed from an egg ; their 
 integral particles are disposed according to efficient 
 geometrical laws, so as to produce the typical form 
 by a constructive process that may be compared to 
 the embryogenic process which builds up the body of 
 an animal. Now this operation may be disturbed by 
 accidents in the surrounding medium or by the 
 deliberate intervention of the experimenter. The 
 crystal is then mutilated. Pasteur saw that these 
 mutilations repaired themselves. " When," said he, 
 " a crystal from which a piece has been broken off is 
 replaced in the mother liquor, we see that while it 
 increases in every direction by a deposit of crystalline 
 particles, activity occurs at the place where it was 
 broken off or deformed ; and in a few hours this 
 suffices not only to build up the regular amount 
 required for the increase of all parts of the crystal, 
 but to re-establish regularity of form in the mutilated 
 part." In other words, the work of formation of the 
 crystal is carried on much more actively at the point 
 of lesion than it would have been had there been no 
 lesion. The same thing would have occurred with a 
 living being. 
 
 Mechanism of Reparation. Gernez some years later 
 made known the mechanism of this reparation, or, at 
 least, its immediate cause. He showed that on the 
 injured surface the crystal becomes less soluble than 
 on the other facets. This is not, however, an ex-
 
 SPECIFIC FORM. 289 
 
 ceptional phenomenon. It is, on the contrary, quite 
 frequently observed that the different fares of a 
 crystal show marked differences in solubility*. This 
 is what happens in every case for the mutilated face 
 in comparison with the others; the matter is less 
 soluble there. The consequence of this is clear ; the 
 growth must preponderate on that face, since there 
 the mother liquor will become super-saturated before 
 being super-saturated for the others. We may 
 explain this result in another way. Each face of the 
 crystal in contact with the mother liquor is exposed 
 to two antagonistic actions : The matter deposited 
 upon a surface may be taken away and redissolved if, 
 for any reason whatever, such matter becomes more 
 soluble than that of the liquid stratum in contact 
 with it ; in the second place, the matter of this liquid 
 stratum may, under contrary conditions, be deposited, 
 and thus increase the body of the crystal. There is, 
 then, for each point of the crystalline facet, a positive 
 operation of deposit which results in a gain, and a 
 negative operation of redissolution which results in a 
 loss. One or the other effect predominates according 
 as the relative solubility is greater or less for the 
 matter of the facet under consideration. On the 
 mutilated surface it is diminished, deposition then 
 prevails. 
 
 But this is only the immediate cause of the 
 phenomenon ; and if we wish to know why the 
 solubility has diminished on the mutilated surface 
 Ostwald explains it to us by showing that crystal- 
 lization tends to form a polyhedron in which the 
 surface energy is a relative mimimum.
 
 CHAPTER VI. 
 
 NUTRITION IN THE LIVING BEING AND IN THE 
 CRYSTAL. 
 
 Assimilation and growth in the crystal. Methods of growth 
 in the crystal and in the living being ; intussusception ; 
 apposition. Secondary and unimportant character of the 
 process of intussusception. 
 
 I HAVE already stated (Chap. VI. p. 209) that nutrition 
 may be considered as the most characteristic and 
 essential property of living beings. Such beings arc 
 in a state of continual exchange with the surrounding 
 medium. They assimilate and dissimilate. By as- 
 similation the substance of their being increases at 
 the expense of the surrounding alimentary material, 
 which is rendered similar to that of the being itself. 
 
 Assimilation and Growth in tJie Crystal, There 
 exists in the crystal a property analogous to nutrition, 
 a kind of nutrility, which is the rudiment of this 
 fundamental property of living beings. The develop- 
 ment of a crystal starts from a primitive nucleus, the 
 germ of the crystalline individual that we will 
 presently compare to the ovum or embryo of a plant 
 or an animal. Placed in a suitable culture-medium 
 i.e., in a solution of the substance this germ 
 develops. It assimilates the matter in solution, 
 incorporates the particles of it, and increases, pre- 
 serving at the same time its form, reproducing its 
 290
 
 NUTRITION IN THE LIVING BEING. 2QI 
 
 specific type or a variety of it Its growth proceeds 
 without interruption. The crystalline individual may 
 attain quite a large size if we know how to nourish it 
 properly we might say, to fatten it. Very fre- 
 quently, at a given time, a new particle of the crystal 
 serves in its turn as a primitive nucleus, and becomes 
 the point of departure for a new crystal engrafted 
 upon the first. 
 
 Taken from its mother liquor, placed where it 
 cannot be nourished, the crystal, arrested in its 
 growth, falls into a condition of rest not without 
 analogy to that of a seed or of a reviviscent animal. 
 Its evolution is resumed with the return of favourable 
 conditions the bath of soluble matter. 
 
 The crystal is in a relation of continual exchange 
 with the surrounding medium which feeds it These 
 exchanges are regulated by the state of this medium, 
 or, more exactly, by the state of the liquid stratum 
 which is in immediate contact with the crystals. It 
 loses or it gains in substance if, for example, this 
 layer becomes heated or cooled more rapidly than the 
 crystal In a general way, it assimilates ordissimilates 
 according as its immediate environment is saturated 
 or diluted. Here, then, we have a kind of mobile 
 equilibrium, comparable, in some measure, to that of 
 the living being. 
 
 MetJiods of Growth of tJie Crystal and of the Living 
 Being. Intussusception. Apposition. In truth, there 
 seems to be a complete opposition between the crystal 
 and the living being as regards their manner of 
 nutrition and growth. In the one case the method is 
 intussusception ; in the other it is apposition. The 
 crystalline individual is all surface. Its mass is im- 
 penetrable to the nutriti\-e materials. Since only the
 
 2Q2 LIFE AND DEATH. 
 
 surface is accessible, the incorporation of similar 
 particles is possible only by external juxtaposition, 
 and the edifice increases only because a new layer of 
 stones has been added to those which were there 
 before. On the contrary, the body of an animal is a 
 mass essentially penetrable. The cellular elements 
 that compose it have more or less rounded and 
 flexible forms. Their contact is by no means perfect. 
 They have neither the stiffness nor the precision 
 of adjustment that the crystalline particles have. 
 Liquids and gases can insinuate themselves from 
 without and circulate within the meshes of this loose 
 construction. Assimilation can therefore take place 
 throughout its whole depth, and the edifice increases 
 because each stone is itself increasing. 
 
 The Secondary and Commonplace Character of the 
 Process of Intussusception, The apparent opposition 
 of these two processes is doubtless diminished if we 
 compare the simple mineral individual with the 
 elementary living unit, the crystalline particle with 
 the protoplasmic mass of a cell. Without carrying 
 analysis so far as this, it is yet easy to see that appo- 
 sition and intussusception are mechanical means 
 that living beings employ at one and the same time 
 and combine according to their necessities. The hard 
 parts of the internal and external skeleton increase 
 both by interposition and superposition, at once. It 
 is by the last method that bones increase in diameter, 
 and the shells of molluscs, the scales of reptiles and 
 fishes, and the testae of many radiate animals are 
 formed. In these organs, as in crystals, life and 
 nutrition occur at the surface. 
 
 Apposition and intussusception are then secondary, 
 mechanical arrangements having relation to the
 
 NUTRITION IN THE LIVING BEING. 2Q3 
 
 physical characters of the body solidity in the 
 crystal, semi-fluidity in the cellular protoplasm. If 
 we compare the inorganic liquid matter with the 
 semi-fluid organized matter, we recognize that the 
 addition of substance takes place in the same manner 
 in each i.e., by interposition. If we add a soluble 
 salt to a fluid, the molecules of the salt separate 
 themselves and interpose themselves between those 
 of the fluid. There is, therefore, nothing especially 
 mysterious or particularly vital about the process of 
 intussusception. Applied to fluid protoplasm, it is 
 merely the diffusion that ordinarily occurs in mixed 
 liquids.
 
 CHAPTER VII. 
 
 GENERATION IN BRUTE BODIES AND LIVING 
 BODIES. SPONTANEOUS GENERATION. 
 
 Protoplasm a substance which continues Case of the crystal- 
 Characteristics of generation in the living being Property 
 .of growth Supposed to be confined to the living being 
 Fertilization of micro-organisms Fertilization of crystals 
 Sterilization of crystalline and living media Spontaneous 
 generation of crystals Metastable and labile zones 
 Glycerine crystals Possible extinction of a crystalline 
 species Conclusion. 
 
 WE have not yet exhausted the analogies between a 
 crystal and the living being. The possession of a 
 specific form, the tendency to re-establish it by re- 
 disintegration and the existence of a kind of nutrition 
 are not sufficient to constitute complete similarity. 
 It still lacks a fundamental character, that of genera- 
 tion. Chauffard some time ago, in an attack which 
 he made upon the physiological ideas of his day, 
 aptly exhibited this weak point. " Let us disregard," 
 he said, "those interesting facts relative to the acquisi- 
 tion of a typical form facts that are common to the 
 mineral world as well as to living beings. It is none 
 the less true that the crystalline type is in no way 
 derived from other pre-existing types, and that 
 nothing in crystallization recalls the actions ot 
 ascendants and the laws of heredity." 
 
 This gap has since been filled. The work of 
 294
 
 SPONTANEOUS GENERATION. 2Q5 
 
 Gernez, of Vlotette, of Lecoq de Boisbandran, the ex- 
 periments of Ostwald and of Tammann, the observa- 
 tkxis of Crookes and of Armstrong all this series of 
 researches, so lucidly summarized by M. Leo Errera 
 in his essays in botanical philosophy, had for their 
 result die establishment of an unsuspected relation 
 between the processes of crystallization and those of 
 generation in animals and plants, 
 
 Protoplasm is a Substitute which Comtixtus. The 
 Cast of the Crystal. Under present conditions a living 
 being of any kind springs from another living being 
 similar to Itself. 
 
 Its protoplasm is always a continuation of the 
 protoplasm of an ancestor. It is an atavic substance 
 of which we do not see the beginning; we only see it 
 continue. The anatomical element comes from a 
 preceding anatomical element, and the higher animal 
 itself comes from a pre-existing cell of the material 
 organism, the ovum. The ladder of filiation reaches 
 back indefinitely into the past. 
 
 We shall see that there is something analogous to 
 this in certain crystals. They are born of a preceding 
 individual; they may be considered as the posterity 
 of the antecedent crystal If we speak of the matter 
 of a crystal as the matter of a living being is spoken 
 of, in cases of this kind we would say that the 
 crystalline substance is an atavic substance of which 
 we see only the continuation, as in the case of 
 protoplasm. 
 
 Characters of Gauratitm in the Living Betmg.^ 
 Growth of the living substance, and consequently of 
 the being itself, is the fundamental law of vitality. 
 Generation is the necessary consequence of growth 
 (p. 210} 
 
 20
 
 296 LIFE AND DEATH. 
 
 Living elements or cells cannot subsist indefinitely 
 without increasing and multiplying. The time must 
 come when the cell divides, either directly or in- 
 directly; and then, instead of one cell, there are two. 
 This is the method of generation for the anatomical 
 element. In a complex individual it is a more or less 
 restricted part of the organism, usually a simple 
 sexual cell, that takes on the formation of the new 
 being, and assures the perpetuity of the protoplasm, 
 and therefore of the species. 
 
 Property of Growth. Its Supposed Restriction to 
 Living Beings. At first it would appear that nothing 
 like this occurs in inanimate nature. The physical 
 machine, if we furnish it matter and energy, could go 
 on working indefinitely, without being compelled to 
 increase and reproduce. Here, then, there is an 
 entirely new condition peculiar to the organized 
 being, a property well' adapted, it would seem and 
 this time without any possible doubt for separating 
 living matter from brute matter. It is not so. 
 
 It would not be impossible to imagine a system 
 of chemical bodies organized like the animal or 
 vegetable economy, so that a destruction would be 
 compensated for by a growth. The only thing im- 
 possible is to suppose, with M. le Dantec, a destruction 
 that would at the same time be an analysis. And an 
 additional perplexity occurs when he supposes that 
 in the successive acts exchanges of material may 
 occur. 
 
 There is no necessity for making this impossible 
 chemistry a characteristic of the living being. The 
 chemistry of the living being is general chemistry. 
 Lavoisier and Berthelot enforced this view. We 
 should not lose sight of the teachings of the masters.
 
 SPONTANEOUS GENERATION. 297 
 
 Let us return to generation, properly so called, and 
 find in it the characteristics of brute bodies and of 
 crystals. 
 
 The Sowing of ^Hero-organisms. When a micro- 
 biologist wishes to propagate a species of micro- 
 organisms, he places in a culture medium a few 
 individuals (one is all that is actually necessary), and 
 soon observes their rapid multiplication. Usually, if 
 only the ordinary microbes in atmospheric dust are 
 wanted, the operator need not trouble to charge the 
 culture; if the culture tube remains open and the 
 medium is suitably chosen, some germ of a common 
 species will fall in and the liquid will become 
 colonized. This has the appearance of spontaneous 
 generation. 
 
 T/i Sowing of Crystals. Concentrated solutions of 
 various substances, supersaturated solutions of sodium 
 magnesium sulphate, and sodium chlorate are also 
 wonderful culture media for certain mineral organic 
 units certain crystalline germs. Ch. Dufour, ex- 
 perimenting with water cooled below O D C, its point 
 of solidification ; Ostwald, with salol kept below 39'.$, 
 its point of fusion ; Tammann, with betol, which 
 melts at 96 ; and, before them, Gernez, with melted 
 phosphorus and sulphur all these physicists have 
 shown that liquids in superfusion are also media 
 specially appropriate for the culture and propagation 
 of certain kinds of crystalline individuals. 
 
 Some of these facts have become classic. Lowitz 
 showed in 1/85 that a solution of sodium sulphate 
 could be concentrated by evaporation so as to contain 
 more salt than was conformable with the temperature, 
 without, however, depositing the excess. But if a 
 solid fragment, a crystal of salt, is thrown into the
 
 298 LIFE AND DEATH. 
 
 liquor, the whole of the excess immediately passes 
 into the state of a crystallized mass. The first 
 crystal has engendered a second similar to itself; 
 the latter has engendered a third, and so on from one 
 to the other. If we compare this phenomenon with 
 that of the rapid multiplication of a species of 
 microbes in a suitable culture medium, no difference 
 will be perceived. Or perhaps we may note one 
 unimportant difference the rapidity of the propaga- 
 tion of the crystalline germs as opposed to the relative 
 slowness of the generation of the micro-organisms. 
 
 Again, the propagation of crystallization in a super- 
 saturated or superfused liquid may be delayed by 
 appropriate devices. The crystalline individual gives 
 birth, then, to another individual that conforms to its 
 own type, or even to varieties of that type when such 
 exist. Into the right branch of a U tube filled with 
 sulphur in a state of superfusion Gernez dropped 
 octahedric crystals of sulphur, and into the left branch 
 prismatic crystals. On either side were produced 
 new crystals conforming to the type that had been 
 sown. 
 
 Sterilization of Crystalline Media and Living Media. 
 Ostwald varied these experiments by using salol. 
 He melted the substance by heating it above 39. 5 C.; 
 then, protecting it from crystals of any kind, he let 
 the solution stand in a closed tube. The salol re- 
 mained liquid indefinitely until it was touched with 
 a platinum wire that had been in contact with solid 
 salol i.e., until a crystalline germ was introduced. 
 But if the platinum wire has been previously sterilized 
 by passing it, as the bacteriologists do, through a 
 flame, it can then be introduced into the liquor with 
 impunity.
 
 SPONTANEOUS GENERATION. 299 
 
 The Dimensions of Crystalline Germs Compar- 
 able te those of Microbes. We may dilute the solid 
 salol with inert powder lactin, for example dilute 
 the first mixture with a second, the second with a 
 third, and so on; then, throwing into the solution of 
 surfused salol a tenth of a milligram from one of 
 these various mixtures, we find that the production of 
 crystals will not take place if the fragment thrown in 
 weighs less than a millionth of a milligram, or 
 measures less than ten thousandths of a millimetre 
 in length. It would seem, then, that these are the 
 dimensions of the crystalline particle or crystallo- 
 graphic molecule of salol. In the same way Ostwald 
 satisfied himself that the crystalline germ of hypo- 
 sulphite ' of soda weighs about a thousand-millionth of 
 a milligram, and measures a thousandth of a milli- 
 metre; that of chlorate of soda weighs a ten-millionth 
 of a milligram. These dimensions are entirely com- 
 parable with those of microbes. 
 
 All these phenomena have been studied with a 
 detail into which it is impossible to enter here, and 
 which clearly shows more and more intimate analogies 
 between the formation of crystals and the generation 
 of micro-organisms. 
 
 Extension and Propagation of Crystallization. 
 Optimum Temperature of Incubation. Crystallization 
 which has commenced around a germ is propagated 
 more or less rapidly, and ends by invading the whole 
 of the liquor. 
 
 The rapidity of this movement of extension depends 
 upon the conditions of the medium, especially upon 
 its temperature. This is shown very well by 
 Tammann's experiments with betol. This body, 
 the salicylic ester of naphthol, fuses at 96 C. If it
 
 300 LIFE AND DEATH. 
 
 is melted in tubes sealed at a temperature of 100 C, 
 it may be cooled to lower and lower temperatures 
 to + 70, to + 25, to + IO, to 5 without solidifying. 
 Let us suppose that by some combination of circum- 
 stances a few centres of crystallization that is to 
 say, of crystalline germs have appeared in the 
 solution. Solidification will extend slowly at the 
 ordinary temperature, at 20 to 25 and thereabouts. 
 On the other hand, it will be propagated with great 
 rapidity if the liquor is kept at about 70. This 
 point 70 is the thermal optimum for the pro- 
 pagation of germs. It is the most favourable 
 temperature for what may be called their incubation. 
 As soon as the germs find themselves in a liquor at 
 70 they increase, multiply, and show that they are in 
 the best conditions for growth. 
 
 Spontaneous Generation of Crystals. Optimum 
 Temperature for the Appearance of Germs. If we 
 consider various supersaturated solutions or liquids 
 in superfusion, we shall soon discover that they can 
 be arranged in two categories. Some remain in- 
 definitely liquid under given conditions unless a 
 crystalline germ is introduced into them. Others 
 solidify spontaneously without artificial intervention, 
 and such crystallization may even be propagated very 
 rapidly under determinate conditions. This implies 
 that these are conditions favouring the spontaneous 
 appearance of germs. 
 
 This distinction between substances of crystalline 
 generation by filiation and substances of spontaneous 
 crystalline generation is not specific. The same 
 substance may present the two methods of generation 
 according to the conditions in which it is placed. 
 Betol furnishes a good example of this. Liquefy it at
 
 SPONTANEOUS GENERATION. 30! 
 
 TOO' in a sealed tube and keep it by means of a stove 
 above 30 , and it will remain liquid almost indefinitely. 
 On the other hand, lower its temperature and leave it 
 for one or two minutes at 10", and germs will appear 
 in the liquor; prolong the exposure to this degree of 
 heat and the number of these spontaneously appearing 
 germs, appearing in isolation, will rapidly increase. 
 On the other hand, you will observe that propagation 
 by filiation that is to say, by extension from one 
 to another is almost absent. The temperature of 
 10 is not favourable to that method of generation ; 
 and we have just seen, in fact, that it is at a tem- 
 perature of about 70 that extension of crystallization 
 from one to another is best accomplished. The 
 temperature of 70" was the optimum for propagation 
 by filiation. Inversely, the temperature of 10" is the 
 optimum for spontaneous generation. Above and 
 below this optimum the action is slower. \Ve may 
 count the centres of crystallization, which slowly 
 extend further and further, as in a microbic 
 culture one counts the colonies corresponding to 
 the germs primitively formed. To sum up, if 
 there is an optimum for the formation of 
 crystals, there is a different optimum for their rapid 
 extension. 
 
 The Metastable and Labile Zones. This phenomena 
 is general. There is for each substance a set of 
 conditions (temperature, degree of concentration, 
 volume of the solution) in which the crystalline 
 individuals can be produced only by germs or by 
 filiation. This is what occurs for betol above the 
 temperature of 30". The body is then in what 
 Ostwald- has called a nietas table zone. There is, 
 however, for the same body another set of circum-
 
 3O2 LIFE AND DEATH. 
 
 stances more or less complete, in which its gems 
 appear simultaneously. This is what happens for 
 betol at about the temperatute of 10. These circum- 
 stances are those of the labile zone or zone of 
 spontaneous generation. 
 
 Crystals of Glycerine. We may go a step further. 
 Let us suppose, with L. Errera, that we have a liquid 
 in a state of metastable equilibrium, whose labile 
 equilibrium is as yet unknown. This is what actually 
 occurs for a very widely known body, glycerine. 
 We do not know under what conditions glycerine 
 crystallizes spontaneously. If we cool it, it becomes 
 viscous ; we cannot obtain its crystals in that way. 
 It was not found in crystals until 1867. In that 
 year, in a cask sent from Vienna to London during 
 winter, crystallised glycerine was found, and Crookes 
 showed these crystals to the Chemical Society of 
 London. What circumstances had determined their 
 formation ? We knew not then, and we know not 
 now. It may be observed that this case of spon- 
 taneous generation of the crystals of glycerine has 
 not remained the solitary instance. M. Henninger 
 has noted the accidental formation of glycerine 
 crystals in a manufactory in St. Denis. 
 
 It may be remarked that this crystalline species 
 appeared, as living species may have done, at a given 
 moment in an environment in which a favourable 
 chance combined the necessary conditions for its 
 production. It is also quite comparable to the 
 creation of a living species ; for having once appeared 
 we have been able to perpetuate it. The crystalline 
 individuals of 1867 have had a posterity. They 
 have been sown in glycerine in a state of superfusion, 
 and there they reproduced themselves. These
 
 SPONTANEOUS GENERATION*. 303 
 
 generations have been sufficiently numerous to 
 spread the species throughout a great part of 
 Europe. M. Hoogewerf showed a great flask full 
 to the Dutch biologists who met at Utrecht in 
 1891. M. L. Errera presented others in June 1899, 
 to the Society of Medical and Natural Sciences at 
 Brussels. To-day the great manufactory of Sarg & 
 Co., of Vienna, is engaged in their production on a 
 large scale for industrial purposes. 
 
 Thus we are able to study this crystalline species 
 of glycerine and to determine with precision the 
 conditions of its continued existence. It has been 
 shown that it does not resist a temperature of 18, so 
 that if precautions were not taken to preserve it, 
 a single summer would suffice to annihilate all the 
 crystalline individuals existing on the surface of the 
 globe, and thus the species would be extinguished. 
 
 Possible Extinction of a Crystalline Species. As 
 these crystals melt at iS 3 , this temperature represents 
 the point of fusion of solid glycerine or the point of 
 solidification of liquid glycerine. But the liquor 
 does not solidify at all if its temperature falls below 
 18 C., as we well know, for it is at that temperature 
 we use it Nor does it solidify at zero, nor even at 
 18 below zero ; at 20, for instance, it merely thickens 
 and becomes pasty. We only know glycerine, then, in 
 a state of superfusion, a fact which chemists have not 
 learned without amazement. Under these conditions, 
 so analogous to the appearance of a living species, to 
 its unlimited propagation and to its extinction, the 
 mineral world offers a quite faithful counterpart to 
 the animal world. The living body illustrates here 
 the history of the brute body and facilitates its 
 exposition. Inversely, the brute body in its turn
 
 304 LIFE AND DEATH. 
 
 throws remarkable light on the subject of the living 
 body, and on one of the most serious problems 
 relative to its origin, that of spontaneous generation. 
 
 Conclusion. These facts lead to one conclusion. 
 Until the concourse of propitious circumstances 
 favourable to their spontaneous generation was 
 brought about, crystals were obtained only by 
 filiation. Until the discovery of electro-magnetism, 
 magnets were made only by filiation, by means of 
 the simple or double application of a pre-existing 
 magnet. Before the discovery which fable attributes 
 to Prometheus, every new fire was produced only by 
 means of a spark from a pre-existing fire. We are 
 at the same historical stage as regards the living 
 world, and that is why, up to the present, there has 
 never been formed a single particle of living matter 
 except by filiation, except by the intervention of a 
 pre-existing living organism.
 
 BOOK V. 
 
 SENESCENCE AXD DEATH. 
 
 Chap. I. The different points of view from which death may be 
 regarded. Chap. II. Constitution of the organisms 
 Partial death Collective death. Chap. III. Physical 
 and chemical characteristics of cellular death Necrobiosis. 
 Chap. IV. Apparent perennity of complex individuals. 
 Chap. V. Immortality of the protozoa and of slightly 
 differentiated cdls. 
 
 WE grow old and we die. We see the beings 
 which surround us grow old and disappear. At first 
 we see no exceptions to this inexorable law, and we 
 consider it as a universal and inevitable law of 
 nature. But is this generalization well founded? 
 Is it true that no being can escape the cruel fate of 
 old age and death, to which we and all the repre- 
 sentatives of the higher animality are exposed ? Or, 
 on the other hand, are any beings immortal ? Biology 
 answers that, in fact, some beings are immortal. 
 There are beings to whose life no law assigns a 
 limit, and they are the simplest, the least differentiated 
 and the least perfect. Death thus appears to be a 
 singular privilege attached to organic superiority, the 
 ransom paid for a masterly complexity. Above these 
 elementary, monocellular, undifferentiated beings, 
 which are protected from mortality, we find others, 
 higher in their organization, which are exposed to 
 305
 
 306 LfFE AND DEATH. 
 
 it, but with whom death" seems but an accident, 
 avoidable in principle if not in fact. The anatomical 
 elements of this higher animal are a case in point. 
 Flourens once tried to persuade us that the threshold 
 of old age might be made to recede considerably, and 
 there are biologists in the present day who give us 
 some glimpse of a kind of vague immortality. We 
 may, therefore, ask our readers to follow us in our 
 examination of these re-opened if not novel questions, 
 and we shall explain the views of contemporary 
 physiology as to the nature of death, its causes, its 
 mechanisms, and its signs.
 
 CHAPTER I. 
 
 VARIOUS WAYS OF REGARDING DEATH. 
 
 Different meanings of the word death Physiological distinction 
 between elementary and general death Non-scientific 
 opinions The ordinary point of view Medical point of 
 view. The signs of death are prognostic signs. 
 
 Different Meanings oftlu WordDeatJi. An English 
 philosopher has asserted that the word we translate 
 by " cause " has no less than sixty-four different mean- 
 ings in Plato and forty-eight in Aristotle. The word 
 "death" has not so many meanings in modern 
 languages, but still it has many. Sometimes it 
 indicates an action which is taking place, the action 
 of dying, and sometimes a state, the state which 
 succeeds the action of dying. The phenomena it 
 connotes are in the eyes of many biologists quite 
 different, according as we watch them in an animal 
 of complex organization, or on the other hand, in 
 monocellular beings, protozoa and protophytes. 
 
 Physiological Distinction between Elementary Death 
 and General Death. We distinguish the death of the 
 anatomical elements, elementary death, from the 
 death of the individual regarded as a whole, general 
 deatlt. Hence we recognize an apparent death, which 
 is an incomplete and temporary suspension of the 
 phenomena of vitality, and a real death, which is a 
 final and total arrest of these phenomena. When 
 307
 
 3O8 LIFE AND DEATH. 
 
 we consider it in its essential nature (assumed, but 
 not known) we look on it as the contrary of life, as 
 did the Encyclopaedia, Cuvier, and Bichat ; or \ve 
 regard it with others either as the consequence of 
 life, or simply as the end of life. 
 
 Non-scientific Opinions. What is death to those 
 outside the realm of science ? First of all we find the 
 consoling solution given by those who believe death 
 to be the commencement of another life. We next 
 find ourselves involved in a confused medley, an 
 infinite diversity of philosophical doubt and super- 
 stition. " A leap into the unknown," says one. 
 " Dreamless and unconscious night," says another. 
 And again, " A sleep which knows no waking." 
 Or, with Horace, " the eternal exile," or with 
 Seneca, annihilation. Post mortem nitiil ; ipsaqne 
 mors nihil. 
 
 The idea which is constantly supervening in the 
 midst of this conflict of opinion is that of the 
 breaking up of the elements, the union of which 
 forms the living being. It has, as we shall see, a 
 real foundation which may perhaps receive the 
 support of science. We shall not find that the best 
 way of defining death is to say that it consists of the 
 " dissolution of the society formed by the anatomical 
 elements, or again, in the dissolution of the conscious- 
 ness that the individual possesses of himself i.c , of 
 the existence of this society." It is the rupture of 
 the social bond. The old idea of dispersion is a 
 variant of the same notion. But the ancients 
 evidently could not understand, as we do, the nature 
 of these elements which are associated to form the 
 living being, and which are liberated or dispersed 
 by death. We, as biologists, can see microscopical
 
 VARIOUS WAYS OF REGARDING DEATH. 309 
 
 organic unity with a real objective existence. The 
 ancients were thinking of spiritual elements, of 
 principles, of entities. To the Romans, who may be 
 said to have held that there are three souls, death 
 was produced by their separation from the body. 
 The first, the breath, the spiritus, mounting towards 
 celestial regions (aslra petif) ; the second, the shade, 
 remaining on the surface of the earth and wandering 
 around the tombs ; the third, the manes, descending 
 to the lower regions. The belief of the Hindoos was 
 slightly different The body returned to the earth, 
 the breath to the winds, the fire of the glance to the 
 sun, and the ethereal soul to the world of the pure. 
 Such were the ideas of mortal dispersion formed by 
 ancient humanity. 
 
 Modern science takes a more objective point of 
 view. It asks by what facts, by what observable 
 events death is indicated. Generally speaking, we 
 may say that these facts interrupt an interior state 
 of things which was life and to which they put an 
 end Thus death is defined by life. It is the 
 cessation of the events and of the phenomena which 
 characterize life. We must, therefore, know what 
 life is to understand the meaning of death. How 
 wise was Confucius when he said to his disciple, 
 Li-Kou : " If we do not know life, how can we 
 know death ? " According to biology there are two 
 kinds of death because there are two kinds of life ; 
 elementary life and death correspond just as general 
 life and death do, and this is where scientific opinion 
 diverges from commonly received opinion. 
 
 What cares the man who reasons as most human 
 beings do, about this life of the anatomical elements 
 of his body, the existence and the silent activity of
 
 3IO LIFE AND DEATH. 
 
 which are in no way revealed to him. What does 
 their death matter to him ? To him there is but one 
 poignant question, that of being separated or not 
 being separated from the society of his fellows. 
 Death is no longer to feel, no longer to think ; it is 
 the assurance that one will never feel, one will never 
 think again. Sleep, dreamless sleep, is already in our 
 eyes a kind of transient death ; but, when we fall asleep 
 we are sure of waking again. There is no awaking 
 from the sleep of death. But that is not all. Man 
 knows that death, this dreamless sleep that knows no 
 waking, will be followed by the dissolution of his 
 body. And what a dissolution will there be for the 
 body, the object of his continual care ! Remember 
 the description of Cuvier the flesh that passes from 
 green to blue and from blue to black, the part which 
 flows away in putrid venom, the other part which 
 evaporates in foul emanations, and finally, the few 
 ashes that remain, the tiny pinch of mineral?, saline 
 or earthy, which are all that is left of that once 
 animated masterpiece. 
 
 7 he Popular View. To the man afraid of death 
 it seems, in the presence of so great a catastrophe, 
 that the patient analysis of the physiologist scrupu- 
 lously noting the succession of phenomena and ex- 
 plaining their sequence is uninteresting. He will 
 only attach the slightest importance to knowing that 
 vestiges of vitality remain in this or that part of his 
 body, if they do not re-establish in every part the 
 status quo ante. He cares not to hear that a certain 
 time after the formal declaration of his death his 
 nails and his hair will continue to grow, that his 
 muscles will still have the useless faculty of con- 
 traction, that every organ, every tissue, every element,
 
 VARIOUS WAYS OF REGARDING DEATH. 311 
 
 will oppose a more or less prolonged resistance to the 
 invasion of death. 
 
 Medical Vicm. It is, however, these very facts and 
 details, this why and wherefore, which interest the 
 physiologist. The state of mind of the doctor in this 
 respect, again, is different When, for instance, the 
 doctor declares that such and such a person is dead, 
 he is really making not so much a statement of fact 
 as a prediction. How many elements are still living 
 and will be capable of new birth in this corpse that 
 he has before his eyes? That is not what he asks 
 himself, nor is it what we should ask of him. He 
 knows, besides, that all these partial survivals will be 
 extinguished and will never find the conditions 
 necessary to reviviscence, and that the organization 
 will never be restored to its primal activity ; and this 
 is what he affirms. The fear of premature burial 
 which haunts so many imaginations is the fear of an 
 error in the prediction. It is to avoid this that 
 practical medicine has devoted so much of its 
 attention to the discovery of a certain and early 
 sign of death. By this we understand the discovery 
 of a certain prognostic sign of general death. We 
 want a prognostic sign enabling us to assert that the 
 life of the brain is now extinguished and will never 
 be reanimated. And yet there are in that organism 
 many elements which are still alive. Many others 
 even may be born anew if we could give them 
 suitable conditions which they no longer meet with 
 in the animal machine now thrown out of gear. 
 What finer example could we give than the experi- 
 ment of Kuliabko, the Russian physiologist, who 
 kept a man's heart working and beating for eighteen 
 hours after the official verification of his death. 
 
 21
 
 CHAPTER II. 
 
 THE PROCESS OF DEATH. 
 
 Constitution of organisms. Partial lives. Collective life. The 
 role of apparatus. Death by lesion of the major appar- 
 atus. The vital tripod. Solidarity of the anatomical 
 elements. Humoral solidarity. Nervous solidarity. In- 
 dependence and subordination of the anatomical elements. 
 
 Partial Lives. Collective Life. With the exception 
 of the physiologist, no one, neither he who is ignorant 
 nor he who is intellectual, nor even the doctor, 
 troubles his head about the life or the death of the 
 element, although this is the basis, the real founda- 
 tion, of the activity manifested by the social body 
 and by its different organs. The life of the indi- 
 vidual, of the animal, depends on these elementary 
 partial lives just as the existence of the State depends 
 upon that of its citizens. To the physiologist, the 
 organism is a federation of cellular elements unified 
 by close association. Goethe compared them to a 
 " multitude " ; Kant to a " nation " ; and others have 
 likened them to a populous city the anatomical 
 elements of which are the citizens, and which pos- 
 sesses an individuality of its own. So that the 
 activity of the federated organism may be discussed 
 in each of its parts, and then it is elementary life, or 
 in its totality, and then it is general life. Paracelsus 
 and Bordeu had a glimpse of this truth when they 
 considered a life appropriate to each part (vita proprid] 
 312
 
 THE PROCESS OF DEATH. 313 
 
 and a collective life, the life of the whole {vita 
 communist In the same way we must distinguish 
 the elementary death, which is the cessation of the 
 vital phenomena in the isolated cell, from the general 
 death, which is the disappearance of the phenomena 
 which characterised the collectivity, the totality, the 
 federation, the nation, the city, the whole in so far as 
 it is a unit 
 
 These comparisons enable us to understand how 
 general life depends on the partial lives of each 
 anatomical citizen. If all die, the nation, the federa- 
 tion, the total being clearly ceases to exist This 
 city has an enormous population there are thirty 
 trillion cellules in the body of man ; it is peopled 
 with absolutely sedentary citizens, each of which has 
 its fixed place, which it never leaves, and in which it 
 lives and dies. It must possess a system of more or 
 less perfect arrangements to secure the material life 
 of each inhabitant All have analogous require- 
 ments : they feed very much the same ; they breathe 
 in the same way; each in fact has its profession, 
 industry, talents, and aptitudes by which it contri- 
 butes to social life, and on which, in its turn, it 
 depends. But the process of alimentation is the 
 same for all. They must have water, nitrogenous 
 materials and analogous ternaries ; the same mineral 
 substances, and the same vital gas, oxygen. It is no 
 less necessary that the wastes and the egesta, very 
 much alike in every respect, should be carried off and 
 borne away in discharges arranged so as to free the 
 whole system from the inconvenience, the unhealthi- 
 ness, and the danger of these residues. 
 
 Secondary Organisation in Organs. That is why, 
 as we said above, the secondary organizations of the
 
 314 LIFE AND DEATH. 
 
 economy exist : the digestive apparatus which pre- 
 pares the food and enables it to pass into the blood, 
 into the lymph, and finally into the liquid medium 
 which bathes each cell and constitutes its real 
 medium ; the respiratory apparatus which imports 
 the oxygen and exports the gaseous excrement, 
 carbonic acid ; the heart and the circulatory system 
 which distributes through the system the internal 
 medium, suitably purified and recuperated. The 
 organization is dominated by the necessities of 
 cellular life. This is the law of the city, to which 
 Claude Bernard has given the name of the laiv of the 
 constitution of organisms. 
 
 Death by Lesion of the Major Organs. Vital 
 Tripod. Thus we understand what life is, and at the 
 same time what is the death of a complex living 
 being. The city perishes if its more or less compli- 
 cated mechanisms which look after its revictualling 
 and its discharge are seriously affected at any point 
 The different groups may survive for a more or less 
 lengthy period, but progressively deprived of the 
 means of food or of discharge, they are finally 
 involved in the general ruin. If the heart stops, 
 there is a universal famine ; if the lungs are seriously 
 injured, we are asphyxiated ; if the principal organ 
 of discharge, the kidney, ceases to perform its allotted 
 task, there is a general poisoning by the used-up and 
 toxic materials retained in the blood. 
 
 We understand how the integrity of the major 
 organs, the heart, the lungs, the kidney, is indis- 
 pensable to the maintenance of existence. We 
 understand that their lesion, by a series of successive 
 repercussions, involves universal death. We always 
 die, said the doctors of old, because of the failure of
 
 THE PROCESS OF DEATH. 315 
 
 one of these three organs, the heart, th 2 lungs, or the 
 brain. Life, they said in their inaccurate language, 
 depends upon these as upon three supports. Hence 
 the idea of the vital tripod. But it is not only this 
 trio of organs which maintain the organism ; the 
 kidney and the liver are no less important In 
 different degrees each part exercises its action on the 
 rest. Life is based in reality on the immense 
 multitude of living cells associated for the formation 
 of the body ; on the thirty trillion anatomical ele- 
 ments, each part is more or less necessary to all the 
 rest, according as the bond of solidarity is drawn more 
 or less closely in the organism under consideration. 
 
 Death and the Brain. There are indeed more noble 
 elements charged with higher functions than the rest 
 These are the nervous elements. Those of the brain 
 preside over the higher functions of animality, sensi- 
 bility, voluntary movement, and the exercise of the 
 intellect. The rest of the nervous system forms an 
 instrument of centralization which establishes the 
 relations of the parts one with the other and secures 
 their solidarity. When the brain is stricken and its 
 functions cease, man has lost the consciousness of his 
 existence. Life seems to have disappeared. We say 
 of a man in this plight that he no longer lives, thus 
 confusing general life with the cerebral life which is 
 its highest manifestation. But the man or the 
 animal without a brain lives what may be called a 
 vegetative life. The human anencephalic foetus lives 
 for some time, just as the foetus which is properly 
 formed. Observation always shows that this exist- 
 ence of the other parts of the body cannot be sus- 
 tained indefinitely in the absence of that of the brain. 
 By a series of impulses due to the solidarity of the
 
 3l6 LIFE AND DEATH. 
 
 grouping of the parts, the injury received by the 
 brain affects by repercussion the other organs, and 
 leads in the long run to the arrest of elementary life 
 in all the anatomical elements. The death of the 
 whole is then complete. 
 
 Doctors have therefore a two-fold reason for saying 
 that the brain may cause death. The death of the 
 brain suppresses the- highest manifestation of life, and, 
 in the second place, by a more or less remote counter 
 stroke, it suppresses life in all the rest of the system. 
 
 Death is a Process. Besides, the fact is general. 
 The death of one part always involves the death of 
 the rest i.e., universal death. A living organism 
 cannot be at the same time alive and a cemetery. The 
 corpses cannot exist side by side with the living 
 elements. The dead contaminates the living, or in 
 some other way involves it in its ruin. Death is 
 propagated ; it is a progressive phenomenon which 
 begins at one point and gradually is extended to the 
 whole. It has a beginning and a duration. In other 
 words, the death of a complex organism is a process. 
 And further, the end of a simple organism, of a 
 protozoan, of a cell, is itself a process infinitely 
 more shortened. 
 
 The very perfection of the organism is therefore the 
 cause of its fragility. It is the degree of solidarity of 
 the parts one with another which involves the one set 
 in the catastrophe of the rest, just as in a delicate 
 piece of mechanism the derangement of a wheel brings 
 nearer and nearer the total breakdown. The im- 
 portant parts, the lungs, the heart, the brain, suffer no 
 serious alteration without the reflex being felt through- 
 out. But there are also wheels less evident, the 
 integrity of which is scarcely less necessary.
 
 THE PROCESS OF DEATH. 317 
 
 Tlu Solidarity of tJu Anatomical Elements. The 
 cause of the mortal process />., of the extension and 
 the propagation of an initial destruction is therefore 
 to be found in the solidarity of the parts of the 
 organism. The closer it is the greater do the chances 
 of destruction become, for the accident which has 
 happened to one will by repercussions affect the 
 others. 
 
 Now the solidarity of the parts of the organism 
 may be carried out in two ways ; there is a Jtumoral 
 solidarity and a nervous solidarity. 
 
 Humoral Solidarity. Humoral solidarity is realized 
 by the mixture of humours. All the liquids of the 
 organism which have lodged in the interstices of the 
 elements and which soak the tissues, are in contact 
 and in relation of exchange one with another, and 
 through the permeable wall of the small vessels they 
 are in relation with the blood and the lymph. 
 
 All the liquid atmospheres which surround the 
 cells and form their ambient medium have inter- 
 communication. A change having taken place in one 
 cellular group, and therefore in the corresponding 
 liquid, modifies the medium of the further or nearer 
 groups, and therefore these groups themselves. 
 
 Nervous Solidarity. But the real instrument of the 
 solidarity of the part is the nervous system. Thanks 
 to it in the living machine the component activities of 
 the cellular multitude restrain and control one another. 
 Nervous solidarity makes of the complex being not a 
 mob of cells, but a connected system, an individual in 
 which the parts are subordinated to the whole and the 
 whole to the parts ; in which the social organism has 
 its rights just as the individual has his rights. The 
 whole secret of the vital functional activity of the
 
 318 LIFE AND DEATH. 
 
 complex being is contained in these two factors : the 
 independence and the subordination of the elementary 
 lives. General life is the harmony of the elementary 
 lives, their symphony. 
 
 Independence and Subordination of the Anatomical 
 Elements. The independence of the anatomical ele- 
 ments results from the fact that they are the real 
 depositaries of the vital properties, the really active 
 components. On the other hand the subordination of 
 the parts to the whole is the very condition of the 
 preservation of form in animals and plants. The 
 architecture which is characteristic of them, the 
 morphological plan which they realize in their 
 evolutive development which they are ever preserving 
 and repairing, form a striking proof of this. This 
 dependence in no way contradicts the autonomy of 
 the elements. For when with Claude Bernard and 
 Virchow we study the circumstances we see that 
 the element accommodates itself to the organic 
 plan without violence to its nature. It behaves 
 in its natural place as it would behave elsewhere, 
 if elsewhere it were to meet around it the 
 same liquid medium which at once is a stimulant 
 and a food. This at least is the conclusion we 
 may draw from experiments on transplanting, or 
 on animal and vegetable grafting. Neither the 
 neighbouring elements, nor the whole system act on it 
 at a distance by a kind of mysterious induction, 
 according to the ideas of the vitalists, in order to 
 regulate the activity of the element. They contribute 
 solely to the composition of the liquid atmosphere 
 which bathes it. They intervene in order to provide 
 it with a certain environment whose very characteristic 
 physical and chemical constitution regulates its
 
 THE PROCESS OF DEATH. 319 
 
 activity. This constitution may be some day imitated 
 by the devices of experiment When that result is 
 achieved the anatomical element will live in isolation 
 exactly as it lives in the organic association, and the 
 mysterious bond which causes its solidarity with the 
 rest of the economy will become intelligible. In fact, 
 we may defer more or less the maturity of this 
 prophecy, but there is no doubt that we are daily 
 nearing its fulfilment. 
 
 The general life of the complex being is therefore 
 the more or less perfect synergy, the ordered process of 
 elementary lives. General death is the destruction of 
 these partial lives. The nervous system, the instru- 
 ment of this harmony of the parts, represents the 
 social bond. It keeps most of the partial elements 
 under its sway, and is thus the intermediary of their 
 relations. The closer this dependence, the higher the 
 development of the nervous apparatus, and the better, 
 also, is assured the universal solidarity and therefore 
 the unity of the organism. Cellular federation 
 assumes the characteristic of a unique individuality 
 in proportion to the development of this nervous 
 centralization. With an ideal perfect nervous system 
 the correlation of the parts would also attain per- 
 fection. As Cuvier said : " None could experience 
 change without a change in the rest" 
 
 But no animal possesses this extreme solidarity of 
 the parts of the living economy. It is a philosopher's 
 dream. It is the dream of Kant, to whom the perfect 
 organism would be "a teleological system," a system 
 of reciprocal ends and means, a sum total of parts 
 each existing for and by the rest, for and by the 
 whole. An organism so completely connected would 
 be unlikely to live. In fact, living organisms show a
 
 320 LIFE AND DEATH. 
 
 little more freedom in the interplay of their parts. 
 Their nervous apparatus fortunately does not attain 
 this imaginary perfection ; their unity is not so 
 rigorous. The idea of individuality, of individual 
 existence, is therefore not absolute but relative. 
 There are all degrees of it according to the develop- 
 ment of the nervous system. What the man in the 
 street and the doctor himself understand by death is 
 the situation created by the stopping of the general 
 wheels, the brain, the heart, and the lungs. If the 
 breath leaves no trace on the glass held to the mouth, 
 if the beating of the heart is no longer perceptible by 
 the hand which touches or the ear which listens, if the 
 movement and the reaction of sensitiveness have 
 ceased to be manifest, these signs make us conclude 
 that it is death. But this conclusion, as we have said 
 before, is a prognostic rather than a judgment of fact. 
 It expresses the belief that the subject will certainly 
 die, and not that it is from this moment dead. To 
 the physiologist the subject is only on the way to die. 
 The process has started. The only real death is 
 when the universal death of all the elements has been 
 consummated.
 
 CHAPTER III. 
 
 PHYSICAL AND CHEMICAL CHARACTERS OF CEL- 
 LULAR DEATH. NECROBIOSIS. GROWING OLD. 
 
 Characteristic of elementary life Changes produced by death 
 in the composition and the death of the cell Schlemm ; 
 Loew ; Bokorny ; Pfliiger ; A. Gautier ; Duclaux The 
 processive character of death Accidental death Xecro- 
 biosis Atrophy Degeneration So-called natural death- 
 Senescence MetchnikofFs theory of senescence Objec- 
 tions. 
 
 ELEMENTARY death is nothing but the suppression 
 in the anatomical elements of all the phenomena of 
 vitality. 
 
 CJiariicteristics of Elementary Life. The char- 
 acteristic features of elementary life have been 
 sufficiently fixed by science. First of all, there is 
 morphological unity. All the living elements have an 
 identical morphological composition. That is to say 
 that life is only accomplished and sustained in all its 
 fulness in organic units possessing the anatomical 
 constitution of the cell, with its cytoplasm and its 
 nucleus, constituted on the classical type. In the 
 second place, there is chemical unity. The constituent 
 matter, the matter of which the cell is built up, diverges 
 but little from a chemical type a proteid complex, 
 with a hexonic nucleus, and from a physical model 
 which is an emulsion of granulous, immiscible liquids, 
 of different viscosities. The third character consists in 
 321
 
 322 LIFE AND DEATH. 
 
 the possession of a specific form acquired, preserved, 
 and repaired by the element. The fourth character, 
 and perhaps the most essential of all, is the property 
 of growth or nutrition with its consequence, namely, a 
 relation of exchanges with the external medium, 
 exchanges in which oxygen plays considerable part. 
 Finally, there is a last property, that of reproduction, 
 which in a certain measure is a necessary consequence 
 of the preceding, i.e., of growth. 
 
 These five vital characters of the elements are most 
 in evidence in cells living in isolation, in microscopical 
 beings formed of a single cell, protophytes and 
 protozoa. But we find them also in the associations 
 formed by the cells among one another i.e., in 
 ordinary plants and animals, multicellular complexes, 
 called for this reason metaphytes and metazoa. Free 
 or associated, the anatomical elements behave in the 
 same way feed, grow, breathe, digest in the same 
 manner. As a matter of fact, the grouping of the 
 cells, the relations, proximity and contiguity, which 
 they assume, introduce some variants into the ex- 
 pression of the common phenomena ; but these slight 
 differences cannot disguise the essential community 
 of the vital processes. 
 
 The majority of physiologists, following Claude 
 Bernard, admit as valent and convincing the proof that 
 the illustrious experimenter furnished of this unity 
 of the vital processes. There are, however, a few 
 voices crying in the wilderness. M. Le Dantec is one. 
 In his new theory of life he amplifies and exalts the 
 differences which exist between the elementary life of 
 the proteids and the associated life of the metazoa. 
 In them he can see nothing but contrasts and 
 deviations.
 
 PHYSICAL AND CHEMICAL CHARACTERS. 323 
 
 If this is elementary life, let us ask what is 
 elementary death />., the death of the cell. And in 
 this connection let us ask the questions which we have 
 to examine in the case of animals high in organiza- 
 tion, and of man himself. What are the characteristics 
 of elementary death ? When the cell dies, is its death 
 preceded by a growing old or senescence ? What are 
 the preliminary signs and the acknowledged symptons ? 
 
 Ctianges Produced by Death. The state of death is 
 only truly realized when the fundamental properties 
 of living matter enumerated above have entirely 
 disappeared. We must follow step by step this dis- 
 appearance in all the anatomical elements of the 
 metazoan. 
 
 Now the properties of the cell are connected with 
 the physical and chemical organization of living 
 matter. For them to disappear entirely, this organ- 
 ization must be destroyed as far as all that is essential 
 in it is concerned. We cannot admit with the 
 vitalists that there is any material difference between 
 the dead and the living, and that only an immaterial 
 principle which has escaped into the air distinguishes 
 the corpse from the animated being. In fact, the 
 external configuration may be almost preserved, and 
 the corpse may bear the aspect and the forms of the 
 preceding state. But this appearance is deceptive. 
 Something in reality has changed. The structure, 
 the chemical composition of the living substance, 
 have undergone essential changes. What are these 
 changes ? 
 
 Physical Clianges. Certain physiologists have 
 endeavoured to determine them. Klemm, a botanist, 
 pointed out in 1895 the physical changes which 
 characterize the death of vegetable cells loss of
 
 324 LIFE AND DEATH. 
 
 turgescence, fragmentation of the protoplasm, the 
 formation of granules, and the appearance of vacuoles. 
 
 Chemical Changes. O. Loew and Bokorny laid 
 great stress in 1886 and 1896 on the chemical changes. 
 The living protoplasm according to them is an 
 unstable proteid compound. A slight change would 
 detach from the albuminoid molecule a nucleus with 
 the function of aldehyde, and at the same time would 
 transform an amido-group into an amido-group. This 
 would suffice for the transition of the protoplasm from 
 the living to the dead state. This theory is based on 
 the fact that the compounds which exercise a toxic 
 action on the living cell, without acting chemically on 
 the dead albumin, are easily fixed by the aldehydes ; 
 and on the fact that many of them, which attack 
 simultaneously the living albuminoids and the dead 
 albumin, easily combine with the amido-group. 
 
 E. Pfliiger, a celebrated German scientist, has 
 considered living matter as an albumin spontaneously 
 decomposable, the essential nucleus of which is formed 
 by cyanogen. Its active instability would be due to 
 the penetration into the molecule of the oxygen which 
 fixes on the carbon and separates it from the nitrogen. 
 Armand Gautier has not confirmed this view. 
 Duclaux (1898) has stated that the difference between 
 the living and the dead albumin would be of a stereo- 
 chemical order. 
 
 Progressive Character of Death. Accidental Death. 
 We have seen that in general the disappearance of 
 the characteristics of vitality is not instantaneous, at 
 least in the natural course of things, in complex organ- 
 isms. It is the end of a more or less rapid process. But 
 death is not instantaneous in the isolated anatomical 
 element any more than it is in the protozoan or
 
 PHYSICAL AXD CHEMICAL CHARACTERS. 325 
 
 protophyte. We most have recourse to very violent 
 devices of destruction to kill the cell at a blow, to 
 leave absolutely nothing of its organization existing. 
 The protoplasm of yeast when violently crushed by 
 Biichner still possessed the power of secreting soluble 
 ferments. A powerful action, a very high temper- 
 ature, is necessary to obtain the result. A fortidri, 
 the difficulty increases in the case of complex organ- 
 isms, all of whose living elements cannot be attacked 
 at the same moment by the destructive cause. A 
 mechanical action, capable of destroying at one blow 
 all the living parts of a complex being, of an animal, 
 of a plant, must be of almost inconceivable power. 
 The blow of a Xasmyth hammer would not be strong 
 enough. 
 
 The chemical alteration produced by a very toxic 
 substance distributed throughout the blood, and thus 
 brought into contact with each element, would produce 
 a disorganization which, however rapid it were, could 
 not be called instantaneous. And the same holds 
 good of physical agents. 
 
 But these are not the processes of nature under 
 normal circumstances. They are accidents or devices. 
 We shall leave on one side their consideration and 
 we shall only deal here with the natural processes of 
 the organism. 
 
 Imagine it placed in a medium appropriate to its 
 needs and following out without intervening com- 
 plications the evolution assigned to it by its 
 constitution. Experiment tells us that this natural 
 evolution in every case known to us ends in death. 
 Death supervenes sooner or later. For beings higher 
 in organization, which we can bring into closer and 
 closer resemblance to man, we find that they die of
 
 326 LIFE AND DEATH. 
 
 disease, by accident, or of old age. And as disease 
 is an accident, we may naturally ask if what we call 
 old age is not also a disease. 
 
 However that may be, the mortal process, being 
 never instantaneous, has a duration, a beginning, a 
 development, an end in a word, a history. It 
 constitutes an intermediary phase between perfect 
 life and certain death. 
 
 Necrobiosis. Atrophy. Degeneration. The process 
 according to the circumstances may be shortened or 
 prolonged. When death is the result of violence 
 events are precipitated. The physical and chemical 
 transformations of the living matter constitute a kind 
 of acute alteration called by Schultze and Virchow 
 necrobiosis. According to the pathologists, there are 
 two kinds of necrobiosis : that by destruction, by 
 simple atrophy, which causes the anatomical elements 
 to disappear gradually without undergoing appreci- 
 able modifications ; and necrobiosis by degeneration, 
 which transforms the protoplasm into fatty matter 
 into calcareous matter, into granulations (fatty de- 
 generation, calcification, granulous degeneration). 
 There is no disagreement as to the causes of this 
 necrobiosis. They are always accidental ; they 
 originate in external circumstances: the insufficiency 
 of the alimentary materials, of water, of oxygen ; the 
 presence in the medium of real poisons destroying 
 the organized matter ; the violent intervention of 
 physical agents, heat, electricity ; the reflex on the 
 composition of the cellular atmosphere of a violent 
 attack on some essential organ, the heart, the lungs, 
 the kidneys. 
 
 Senescence. Old Age. In a second category we 
 must place the mortal processes, slow in their move-
 
 PHYSICAL AND CHEMICAL CHARACTERS. 327 
 
 ment, in which we cannot see the intervention of 
 clearly accidental and abnormal disturbing agents. 
 Death appears to be the termination of a breaking-up 
 proceeding by insensible degrees in consequence of the 
 progressive accumulation of very small inappreciable 
 perturbations. This slow breaking up is adequately 
 expressed by the term growing old, or senescence. 
 The alterations by which it is betrayed in the cell are 
 especially atropJiic, but they are also accompanied, 
 however, by different forms of degeneration. An 
 extremely important question arises on this subject, 
 and that is whether the phenomena of senility have 
 their cause in the cell itself, if they are inevitably 
 found in its organization, and therefore if old age and 
 death are natural and necessary phenomena. Or, on 
 the other hand, should we consider them as due to a 
 progressive alteration of the medium, the character of 
 which would be accidental although frequent or 
 habitual ? This, in a word, is the problem which has 
 so often engaged the attention of philosophical 
 biologists. Are old age and death natural and 
 inevitable phenomena ? 
 
 The recent experiments of Loeb and Calkins, and 
 all similar observations, tend to attribute to the 
 phenomenon of growing old the character of a 
 remediable accident. But the remedy has not been 
 found, and the animal finally succumbs to these slow 
 transformations of its anatomical elements. We then 
 say that it dies of old age. 
 
 Metchnikojfs Theory of Senescence. Objections. 
 Metchnikoff has proposed a theory of the mechanism 
 of this general senescence. The elements of the 
 conjunctive tissue, phagocytes, macrophages, which 
 exist every \vhere around the specialized and higher 
 
 22
 
 328 LIFE AND DEATH. 
 
 anatomical elements would destroy and devour them 
 as soon as their vitality diminishes, and would take 
 their place. In the brain, for example, it would be 
 the phagocytes which, attacking the nervous cellules, 
 would disorganize the higher elements, incapable of 
 defending themselves. This substitution of the con- 
 junctive tissue, which only possesses vegetative pro- 
 perties of a low order, for the nervous tissues, which 
 possesses very high vegetative properties, results in 
 an evident breaking-up. The gross element of 
 violent and energetic vitality stifles the refined and 
 higher element. 
 
 This expulsion is a very real fact. It constitutes 
 what is called senile sclerosis. But the active role 
 attributed to it by Metchnikoff in the process of 
 degeneration is not so certain. An expert observer 
 in the microscopic study of the nervous system, M. 
 Marinesco, does not accept this interpretation as far 
 as the senescence of the elements of the brain is con- 
 cerned. Diminution of the cell, the' decrease in the 
 number of its stainable granulations, chromatolysis, 
 the formation of inert, pigmented substances all 
 these phenomena which characterize the breaking-up 
 of the cerebral cells would be accomplished, according 
 to this observer, without the intervention of the 
 conjunctive elements, the phagocytes. 
 
 The characteristic of extensive and progressive 
 process presented by death necessitates in a com- 
 plex organism, which is a prey to it, the existence 
 side by side of living and dead cells. Similarly, in 
 the organism which is growing old, there are young 
 elements and elements of every age side by side with 
 senile elements. As long as the disorganization of 
 the last has not gone too far, they may be rejuvenated.
 
 PHYSICAL AND CHEMICAL CHARACTERS. 32Q 
 
 All we have to do is to restore to them an appropriate 
 ambient medium. The whole question is one of 
 knowing and being able to realize, for this or that 
 part which we wish to reanimate and to rejuvenate, 
 the very special or very delicate conditions that this 
 medium must fulfil. As we have said, success is 
 attained in this respect as far as the heart is con- 
 cerned, and this is why we are able to reanimate and 
 to revive the heart of a dead man. It is hoped that 
 ideas along these lines will extend with the progress 
 of physiology. 
 
 After this sketch of the conditions and of the 
 varieties of cellular death we must return to the 
 essential problem which is engaging the curiosity of 
 biologists and philosophers. Is death unavoidable, 
 inevitable? Is it the necessary consequence of life 
 itself, the inevitable issue, the inevitable end ? 
 
 There are two ways of endeavouring to solve this 
 question of the inevitability of death. The first is to 
 examine popular observation, practised, so to speak, 
 unintelligently and without special precautions. The 
 second is to analyze everything we know relative to 
 the conditions of elementary life.
 
 CHAPTER IV. 
 
 THE APPARENT PERENNITY OF COMPLEX 
 INDIVIDUALS. 
 
 Millenary trees Plants with a definite rhizome Vegetables 
 reproduced by cuttings Animal colonies Destruction due 
 to extrinsic causes Difficulty of interpretation. 
 
 POPULAR opinion teaches us that living beings have 
 only a transient existence, and as a poet has said : 
 " Life is but a flash between two dark nights." But, 
 on the other hand, simple observation shows us, or 
 appears to show us, beings whose duration of exist- 
 ence is far longer, and practically illimitable. 
 
 Millenary Trees. We know of trees of venerable 
 antiquity. Among these patriarchs of the vegetable 
 world there is a chestnut tree on Mount Etna which 
 is ten centuries old, and an ivy in Scotland which is 
 said to be thirty centuries old. Trees of 5000 years 
 old are not absolutely unknown. We may mention 
 among those of that age the famous dragon tree 1 at 
 Orotava, in the island of Teneriffe. Two other 
 examples are known in California the pseudo-cedar, 
 or Tascodiwn, at Sacramento, and a Sequoia gigantea. 
 We know that the olive tree may live 700 years. 
 There are cedars 800 years old and oaks of the age of 
 1,500 years. 
 
 Plants with a Rhizome. Vegetable species of 
 
 1 Lately destroyed in a storm. [Tr.] 
 330
 
 PERENNITY OF COMPLEX INDIVIDUALS. 33! 
 
 almost unlimited duration of life are known to 
 botanists. Such, for instance, are plants with a 
 definite rhizome, such as colchicum. Autumnal 
 colchicum has a subterranean root, the bulb of 
 which pushes out every year fresh axes for a new 
 bloom ; and as each of these new axes stretches out 
 an almost constant length, a botanist once set himself 
 the singular problem of discovering how long it would 
 take such a foot, if suitably directed, to travel round 
 the world. 
 
 Vegetables Reproduced by Cuttings. Vegetables re- 
 produced by slips furnish another example of living 
 beings of indefinite duration. The weeping willows 
 which adorn the banks of sheets of water in the parks 
 and gardens throughout the whole of Europe have 
 sprung, directly or indirectly, from slips of the first 
 Salix Babylonica introduced to the West May it not 
 be said that they are the permanent fragments of that 
 one and the same willow ? 
 
 Animal Colonies. These examples, as well as those 
 furnished to zoologists by the consideration of the 
 polypi which have produced by their slow growth the 
 reefs, or atolls, of the Polynesian seas, do not, how- 
 ever, prove the perennity of living beings. The 
 argument is valueless, for it is founded upon a con- 
 fusion. It turns on the difficulty that biologists 
 experience in defining the individual. The oak and 
 the polypus are not simple individuals, but associa- 
 tions of individuals, or, to use Hegel's expression, 
 the nations of which we see the successive genera- 
 tions. We give to this succession of generations a 
 unique existence, and our reasoning comes to this, 
 that we confer on each present citizen of this social 
 body the antiquity which belongs to the whole.
 
 332 LIFE AND DEATH. 
 
 Destruction of the Social Individual due to Extrinsic 
 Causes, As for the destruction, the death of this 
 social individual, of this hundred-year-old tree, it 
 seems indeed that there is no ground for considering 
 it a natural necessity. We find the sufficient reason 
 of its usual end in the repercussion on the individual 
 of external and contingent circumstances. The cause 
 of the death of a tree, of an oak many centuries old, 
 is to be found in the ambient conditions, and not in 
 some internal condition. Cold and heat, damp and 
 dryness, the weight of the snow, the mechanical 
 action of the rain, of hail, of winds unchained, of 
 lightning; the ravages of insects and parasites 
 these are what really work its ruin. And further, 
 the new branches, appearing every year and increas- 
 ing the load the trunk has to bear, increase the 
 pressure of the parts, and make more difficult the 
 motion of the sap. But for these obstacles, external, 
 so to speak, to the vegetable being itself, it would 
 continue indefinitely to bloom, to fructify, and as 
 each spring returned to show fresh buds. 
 
 Difficulty of Interpretation. In this as in all other 
 examples we must know the nature of the beings that 
 we see lasting on and braving the centuries. Is it the 
 individual? Is it the species? Is it a living being, 
 properly so called, having its unity and its in- 
 dividuality, or is it a series of generations succeeding 
 one another in time and extending in space? In a 
 word, the question is one of knowing if we have to do 
 with a real tree or with a genealogical tree. We are 
 just as uncertain when we deal with animals. What 
 is the being that lasts on a series of generations or 
 an individual? This doubt forbids us to draw any 
 conclusion from the observation of complex beings.
 
 PERENNITY OF COMPLEX INDIVIDUALS. 333 
 
 We must therefore return from them to the elementary 
 being, and we must examine it from the point of view 
 of perennity or of vital decay. Let us then ask the 
 questions that we have already examined with refer- 
 ence to animals high in organization and to man 
 himself. Is the death of the cell an inevitable char- 
 acteristic? Are there any cells, protophytes, protozoa, 
 which are immortal ?
 
 CHAPTER V. 
 
 THE IMMORTALITY OF THE PROTOZOA. 
 
 Impossibility of life without evolution Law of increase and 
 division Immortality of the protozoa Death, a pheno- 
 menon of adaptation which has appeared in the course of 
 the ages The infusoria The death of the infusoria Two 
 kinds of reproduction The caryogamic rejuvenescence of 
 Maupas Calkins on rejuvenescence Causes of senescence 
 Impossibility of life without evolution. 
 
 WE take into account, a priori, the conditions that 
 must be fulfilled by the monocellular being in order 
 to escape the inevitability of evolution, of the succes- 
 sion of ages, of old age, and of death. It must be 
 able indefinitely to maintain itself in a normal regime, 
 without changing, without increasing, maintaining its 
 constant morphological and chemical composition, in 
 an environment vast enough for it to be unaltered by 
 the borrowings or the spendings resulting from its 
 nutrition i.e., it must remain constant in the presence 
 of the constant being. We might conceive of a 
 nutrition perfect enough, of exchanges exact enough, 
 and regular enough, for the state of things to be 
 indefinitely maintained. This would be absolute 
 permanence realized in the vital mobility. 
 
 The Law of Growth and Division. This model of 
 a perfect and invariable machine does not exist in 
 nature. Life is incompatible with the absolute per- 
 334
 
 THE IMMORTALITY OF THE PROTOZOA. 335 
 
 manence of the dimensions and the forms of the living 
 organism. 
 
 In a word, it is a rigorous law of living nature that 
 the cell can neither live indefinitely without growth, 
 nor grow indefinitely without division. 
 
 Why is this so? Why is there this impossibility 
 of a regular regime in which the cell would be main- 
 tained in magnitude without diminution or increase? 
 Why has nutrition as a necessary consequence the 
 growth of the element? This is what we do not 
 positively know. 
 
 Things are so. It is an irreducible fact, peculiar to 
 the protoplasm, a characteristic of the living matter 
 of the cell. It is the fundamental basis of the pro- 
 perty of generation. That is all we can say about it. 
 Real living beings have therefore inevitably an evolu- 
 tion. They are not unchangeable. In its simple form 
 this evolution consists in the fact that the cell grows, 
 divides, and diminishes by this division, begins the 
 upward march which ends in a new division. And 
 so on. 
 
 Immortality of the Protozoa. It may happen, and 
 it does happen in fact, that this series of acts is 
 repeated indefinitely at any rate unless an accidental 
 cause should interrupt it The animal thus describes 
 an indefinite curve, constituted by a series of indenta- 
 tions, the highest point of which corresponds to the 
 maximum of size, and the lowest point to the 
 diminution which succeeds the division. This state of 
 things has no inevitable end if the medium does not 
 change. The being is immortal. 
 
 In fact, the compound beings of a single cell, proto- 
 phytes and protozoa, the algae and the unicellular 
 mushrooms, at the minimum stage of differentiation,
 
 336 LIFE AND DEATH. 
 
 escape the necessity of death. They have not, as 
 Weismann remarks, the real immortality of the gods 
 of mythology, who were invulnerable. On the con- 
 trary, they are infinitely vulnerable, fragile, and 
 perishable; myriads die every moment. But their 
 death is not inevitable. They succumb to accidents, 
 never to old age. 
 
 Imagine one of these beings placed in a culture 
 medium favourable to the full exercise of its activities, 
 and, moreover, wide enough in its extent to be un- 
 affected by the infinitely small quantities of material 
 which the animal may take from it or expel into it. 
 Suppose, for example, it is an infusorian in an ocean. 
 In this invariable medium the being lives, increases, 
 and grows continually. When it has reached the 
 limits of a size fixed by its specific law, it divides into 
 two parts, which are indistinguishable the one from 
 the other. It leaves one of its halves to colonize in its 
 neighbourhood, and it begins its evolution as before. 
 There is no reason why the fact should not be re- 
 peated indefinitely, since nothing is changed, either 
 in the medium or in the animal. 
 
 To sum up. The phenomena which take place in 
 the cell of the protozoan do not behave as a cause of 
 check. The medium allows the organism to revictual 
 and to discharge itself in such a way and with such 
 perfection that the animal is always living in a regular 
 regime, and, with the exception of its growth and 
 later on of its division, there is nothing changed 
 in it. 
 
 Death a Phenomenon of Adaptation It appeared in 
 the Course of the Ages. This immortality belongs in 
 principle to all the protista which are reproduced by 
 simple and equal division. If it be remarked that
 
 THE IMMORTALITY OF THE PROTOZOA. 337 
 
 these rudimentary organisms endowed with perennity 
 are the first living forms which have shown them- 
 selves on the surface of the globe, and that the}- have 
 no doubt preceded many others the multicellular, 
 for instance, which are liable, on the contrary, to 
 decay the conclusion is obvious: Life has long 
 existed without death. Death has been a pheno- 
 menon of adaptation which has appeared in the 
 course of the ages in consequence of the evolution of 
 species. 
 
 The Death of Infusoria. We may ask ourselves at 
 what moment in the history of the globe, at what 
 period of the evolution of its fauna, this novelty, 
 death, made its appearance. The celebrated experi- 
 ments of Maupas on the senescence of the infusoria 
 seem to authorize us to give a precise answer to this 
 question. By means of these experiments we are 
 led to believe that death must have appeared 
 at the same time as sexual reproduction. Death 
 became possible when this process of generation 
 was established, not in all its plenitude, but in its 
 humblest beginnings, under the rudimentary forms 
 of unequal division and of conjugation. This 
 happened when the infusoria began to people the 
 waters. 
 
 The Two Modes of Multiplication. Infusoria are, in 
 fact, capable of multiplication by simple division. 
 It is true to say that in addition to this resource, the 
 only one which interests us here, because it is the 
 only one which confers immortality, they possess 
 another. They present and exercise under certain 
 circumstances a second mode of reproduction, caryo- 
 gamic conjugation. It is a rather complicated 
 process in its detail, but it is definitively summed up
 
 33^ LIFE AND DEATH. 
 
 as the temporary pairing of two individuals, which 
 are otherwise very much alike, and which cannot be 
 distinguished as male and female. They become 
 closely united on one of their faces; they reciprocally 
 exchange a semi-nucleus which passes into the con- 
 joint individual; and then they separate. But 
 infusoria can be prevented from this conjunction by 
 regularly isolating them immediately after their birth. 
 Then they grow, and are constrained after a lapse of 
 time to divide according to the first method. 
 
 Maupas has shown that the infusoria could not 
 accommodate themselves to this regime indefinitely ; 
 they couIS not go on dividing for ever. After a 
 certain number of divisions they show signs of 
 degeneration and of evident decay. The size 
 diminishes, the nuclear organs become atrophied, 
 all the activities fail, and the infusorian perishes. 
 It succumbs to this kind of senile atrophy unless it 
 is given an opportunity of conjugation with another 
 infusorian in the same plight. In this act it then 
 derives new strength, it grows larger, attains its 
 proper size, and builds up its organs once more. 
 Conjugation gives it life, youth, and immortality. 
 
 A limentary Rejuvenescence. Recent observations 
 due to Mr. G. N. Calkins, an American biologist, 
 and confirmed by other investigators, have shown 
 that this method of rejuvenescence is not the only 
 one, and is not even the most efficacious. Conju- 
 gation has no mysterious, specific virtue. The 
 infusoria need not be married in order to be 
 rejuvenated. It is sufficient to improve their food. 
 In the case of the " tailed " paramecium we may 
 substitute beef broth and phosphates for conjuga- 
 tion. Calkins observed 665 consecutive generations
 
 THE IMMORTALITY OF THE PROTOZOA. 339 
 
 without blemish, without exhaustion, and without 
 any sign of old age. Plenty of food and simple 
 drugs have successfully resisted senility and the 
 train of atrophic degenerations which it involves. 
 
 Causes of Senescence, As for the causes of senes- 
 cence which have been remedied with such success, 
 they are not exactly known. Calkins thinks that 
 senescence results from the progressive losses to the 
 organism of some substance essential to life. Con- 
 jugation or intensive alimentation would act by build- 
 ing up again this necessary compound. G. Loisel 
 believes on the contrary that it is a matter of the 
 progressive accumulation of toxic products due to a 
 kind of alimentary auto-intoxication.
 
 CHAPTER VI. 
 
 LETHALITY OF THE METAZOA AND OF 
 DIFFERENTIATED CELLS. 
 
 Evolution and death of metazoa. Possible rejuvenescence of 
 the differentiated cells by the conditions of the medium. 
 Conditions of the medium for immortal cells. The 
 immortal elements of metazoa. The element in accidental 
 and remediable death. Somatic cells and sexual cells. 
 
 Evolution and Death of Metazoa. We have seen 
 that the infusoria are no longer animals in which 
 material exchanges take place with sufficient perfec- 
 tion, and in which cellular division, the consequence 
 of growth, is produced with sufficient precision and 
 equality for life to be carried on indefinitely in 
 a perfect equilibrium in the appropriate medium 
 without alteration or check. A fortiori we no 
 longer find the perfect regularity of nutritive 
 exchange in the classes above them. In a word, 
 starting from this inferior group, th'ere are no 
 animated beings in the state of existence which 
 Le Dantec calls " condition i " of manifested life ? " 
 Living matter, instead of being continually kept 
 identical in conditions of identical media, is modified 
 in the course of existence. It becomes dependent on 
 time. It describes a declining trajectory; it ex- 
 periences evolution, decay, and death* Thus the 
 340
 
 LETHALITY OF THE METAZOA. 34! 
 
 fundamental condition of invariable youth and 
 of immortality fails in all metazoa. The vital 
 wastes accumulate in all through the insufnciency 
 or the imperfection of nutritive absorption or of 
 excretion. Life decays ; the organism progressively 
 alters, and thus is constituted that state of de- 
 crepitude by atrophy or chemical modification 
 which we call senescence, and which ends in death. 
 To sum up, old age and death may be attributed to 
 cellular differentiation. 
 
 Possible Alimentary Rejuvenescence of the Differ- 
 entiated Cells Conditions of Medium. We must add, 
 however as the teaching of experiments in general 
 and in particular as the teaching of the experiments 
 of Loeb and of Calkins that a slight change of the 
 environment, made at the right time, is capable of 
 re-establishing equilibrium and of completely re- 
 juvenating the infusorian. Senescence has not in 
 this case a definitive any more than an intrinsic 
 character; a modification in the composition of the 
 alimentary medium will successfully resist it. If we 
 are allowed to generalize this result, it may be said 
 that senescence, the declining trajectory, the evolu- 
 tion step- by step down to death, are not for the 
 cells considered in isolation an inevitable and essen- 
 tially inherent in the organism, and a rigorous con- 
 sequence of life itself They preserve an accidental 
 character. In senescence and death there is no 
 really natural, internal cause, inexorable, and irre- 
 mediable, as was claimed in the past by J. M tiller, 
 and more recently by Cohnheim in Germany and 
 Sedgwick Minot in America. 
 
 Conditions of the Medium for Immortal Cells. As 
 for the cells which are less differentiated, the proto-
 
 342 LIFE AND DEATH. 
 
 phytes and the protozoa situated one degree lower in 
 the scale than the infusoria, we must admit the 
 possibility of that perfect and continuous equilibrium 
 which would save them from senile decrepitude. 
 And it is quite understood that this privilege re- 
 mains subordinated to the perfect constancy of the 
 appropriate medium. If the latter changes, the 
 equilibrium is broken, the small insensible per- 
 turbations of nutrition accumulate, vital activity 
 decays, and in sole consequence of the imperfection 
 of the extrinsic conditions or of the medium, the 
 living being finds itself once more dragged down to 
 decay and to death. 
 
 Immortal Elements of the Mctazoa. All the pre- 
 ceding facts and considerations refer to isolated cells, 
 to monocellular beings. But, and this is what makes 
 these truths so interesting, they may be extended to 
 all cells grouped in collectivity i.e., to all the 
 animals and living beings that we know. In the 
 complicated edifice of the organism, the anatomical 
 elements, at any rate the least differentiated, would 
 have a continual brevet of immortality. Generally 
 speaking, this would be the case for the egg, for the 
 sexual elements, and perhaps, too, for the white 
 globules of the blood, the leucocytes. And, further, 
 around each of these elements must be realized the 
 invariably perfect medium which is the necessary 
 condition. This does not take place. 
 
 Elements in Accidental and Remediable Death. As 
 for the other elements, they are like the infusoria, 
 but without the resource of conjugation. The 
 ambient medium becomes exhausted and intoxicated 
 around each cell, in consequence of the accidents 
 which happen to the other cells. Each therefore
 
 LETHALITY OF THE METAZOA. 343 
 
 undergoes progressive decay, and finally they 
 perish the decay and destruction being perhaps 
 in principle accidental, but, in fact, they are the 
 rule. 
 
 The different anatomical elements of the organism 
 are more or less sensitive to those perturbations which 
 cause senescence, necrobiosis, and death. There are 
 some more fragile and more exposed. Some are 
 more resisting, and finally, there are some which 
 are really immortal. We have just said that the 
 sexual cell, the ovum, is one. It follows that the 
 metazoan, man for instance, cannot entirely die. 
 Let us consider one of these beings. Its ancestors, 
 so to speak, have not entirely disappeared ; each has 
 left the fertile egg, the surviving element from which 
 has issued the being of which we speak ; and when 
 it in its turn has developed, part of that ovum has 
 been placed in reserve for a new generation. The 
 death of the elements is not therefore universal. 
 The metazoan is divided from the beginning into 
 two parts. On the one hand are the cells destined 
 to form the body, somatic cells. They will die. On 
 the other hand are the reproductive, or germinal, or 
 sexual cells, capable of living indefinitely. 
 
 Somatic and Sexual Cells. In this sense we may 
 say with Weismann that there are two things in 
 the animal and in man the one mortal, the soma 
 the body, the other immortal, the gennen. These 
 germinal cells, as in the case of the protozoa we 
 mentioned above, possess a conditional immortality. 
 They are imperishable, but on the contrary-, are 
 fragile and vulnerable. Millions of ova are destroyed 
 and are disappearing every moment. They may die 
 by accident, but never of old age. 
 
 23
 
 344 LIFE AND DEATH. 
 
 We now understand that if the protistae are 
 immortal, it is because these living beings, reduced 
 to a single cell, accumulate in it the compound 
 characters of the somatic cell and germinal cell, 
 and enjoy the privilege \vhich is attached to the 
 latter.
 
 CHAPTER VIL 
 
 MAN. THE DfSTDJCT OF LIFE AXD THE IX5TIXCT 
 OF DEATH. 
 
 The miseries at bmnanity: i. Disease; :. OBd age. Old age 
 considered as a duonic disease Its occasional cause. 5. 
 
 The disharmonies of human nateie: 4- The instinct of life 
 
 MAX'S unhappy plight is the constant theme of 
 philosophies and religions. Without referring to its 
 moral basis, it has a physical basis due to four 
 causes the physical imperfection or disharmony of 
 nature, dkrena*, old age. and death or rather of 
 three, for what we call old age is perhaps a simple 
 <KjaBaaR- These are the great sorrows of man. the 
 sources of all his woes. Disease attacks him, old age 
 awaits him, and death must tear him from all the 
 ties which he has formed. All his pleasures are 
 poisoned by the certain knowledge that they last 
 but for a moment, that they are as precarious as his 
 health, his youth, and his hie itself. 
 
 DISEASE. 
 
 Disease, frequent, constant, and inevitable as it is, 
 
 is, however, nothing but a fact outside the natural 
 
 order. Its character is clearly accidental, and it 
 
 interrupts the normal cycle of evolution- Medical 
 
 545
 
 346 LIFE AND DEATH. 
 
 observation teaches us, on the other hand, that the 
 health of the body reacts on that of the mind; and 
 therefore man as a whole, moral and physical, is 
 affected by disease. Bacon described a diseased 
 body as a jailer to the soul, and the healthy body as 
 a host. Pascal recognized in diseases a principle of 
 error. " They spoil our judgment and our senses." 
 
 I am not expressing a chimerical hope when I 
 predict that science will conquer disease. Medicine 
 has at last issued from the contemplative attitude 
 of so many centuries ; it has engaged in the 
 struggle, and signs of victory are already appearing. 
 Disease is no longer the mysterious power which it 
 was impossible to escape. Pasteur gave to it a body. 
 The microbe can be caught. In the words of 
 Schopenhauer, an alteration of the atmosphere so 
 slight that it is impossible to detect it by chemical 
 analysis may bring on cholera, yellow fever, the 
 black plague, diseases which carry off thousands of 
 men; and a slightly greater alteration might endanger 
 all life. The at once mysterious and terrifying spec- 
 tacle of the cholera at Berlin in 1831 had such an 
 effect on the philosopher that he fled in terror to 
 Frankfort. It has been said that this was the origin 
 of his pessimism, and that but for this he would have 
 continued to teach idealistic philosophy in some 
 Prussian university. L. Hartmann, another cele- 
 brated leader of contemporary pessimism, has also 
 said that disease will always be beyond the resources 
 of medicine. Facts have given the lie to these 
 sombre prognostics. The microbic origin of most in- 
 fectious diseases has been recognized. The discovery 
 of attenuated poisons and serums has diminished 
 their gravity. An exact knowledge of methods of
 
 MAN. THE INSTINCT OF LIFE AND DEATH. 347 
 
 contagion has enabled us to erect against them im- 
 pregnable barriers. Cholera, yellow fever, the plague 
 knock in vain at our doors. Diphtheria, dreaded by 
 every mother, has partially lost its deadly character. 
 Puerperal fever and blindness of the new-born child 
 are tending to disappear. Legend tells us that 
 Buddha in his youth, frightened at the sight of a 
 sick man, expressed in his father's presence the wish 
 to be always in perfect health and sheltered from 
 disease. The King answered: "My son! you are 
 asking the impossible." But it is towards the 
 realization of this impossibility that we are on our 
 way. Science is repelling the attacks of disease. 
 
 2. OLD AGE. 
 
 Old age is another sorrow of humanity. The 
 stage of existence in which the strength grows less 
 and never grows greater, and in which a thousand 
 infirmities appear, is not, however, a stage universal 
 in animals. Most of them die without our perceiving 
 in them any apparent signs of senile weakness. On 
 the other hand, some vegetables exhibit these signs. 
 Some trees are old; but it is in birds and mammals 
 that this decay, with the train of evils which accom- 
 panies it, becomes a very marked phase of existence. 
 In man to debility is added a bodily shrinkage, grey 
 hairs, withered skin, and the wearing out and loss of 
 teeth. The exhausted and atrophied organism offers 
 a favourable field to all intercurrent diseases and to 
 every cause of destruction. It is this discrepitude 
 which makes old age so hateful. All desire to be 
 old, said Cicero; and when they are old, they say 
 that old age has come quicker than they expected.
 
 34^ LIFE AND DEATH. 
 
 La Bruyere expresses it in an apothegm, "We want 
 to grow old, and we fear old age." One would like 
 longevity without old age. 
 
 But can life be prolonged without senility diminish- 
 ing its value? Metchnikoff thinks it can. He 
 more or less clearly catches a glimpse of a normal 
 evolution of existence which would make it longer 
 and nevertheless exempt from senile decay. 
 
 It is remarkable that we have so few scientific data 
 on the old age of man, and we have still fewer on 
 that of animals. The biologist knows no more than 
 the layman. The old age of the dog is betrayed by 
 its gait. Its coat loses its lustre, just as in disease. 
 The hair whitens around the forehead and the 
 muzzle. The teeth grow blunt and drop out. The 
 character loses its gaiety and becomes gloomy; the 
 animal becomes indifferent. He ceases to bark, and 
 often becomes blind and deaf. 
 
 It is admitted that senile degeneration is due to an 
 alteration affecting most of the tissues. The cells, 
 the special anatomical elements of the liver, the 
 kidney, and the brain are reduced by atrophy and 
 degeneration. At the same time, the conjunctive 
 woof which serves them as a support develops, on 
 the contrary, at the expense in a measure of the 
 higher elements. For this reason the tissues harden. 
 We know that the flesh of old animals is tough. We 
 know in pathology that this is happening to the 
 tissues. It is due to growth, to injury to the 
 active and important elements, to the elements of 
 support of the organs. They form a tissue some- 
 times called packed tissue, to show its secondary role 
 with reference to the elements which are deposited 
 in it. This kind of degeneration of the organs is
 
 MAN. THE INSTINCT OF LIFE AND DEATH. 34Q 
 
 known as sclerosis It constitutes the charasteristic 
 lesion of a certain number of chronic diseases; and 
 these diseases are serious, for the stifling of the 
 characteristic elements by the less important ele- 
 ments of the conjunctive or packed tissue results in 
 the more or less complete reduction or suppression 
 of the function. 
 
 The blood vessels also undergo this transformation, 
 and what we may call universal trouble and danger 
 ensue. This sclerosis of the arteries, this arterio- 
 sclerosis, not only deprives the walls of the blood 
 vessels of the suppleness and elasticity which are 
 necessary for the proper irrigation of the organs, but 
 it makes them more fragile. Thus it becomes a 
 cause of hemorrhage, which is a very serious matter 
 as far as the brain and lungs are concerned. 
 
 It is remarkable that the alteration of the tissues 
 during old age should be exactly similar to this. 
 This is inferred from the few researches that have 
 been made on the subject from those of Demange 
 in 1886, of Merkel in i8qi, and finally from the 
 researches of Metchnikoff himself. It is a generalized 
 sclerosis. As its consequence we have the lowering 
 of the proper activity of the organs and the danger 
 of cerebral hemorrhage created by arterio-sclerosis. 
 The transformations of the tissues in old men are 
 therefore summed up in the atrophy of the important 
 and specific elements of the tissues, and their replace- 
 ment by the hypertrophied conjunctive tissue. This 
 sclerosis is comparable to that of chronic diseases; 
 it is a pathological condition. Thus old age, as we 
 understand it, is a chronic disease and not a normal 
 phase of the vital cycle. 
 
 On the other hand, if we ask ourselves what is the
 
 350 LIFE AND DEATH. 
 
 origin of the scleroses which engender chronic 
 diseases, we find that they are due to the action of 
 various poisons, among which syphilitic poison and 
 the immoderate use of alcohol take the first place. 
 These are also the usual causes of senile degenera- 
 tion. But there must be some other, some very 
 general cause to explain the universality of the 
 process of senescence. Metchnikoff thinks that he 
 has found this cause in the microbes which swarm in 
 man's digestive tube, particularly in the large in- 
 testine. Their number is enormous. Strassburger 
 has given an approximate calculation, but words fail 
 to express it. We have to imagine a figure followed 
 by fifteen zeros. This microbic flora is composed of 
 " bacilli " and of " cocci," and comprises a third of 
 the rejected matter. It produces slow poisons, 
 which, being at once reabsorbed, pass into the blood 
 and provoke the constant irritation from which 
 results arterio-sclerosis and the universal sclerosis 
 of old age. Instead of enjoying a healthy and 
 normal old age, in which the faculties of ripening 
 years are preserved, we drag out a diminished life, 
 a kind of chronic disease, which is ordinary old age. 
 This is due, according to Metchnikoff, to the para- 
 sitism and the symbiosis of microbic flora, lodged in 
 a part of the economy in which it finds all the con- 
 ditions favourable to its prolific expansion. Such is 
 the specious theory, held to the verge of intrepidity, 
 by which this investigator explains the misery of our 
 old age, and which inspires him with the idea of a 
 remedy. For his observations conclude with a 
 regime, a series of prescriptions by which the author 
 fancies that life may be lengthened and the evils of 
 old age swept from our path. The dangerous flora
 
 MAN. THE INSTINCT OF LIFE AND DEATH. 35! 
 
 must be transformed into a cultivated and selected 
 flora. Although the organ in question may be of 
 doubtful utility, and although its existence, the 
 legacy of atavic heredity, must be considered as a 
 disharmony of human nature, Metchnikoff does not 
 go so far as to propose that it should be cut away, 
 and that we should call in surgery to assist in making 
 mankind perfect! But the rational means he pro- 
 poses will be endorsed by the most judicious students 
 of hygiene; and their effect, if it not as wonderful 
 as one hopes for, cannot fail to ameliorate the 
 conditions of old age and make it more vigorous. 
 
 3. DISHARMONIES IN HUMAN NATURE. 
 
 Another misery in the condition of man is due to 
 the dissidencies of his nature that is to say, to his 
 physical imperfections and the discordancies which 
 exist between the physiological functions and the 
 instincts which should regulate them. 
 
 This discordance reigns throughout the physical 
 organism. The body of man is not the perfect 
 masterpiece it was once supposed to be. It is 
 encumbered with annoying inutilities, with rudi- 
 mentary organs that have neither role nor function, 
 unfinished sketches which nature has left in the 
 different parts of his body. Such are the lachrymal 
 caruncle, a vestige of the third eyebrow in mammals; 
 the extrinsic muscles of the ear; the pineal gland of 
 the brain, which is only the rudiment of an ancestral 
 organ; the third eye, or the Cyclopean eye of the 
 saurians. The list is interminable. Wiedersheim has 
 counted in man 107 of these abortive hereditary
 
 352 LIFE AND DEATH. 
 
 organs, the useless vestiges of organs useful to our 
 remote animal ancestors, atrophied in the course of 
 ages in consequence of modifications that have taken 
 place in the external medium. 
 
 These rudimentary organs are not only useless; 
 they are often positively harmful. 
 
 But the most serious discordance is that which 
 exists between the physiological functions and the 
 instincts which regulate them. In a well-regulated 
 organism slowly developed by adaptation the instincts 
 and the organs alike should be in relation with the 
 functions. All really natural acts are solicited by 
 an instinct, the satisfaction of which is at once a 
 need and a pleasure. The maternal instinct is 
 awakened at the proper moment in animals, and it 
 disappears as soon as the offspring requires no more 
 assistance. A craving for milk is shown in all new- 
 born children, and often disappears at an early age. 
 
 Nature has endowed man as well as the other 
 animals with peculiar instincts, destined to preside 
 over the different functions and to ensure their 
 accomplishment. And, at the same time, it has 
 enabled him in a measure to deceive those instincts 
 and to satisfy them by other means than the execu- 
 tion of the physiological acts with a view to which 
 they exist. Love and the instinct of reproduction 
 exist in man before the age of puberty. Canova felt 
 the spur of love at the age of five. Dante was in 
 love with Beatrice at nine; and Byron, then scarcely 
 seven, was already in love with Maria Duff. On the 
 other hand, puberty has no necessary relation to the 
 general maturity of the organism. 
 
 The family instinct is subject to the same aberra- 
 tions. Man limits the number of his children. The
 
 MAN. THE INSTINCT OF LIFE AND DEATH. 353 
 
 Turks of to-day follow the ancient Greeks in the 
 practice of abortion. Plato approved of the custom, 
 and Aristotle sanctioned its general prevalence. In 
 the province of Canton the Chinese of the agricul- 
 tural classes kill two-thirds of their girl children, 
 and the same is done at Tahiti. All these customs 
 co-exist with the perfect love and tender care of the 
 living children. 
 
 Because of these different discordancies the" physical 
 life of man is insufficiently regulated by nature. 
 Neither the physiological instinct, nor the family 
 instinct, nor the social instinct is, in general, suffi- 
 ciently imperative and precise. Hence, since the 
 internal impulse has not sufficient power, the neces- 
 sity arises for a rule of conduct exercising its influence 
 from without. Philosophies, religions, and legislation 
 have provided for this. They have regulated man's 
 hygiene and the carrying out of his different physio- 
 logical functions. Their control has, moreover, had 
 its hygienic side. The scientific hvgiene of to-day 
 has inherited their role. 
 
 The idea of the fundamental perversity of human 
 nature is born of our cognizance of its discordancies, 
 unduly amplified and exaggerated. Soul and body 
 have been considered as distinctly discordant and 
 hostile elements. The body, the shroud of the soul, 
 the temporary host, the prison, the present source of 
 miseries, has been subjected to every kind of mortifi- 
 cation. Asceticism has treated the body and all the 
 innate instincts as our mortal foes. 
 
 This suspicion, this depreciation of human nature 
 was the great error of the mystics. This view was 
 as fatal as the inverse view of pagan antiquity. 
 The model of the perfect life according to Greek
 
 354 LIFE AND DEATH. 
 
 philosophy is a life in conformity with nature. To 
 aim at the harmonious development of man was the 
 precept of the ancient Academy, formulated by Plato. 
 The Stoics and the Epicureans had adopted the same 
 principle. Physical nature is considered as good. 
 It gives us the type, the rule, and the measure. The 
 moral rule itself is exactly appropriate to the physical 
 nature. We may say that pagan morality was 
 hygiene, the hygiene of the soul and the body alike; 
 the mens sana in corpore sano gave individual and 
 social direction. The Rationalists, the philosophers 
 of the eighteenth century, such as Baron d'Holbach 
 and later W. Von Humboldt, Darwin, and Herbert 
 Spencer, have adopted analogous views. If these 
 views have been contested, it is because of the im- 
 perfections or aberrations of the natural instincts of 
 man. Also, if we wish to base individual family or 
 social morality on the natural instincts of man, it 
 must be specified that these instincts are to be 
 regularized. We must necessarily appeal from the 
 imperfect instincts of the present to the perfected 
 instincts of the future. Their perfection, moreover, 
 will only be a more exact approximation to the real 
 nature of man, and he, having avoided by the aid of 
 science the accidents which cause disease and senile 
 decrepitude, will enjoy a healthy youth and an ideal 
 old age. 
 
 The reason of the discrepancies between instinct 
 and function in man is given by the natural history 
 of his development. We know that man has within 
 him original sin his long atavism. He has sprung, 
 according to the transformists, from a simian stock. 
 lie is a cousin, the successful relation, of a type 
 of antinomorphic monkeys, the chimpanzees. He
 
 MAX. THE INSTINCT OF LIFE AND DEATH 355 
 
 has "arrived," they have remained undeveloped. 
 Probably he had a common ancestor with them, 
 some dryopithecan of an extinct species. From that 
 type sprang a new type already on the way to 
 progress, the Pithecanthropus erectus. Finally, the 
 anthropoid ancestor became one fine day the father 
 of a scion, clearly superior to himself, a miraculously 
 gifted being, man. Here, then, is no sign of the slow 
 evolution and gradual progress, which is the doc- 
 trine held at present by Transformists. The Dutch 
 botanist De Vries has shown us, in fact, that nature 
 does leap: naturafacit saltus. There would thus be 
 crises, as it were, in the life of species. At certain 
 critical epochs considerable differences of a specific 
 value appear in their offspring. It is at one of these 
 critical periods in the simian life that man has 
 appeared as the phenomenal child of an anthropoid. 
 He was born with a brain and an intellect superior 
 to those of his humble parents; and on the other 
 hand, he has inherited from them an organization 
 which is only inadequately adapted to the new con- 
 ditions of existence created by the development of 
 his sensitiveness and his brain power. This intellect 
 is not proportioned to his organization, which has 
 not developed at the same rate: it protests against 
 the discordances which adaptation has not yet had 
 time to efface. But it will efface them in the future. 
 
 ^THE INSTINCT OF LIFE AND THE INSTINCT 
 OF DEATH. 
 
 The greatest discrepancy of this kind is the 
 knowledge of inevitable death without the instinct 
 which makes it longed for.
 
 356 LIFE AND DEATH. 
 
 There are immortal animals. Man is not of the 
 number. He belongs, like all highly organized 
 beings, to the class of beings which have an end. 
 They die from accident or from disease. They 
 perish in the struggle with other animals, or with 
 microbes, or with external conditions. There are 
 certainly very few, if there are any, which die a 
 really natural death. And so it is with man. We 
 see old men gradually declining who appear to 
 doze gently off into the last sleep, and become 
 extinguished without disease, like a lamp whose oil 
 is exhausted. But this is in most cases only 
 apparently so. Besides the fact that the old age to 
 which they seemed to succumb is really a disease, 
 a generalized sclerosis, autopsy always reveals some 
 lesion more or less directly responsible for the fatal 
 issue. 
 
 Man, like all the higher animals, is therefore 
 subject to the law of lethality. But while animals 
 have no idea of death and are not tormented by the 
 sentiment of their inevitable end, man knows and 
 understands this destiny. He has with the animals 
 the instinct of self-preservation, the instinct of life, 
 and at the same time the knowledge and the fear of 
 death. This contradiction, this discordance, is one 
 of the sources of his woes. 
 
 Whether it be an accident or the regular term of 
 the normal cycle, death always comes too soon. It 
 surprises the man at a time when he has not yet 
 completed his physiological evolution ; hence the 
 aversion and the terror it inspires. "We cannot 
 fix our eyes on the sun or on death," said La Roche- 
 foucauld. The old man does not regard death with 
 less aversion than the young man. " He who is
 
 MAX. THE INSTINCT OF LIFE AND DEATH. 357 
 
 most like the dead dies with most regret." Man 
 knows that he is not getting his full measure. 
 
 Further, all the really natural acts are solicited 
 by an instinct, the satisfaction of which is a need 
 and a joy. The need of death should therefore 
 appear at the end of life, just as the need of sleep 
 appears at the end of the day. It would appear, no 
 doubt, if the normal cycle of existence were fulfilled, 
 and if the harmonious evolution were not always 
 interrupted by accident. Death would then be 
 welcomed and longed for. It would lose its horror. 
 The instinct of death would replace at the wished 
 for moment the instinct of life. Man would pass 
 from the banquet of life with no other desire. He 
 would die without regret, "being old and full of 
 days," according to the expression used in the Bible 
 in the case of Abraham, Isaac, and Jacob. No 
 doubt there are some analogies to this in the insects 
 which only assume the perfect form for the purpose 
 of procreation and immediately perish in their full 
 perfection. In these animals the approach of death 
 is blended with the intoxication of hymen. Thus 
 we see some of them, the ephemerae, lose at that 
 moment the instinct of life and the instinct of 
 self-preservation. They allow themselves to be 
 approached, taken, and seized, and make no effort 
 at flight. 
 
 But what is this full measure of life which is 
 imparted to us? Metchnikoff holds that the ages 
 attributed to several persons in the Bible are very 
 probable Abraham lived 175 years, Ishmael 137, 
 Joseph no, Moses 120. Buffon believed in the 
 existence of a ratio between the longevity of animals 
 and the duration of their growth. He fixed it at
 
 358 ' LIFE AND DEATH. 
 
 7 : i. The animal whose development lasts two years 
 would thus have 14 years of life. This law would 
 give us 140 years, but the figure is too high, and 
 Flourens has reduced the ratio to that of 5 : i, which 
 would still give us 120 years. Plato died in the act 
 of conversation at 81 ; Isocrates wrote his Pana- 
 thena'icus at 94; Gorgias died in the full possession 
 of his intellect at 107. 
 
 To reach the end of the promised longevity we 
 must neither count on the elixir of life nor on the 
 potable gold of the alchemists, nor on the stone of 
 immortality which did not prevent its inventor, 
 Paracelsus, from dying at the age of 58, nor on 
 transfusion, nor on Graham's celestial bed, nor on 
 King David's gerocomy, nor on any nostrum or 
 remedy. Contra vim mortis non est medicamen in 
 hortis, said the Salernian school. What Feuchter- 
 sleben said is most true, " The art of prolonging life 
 consists in not cutting it short," and it is a hygiene, 
 but a brilliant hygiene, such as that of which 
 Metchnikoff traces us the future lines, which will 
 realize the desires of nature. 
 
 And now shall we find that physiology has solved 
 the enigma proposed by the Sphinx, and that it has 
 answered these poignant questions: Whence do 
 we come ? whither do we go ? what is the end of 
 life ? The end of life is, to the physiologist as well 
 as to Herbert Spencer, the tendency towards an 
 existence as full and as long as possible, towards a 
 life in conformity with real nature freed from the 
 discordancies which still remain ; it is the accom- 
 plishment of the harmonious cycle of our normal 
 evolution. This ideal human nature, without dis- 
 cordancies, no longer vitiated as it is at present but
 
 MAN. THE INSTINCT OF LIFE AND DEATH. 359 
 
 improved, will be the work of time and science. 
 Realized at last it will serve as a solid basis for 
 individual, family, and social morality. Healthy 
 youth fit for action; prolonged, adult age, the 
 symbol of strength ; normal old age, wise in council, 
 these would have their natural places in harmonious 
 society. " Great actions," said one of old, " are not 
 achieved by exertions of strength, or speed, or agility, 
 but rather by the prudence, the authority, and the 
 judgment which are found in a higher degree in old 
 age." The old age of which Cicero here speaks is 
 the ideal old age, regular and normal, and not the 
 premature, deformed, incapable and egoistic old age 
 which results from a pathological condition. At the 
 end of this full life, the old man being full of days, 
 will crave for the eternal sleep and will resign 
 himself to it with joy. . . . 
 
 Death, then, " the last enemy that shall be 
 destroyed," to use the expression of St. Paul, will 
 yield to the power of science. Instead of being 
 " the king of terrors," it will become after a long 
 and healthy life, after a life exempt from morbid 
 accidents, a natural and longed for event, a satisfied 
 need. Then will be realized the wish of the 
 fabulist : 
 
 "I should like to leave life at this age, fust as one 
 leaves a banquet, thanking the host, and departing." 
 
 Has this physiological solution of the problem of 
 death the virtue attributed to it by Metchnikoff? 
 Is it as optimistic as he thinks it is ? The instinct 
 of death supervening at the end of a normal and 
 well-fHled cycle will no doubt facilitate to the aged 
 their departure on the great voyage. The wrench 
 
 24
 
 360 LIFE AND DEATH. 
 
 will no longer exist for the dead. Will it not exist 
 for those who are left behind? And since the 
 instinct of death can only exist about the time at 
 which death is expected, will the young man and 
 the man of ripened years look with less horror than 
 to-day at the law which cannot be escaped, when 
 they are in full possession of the instinct of life, 
 but warned of the inevitability of death ?
 
 INDEX OF AUTHORS 
 
 Bonasse, 75, 304-5 
 Bml&iJi, 12 
 
 derai, 257, 242 
 
 ffllMllll'lUjMftl, 149 
 
 Bondt, 257 
 
 Bnorzis, 2$2 
 
 ':: ::. : ::_ :~ : 
 :-:v :;,:.> 
 Bhidbe, 44 
 
 5 
 
 i, 5, 14 
 
 :-. : 
 161-2, 175 
 
 j Con5nrs,245, 246 
 CaSQeaet, 272 
 
 _ _ ^ ^ ^_ ^ ^ ^ Calkins, 327, 338 
 
 4$, 150-1, tyi, 190-2, 194, 197, CaBwert, 271 
 204, 213, 214-21$, 239 HI nag., GEmadQe, 20 
 
 .I,-:. -::.:-:::.... :;: 
 
 114,121 
 152, Cbafy. 237, 271 
 
 ?:.:-: -.!.: : :: :: :-- 
 ;: -M-. ::.-:::;::.-:; :;: 
 
 7 
 , i, 6, JO), 22.27-30, 35, 55, 
 
 ::.; :-: : :.j :::.-
 
 362 
 
 INDEX OF AUTHORS. 
 
 D'ALEMBERT, 20, 59 note, 90, 92 
 
 Gruber, 165, 206, 257 
 
 Dantec, Le, 48, 52, 55 note, no, 
 
 Guignard, 161 
 
 148, 173, 198, 201, 203, 213, 
 
 Guillaume, 237, 262, 264, 271, 277 
 
 216, 220, 223 et seq., 231, 246, 
 
 Guillemin, 237 
 
 261, 285, 296, 340 
 
 Guldberg, 83 
 
 D' Arson val, 126 
 
 
 Darwin, 3, 46, 167, 258, 354 
 
 HARBERMANN, 183 
 
 Dastre, A., 192, 198 note 
 
 Haeckel, 3, 46, 164, 167, 246, 
 
 Davy, Sir Humphry, 6l, 80 
 
 251 
 
 Dela fosse, 282 
 
 Hales, 43 
 
 Delage, 208 
 
 Haller, 27 
 
 Demange, 349 
 Democritus, 34, 146 
 
 Hamilton, Sir W. Rowan, 67 
 Hammarsten, 180 
 
 Descartes, 3, 9, 35, 37, 40, 73, 91, 
 
 Hartmann, 276, 346 
 
 98 
 
 .Harvey, 43, 160 
 
 Despretz, 126 
 
 Hauy, 282 
 
 Diderot, 245, 246 
 
 Hegel, 170, 331 
 
 Drechsel, 183 
 
 Heidenhain, 3, 29, 30-1 
 
 Dressel, 20 
 
 Heitzmann, 161 
 
 Dubois-Reymond, 44, 58 note, 253 
 
 Ilelmholtz, 44, 56, 58, 67, 90, 97, 
 
 Duclaux, 119, 137, 184, 324 
 
 99, 252 
 
 Dufour, 297 
 
 Helmont, van, 3, 21, 26, 33, 146, 
 
 Duguet, 264 
 
 250 
 
 Duhem, 62, 264, 265 
 
 Henninger, 302 
 
 Dulong, 126 
 
 Heraclitus, 34 
 
 Dumas, 115, 149, 151-2 
 
 Hertwig, 167 
 
 
 Hertz, 88 
 
 EPICURUS, 35, 146 
 
 Hess, 91, 98 
 
 Ehrlich, 176 
 
 Hippocrates, 146 
 
 Errera, 52, 193-4, 237, 153, 295, 
 
 Him, 126 
 
 302 ct set/. 
 
 His, 46 
 
 Euclid, v. 
 
 Hlasitwetz, 183 
 
 
 Holbach, d', 354 
 
 FAYE, 260 
 
 Hoogewerf, 303 
 
 Feuchterslehen, 358 
 
 Ilopkinson, 271 
 
 Flemming, 161 
 
 Humboldt, W. von, 354 
 
 Flourens, 20-1, 152, 208, 306, 358 
 
 
 Fouillee, 242 
 
 INGENHOUSZ, 115 
 
 Fromann, 161 
 
 Izolet, 247 
 
 Fuerth, 183 
 
 
 
 JOULE, 53 note, 90-1, 93, 133 ct 
 
 GALEN, 25, 55, 143 
 
 seq., 143, 152 
 
 Galeotti, 180 
 
 
 Galileo, 73, 91, 98, 197, 241, 260 
 
 KANT, 312, 319 
 
 Gardair, 19, 248 
 
 Kaup, 213 
 
 Gautier, A., 3, 32, 36, 39, 176, 
 
 Kaufmann, 126 
 
 2 33. 324 
 
 Kelvin, Lord, 63, 67, 90, 92, 
 
 Gernez, 237, 288, 295 et seq. 
 
 251-2, 264; and the idea of 
 
 Glisson, 27 
 
 energy, 66 
 
 Goethe, 170, 312 
 
 Kepler, 29, 241 
 
 Gouy, 266, 268 
 
 Klemm, 323 
 
 Grimaud, 19 
 
 Koelliker, 160
 
 INDEX OF AUTHORS. 
 
 363 
 
 Kossel, 174, 179, 130-1, \Tf>ctseq. 
 
 Mayer, R., 56, 58, 89, 90, 97 
 
 99, 
 
 Kuhne, 45 
 
 IOI 
 
 
 Kuhm, 216 
 
 Mering, von, 133, 136 
 
 
 Kuliabko, 23, 311 
 
 Metchnikoff, 327 et seq. 
 
 
 Kunstler, 157, 161-2, 175 
 
 Miescher, 174, 179 
 
 
 Kuppfer, 161 
 
 Milne-Edwards, 152, 195 
 
 
 
 Minot, 341 
 
 
 LAMMETTRIE, 147 
 
 Miura, 137 
 
 
 Lamarck, 46 
 
 Mori, 145 
 
 
 Lapparent, 284 
 
 Mliller, 20, 27, 341 
 
 
 Lapicque, 140, 145 
 
 Murato, 45 
 
 
 Langley, 216 
 
 
 
 Laplace, 43, 63, 126, 260 
 
 N AEG ELI, 1 68 
 
 
 Laulanie, 103 
 
 Need ham, 46 
 
 
 Laurie, 271 
 
 Newton, 58 note, 70, 90-1, 93 
 
 
 La Rochefoucauld, 356 
 
 Noorden, van, 129, 137, 140, 
 
 2IO 
 
 Lavoisier, 3, 28, 30, 36, 43, 65, 
 
 Nussbaum, 165, 206, 215, 217 
 
 
 117, 121, 126, 128, 143, 176, 
 
 
 
 296 
 
 OBERMEYER, 271 
 
 
 Lea, 216 
 
 Osmond, 237, 271 
 
 
 Le Chatelier, 85, 92 
 Lechatelier, H. and A., 271 
 
 Ostwald, 41, 62, 67, 85, 104, 
 258, 289, 295 et seq. 
 
 237, 
 
 Lecocq de Boisbaudran, 295 
 
 
 
 Leeuwenhoek, 232 
 
 PARACELSLS, 26, 146, 312 
 
 
 Lefevre, 126 
 
 Pascal, 74, 161 
 
 
 Legallois, 21 
 
 Pasteur, 53, 191,2224/0?., 
 
 237, 
 
 Ley-dig, 161-2 
 
 250, 288, 346 
 
 
 Liebermeister, 136 
 
 Payen, 151 
 
 
 Liebig, 26, 53 note, 117 
 
 Persoz, 152 
 
 
 Lilienfeld, 179, 247 
 
 Petit, I So 
 
 
 Locke, 23 
 
 Pettenkofer, 210 
 
 
 Lodge, 271 
 
 Pfeffer. 175, 193 
 
 
 Loeb, 43, 167, 327, 341 
 
 Pfluger, 12, 56, 135, 144, 176, 
 
 210, 
 
 Loew, 324 
 
 213 
 
 
 Loisel, 339, 341 
 
 Philpotts, 46 
 
 
 Lorry, 21 
 
 Pictet, 233 
 
 
 Longet, 52 
 
 Pitcairn, 35 
 
 
 Lowitz, 297 
 Loye, 192 
 
 Plato, 35, 307 
 Plosz, I 80 
 
 
 Ludwig, 44, 215 
 
 Poincare, 62 
 
 
 
 Poisson, 63 
 
 
 MACH, 41, 62 
 
 Preyer, 192, 252 el siq. 
 
 
 Magendie, 43, 143 
 
 Priestley, 115 
 
 
 Magy, 37 
 
 Ptolemy, v. 
 
 
 Malgaigne, 153 
 
 Pythagoras, 18 
 
 
 Mallard, 284 
 
 
 
 Marinesco, 231, 328 
 
 RAUBER, 237, 288 
 
 
 Markel, 349 
 
 Raulin, 191 
 
 
 Maspero, 3, 234 
 Matthiesson, 271 
 
 Regnault, 117 
 Reinke, 3, 32 
 
 
 Maupas, 337 
 Maxwell, 88 
 
 Renan, 240 
 Ribbert, 208 

 
 INDEX OF AUTHORS. 
 
 Ribot, 247 
 
 Swann, 159 
 
 Riche, 271 
 
 Swift, 262 
 
 Richet, 50, 126, 140 
 
 
 Richter, 252 
 
 TAIT, 53 note, 66 
 
 Rindfleisch, 4 
 
 Tammann, 237, 253, 295 et seq. 
 
 Roberts- Austen, 237, 271-2 
 
 Thales, 34 
 
 Robin, 62, 177 
 
 Thomson, Sir J. J., 279 
 
 Rosenthal, 126 
 
 Tissot, 12 
 
 Rouvier, 160 
 
 Tomlinson, 264 
 
 Roux, 46, 165 
 
 Trembley, 22, 206 
 
 Rubner, 129, 130, 140 et seq., 
 
 Tsuboi, 145 
 
 210 
 
 Tylor, 8 
 
 Rumford, 80 
 
 
 
 VERWORN, 206, 252, 257 
 
 SABATIER, 242 
 
 Violette, 295 
 
 Sachs, 161, 194 
 
 Virchow, 318, 326 
 
 Salles-Guyon, 252 
 Sanderson, Burdon, 176 
 
 Voit, 119, 1 33 et set/., 210 
 Vries, de, 46, 258, 355 
 
 Scaliger, 241 
 
 Vulpian, 24 
 
 Schleiden, 159 
 
 
 
 Schopenhauer, 346 
 
 WAAGE, 83 
 
 Schwartz, 162 
 
 Waller, 47, 206 
 
 Schultze, 1 60, 326 
 
 Wallerant, 282-3 
 
 Schultzenberger, 174, 162 et seq . 
 Secchi, 88 
 
 Warburg, 264 
 Watt, 76 
 
 Seguin, 58 note, 90 
 
 Weismann, 46, 167, 336, 343 
 
 Senebier, 115 
 
 Wertheim, 264 
 
 Siven, 145 
 
 Whitman, 46 
 
 Spallanzani, 43, 233 
 
 Widersheim, 351 
 
 Spencer, Herbert, 46, 247, 454, 
 
 Wiedermann, 264 
 
 358 
 
 Wiesner, 167 
 
 Spring, 272 
 
 Willis, 36, 147 
 
 Stahl, 3, 9, 12, 35, 146 
 
 Winternitz, 126 
 
 Stammreich, 137 
 
 
 Stead, 237 
 
 YUNG, 233 
 
 Stohmann, 129, 130, 140 
 
 
 Strassburger, 161, 350 
 
 ZUNTZ, 133, 136, 210
 
 IXDEX OF SUBJECTS. 
 
 
 :,, 
 
 .- 
 
 : :,-. . 
 
 35 
 
 CAIOTE, 125 n&r 
 
 if 
 
 iSzrfJ*. 
 
 : :;:: ' : : 
 ,33.39,45 
 
 3% 9K; Ins of lio, 
 105 rf xy, 2x9; afi- 
 
 365
 
 366 
 
 INDEX OF SUBJECTS. 
 
 Energy, 37, Book ii., passim; 
 origin of idea of, 57 ; theory of, 
 62 ; the only objective reality, 
 64-5 ; and kinetic conception, 
 67 ; mechanical, 69, 73 ; of con- 
 traction, 75; kinetic, 76, 83; 
 potential, 76, 83; virtual, 77; 
 of motion and position, 79; 
 thermal, and its measurements, 
 80-2 ; chemical, and its measure- 
 ments, 81-2; chemical and po- 
 tential, 83; materialization of, 
 84 ; transformations of, 85 et seq. ; 
 luminous, 86 et seq. ; conserva- 
 tion of, 90 et seq.', capacity of 
 conversion of, 93 ; in biology, 
 97 ; in living beings, 99 et seq. ; 
 physical, 99 et seq.; vital, 99 
 et seq. 
 
 Ether, 89 
 
 Equivalence, law of, 91 
 
 Excitability, 26-7 
 
 FATIGUE, of metals, 264 
 Ferments, butylic and butyric, 
 
 193 
 
 Filiation, 250 
 Finulism 43 
 Food, a source of energy, 118 
 
 et seq. ; thermogenic and bio- 
 
 thermogenic types of, 131 et seq. ; 
 
 dynamogenic type of, 143; 
 
 nitrogenous, 143 ; of animals 
 
 and plants, 153 et seq. 
 Force, directive, 16 et seq., 32, 39, 
 
 48 ; vital, 45 ; an anthromorphic 
 
 notion, 71 ; and work, 74; 
 
 measurement of, 71 ; plastic, 
 
 143; plastic and morpho plastic 
 
 forces, 208 
 
 Form, specific, 199 et seq., 281 
 Fruits, acids of, 136 
 
 GEMMULES, 167, 258 
 Generation, spontaneous, 249 et 
 
 seq., 294 et seq. 
 Globulin, 178 
 Glyceriue, crystals of, 302 
 Glycogen, 108, 153 et seq. 
 Gramme, 71 
 
 HEAT, a mode of motion, 61 ; role 
 of animal heat, 122 ; mechanical 
 equivalent of, Si ; an excretum, 
 1 14 ; a degraded form of energy. 
 88; converted into work, 92 
 
 Heterogeneity, 38, 61 
 
 Histones, 179, 182 et seq. 
 
 Horse-power, 75 
 
 Hyaloplasm, 161 
 
 IATRO-CHEMISTRY and mechanics, 
 
 34-5 
 
 Idioblasts, 167 
 Infusoria, death of, 337 
 Instability, 188 et seq. 
 Instinct, of life and death, 345 
 
 et seq. 
 
 Intussusception, 291 
 Invariant, mass the first, 63 
 Irreversibility, of vital energies, 
 
 104 
 
 Irritability, 27, 196 et seq. 
 Isodynamism, 142 
 Isomorphism, 286 
 
 KA, the, 8 
 
 Kilogrammetre, 72, 75; per 
 
 second, 75 
 Kilowatt. 76 
 Kinetic theory, 39, 62 
 Knot, the vital, 21 
 
 LEUCIXES, 183 
 
 Leucites, 163 
 
 Life, defined, 28 ; latent, 233 ; 
 
 physico-chemical theory of, 36 ; 
 
 elementary, 321 
 163 
 
 MASS, and matter, 63 
 
 Materialism, 34 
 
 Matter, 37, 60, 62 ; and mass, 63 ; 
 two kinds of, 63; life of, 236 
 et seq. ; brute and living, 249 
 et seq. ; organization and con- 
 stitution of, 255 et seq. ; defined 
 as extension, 64 ; conservation 
 of, 65
 
 INDEX OF 5UBJECT5- 
 
 " Memory," of Kfiab, etc., 265 | 
 
 Merotomy, 47 
 Mecaboiism. 117 
 
 Metizoa, evolution and death oC. 
 340^^. 
 
 - . : - : 
 MicelLir theory, 166 X sef. 
 
 - : ; 
 
 - . :.'_.-: : - 
 ' . 
 
 -Vl'Xitiity of stars. 260 
 Modality, twofold, of soul, 12 
 Mokoles, o^nic, 254 
 Monism, 34, Chap. iv. passim, 63 
 ': - -. : -T -:- . :: 
 
 .MflOon, CJHC ot, 71 ; ^""^Ft^r coo- 
 
 - 
 
 : : : : n; - :-: 
 
 231 f jay. ; fcie ia crushed, 257 
 
 : - 
 
 70,75 
 
 Tital, 15 f jvy. 
 
 ;:.:.: 
 
 : 
 
 -srs^i?4^ s ^ == ^' ; 
 
 Mahflky, So, iSS rf ^:-! ; of 
 Uiing alter. 259 r ay. - of 
 
 CE, 305 rf *<y. 
 , in brace bodies, 
 
 Seaabuitr, 
 
 Solidarity, of aKtrowtical dements. 
 
 ocai znd nerrcos, 317 
 SoaJ, the, 7 r ay. 
 Space, 69 
 
 SpeciiicitT, itaI T ^S 
 * 
 
 XECKOMOSIS, 326 
 Neo-Tiiaiism. 15, 29, 32 
 Neility,27 
 Nickel, steels, 277 
 
 - 
 
 Novs, the, iS, 239 
 Xodems, 179, iSo it setf. 
 Nacko-albvMuaokis, 17$; -po- Scares, initial and deal, 12 
 
 tesds, 177 ft sty. Swdling, 167 
 
 N -: T--. : : : - . - - - _ - - _ . 
 
 Nutrition, directed, 305, 209 et 
 
 '--' - - ' ' \ TAGMATA, 169, 175 
 
 ' Teleology, 43 
 Tetanus, tiactera of r 03 
 
 0^<W^*< iieTof 1 *^ ^ 
 
 ot, 315 ; perfect, 319 
 
 Trees, and immortafity, 330 et sea. 
 PAXGKXFS, 167 
 252 
 
 r:ir--. ".I.-. -:::---;;
 
 368 
 
 INDEX OF SUBJECTS. 
 
 VACUOI.ES, 113 
 
 Vibrion, septic, 193 
 
 Vis viva, 73 
 
 Vital properties, theory of, 29 
 
 et seq. 
 Vitalism, 6, 7, Chap. iii. passim : 
 
 physico-chemical, 29 
 Vitality, phenomena of, 216 
 Vortex, vital, 105, I2O, 229 et seq. 
 Vulcans, 26-7 
 
 WEIGHT, energy of position, 64 ; 
 conservation of, 65 ; movement 
 under action of, 271 et seq. 
 
 Work, 70, 72 ; and force, 74, 77 ; 
 convened into heat, 92 ; physio- 
 logical, 103 
 
 XANTHIC bases, 180 
 i ZONES, mctastable and labile, 301 
 
 
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 11 
 
 OarneSTiL" 
 
 Life of Goethe. By James Si roe. 
 
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 Life of Victor Hugo. By Frank T. Marzials. 
 
 presents to us, in a more handy form than any 
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 Life of Hunt. By 
 
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 Life of Longfellow. By Prof. Eric S. Robertson. 
 
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 |> I. THE EVOLUTION OF SEX. By Prof. PATRICK GEDDES 
 
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 J* II. ELECTRICITY IN MODERN LIFE. By G. W. DE 
 'E Q TUNZELMANN. With 88 Illustrations. 
 
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 W 
 
 >. VII. THE CRIMINAL. By HAVELOCK ELLIS. Illustrated 
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 * 
 
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 -eB 1 aliciencr ! mWidrfi.ota^--/W?J&^Gk-fc 
 
 IX. HYPNOTISM. By DC ALBERT MOLL New and Enbiged 
 
 Edition. 
 " Maries a step of same inwntante io the stedr of nw dittos phnav 
 
 ' - _ .. _.._,.. 
 
 igiLjm ana jKyuBuiagicu promcm %Uauk nti.itc not y* iccovofl HCB ^ 
 
 -lcku,t J S ^fewcridcrfE. C lL--Ator. - 
 
 X. MANUAL TRAININa By Dr. C. M. WOODWARD, Dirertot 
 
 of tb Manual Training School, St. Loais. Illustrated. ~- 
 
 Xincfc 2s no siuicr **"f rt fT < fy OB tibc "nuliBUtt tituft PTOafessoc VToodwrdL -^ *~ 
 
 XL THE SCONCE OF FAIRY TALES. By E. SIDXKY 
 
 HARTLAXD. 
 "M. Haitbn^s book wffl via the 
 
 of hfes hjcd, which is erideat ihwaghuaL* -Sfrdmtir. '2 
 
 XIL PRIMITIVE FOLK. By ELIE Rectos. < 
 
 :: :'-.e r..:;. , ::,., .: 
 
 THE EVOLUTION OF MARRIAGE. By Professor 
 
 "Amo^thediuiBgaBhed French 
 ne has kng stood in 
 
 * tank. He appradxs the great study of 
 
 man &ee from bias and ^17 of genen&atians. To coded, scradnise, and 
 appraise fete is Ids chief bmsinesL In the volnroc bciore ns be shows thee 
 
 XIV. BACTERL\ AND THEIR PRODUCTS. By Dr. a 
 
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 -AneaaBeMflHHHnror the pRscnt state of kMiriedge of thesrf^cel." 
 
 
 XV. EDUCATION AND HEREDITY. By J. M. GUVAU. g z 
 "ft is at once a feolise on sodofagj, ethics, aad pedagogics. It is C ~ :z 
 
 --:-::., .-...-.--.: - 7- 
 
 ':: :V - : - - M'= - - : ' -- "---' : -- -^ - '- I -| 
 
 < -* 
 
 XVL THE MAN OF GENIUS. By Prot LOMBROSO. IDns- ? 
 
 > 
 
 New YoA : CHAEtJS Sc MBXUl'S SOKS.
 
 XVII. THE HISTORY OF THE EUROPEAN FAUNA. 
 By R. F. SCHARFF, B.Sc., Ph.D., F.Z.S. Illustrated. 
 
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 By CH. LETOURNEAU, General Secretary to the Anthro- 
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 pology, Paris. 
 
 " M. Letourneau has read a great deal, and he seems to us to have 
 selected and interpreted his facts with considerable judgment and learning." 
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 XIX. VOLCANOES, PAST AND PRESENT. By Prof. 
 EDWARD HULL, LL.D., F.R.S. 
 
 " A very readable account of the phenomena of volcanoes and earth- 
 quakes. " Nature. 
 
 XX. PUBLIC HEALTH. By Dr. J. F. J. SYKES. With 
 
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 XXI. MODERN METEOROLOGY. AN ACCOUNT OF THE 
 GROWTH AND PRESENT CONDITION OF SOME BRANCHES 
 OF METEOROLOGICAL SCIENCE. By FRANK WALDO, Ph.D., 
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 etc.; late Junior Professor, Signal Service, U.S.A. With 112 
 Illustrations. 
 
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 have seen." Daily Telegraph (London). 
 
 XXII. THE GERM-PLASM : A THEORY OF HEREDITY. 
 
 By AUGUST WEISMANN, Professor in the University of 
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 bearing on the subject." British Medical Journal. 
 
 XXIII. INDUSTRIES OF ANIMALS. By E. F. HOUSSAY. 
 With numerous Illustrations. 
 
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 New York : CHARLES SCRIBNER'S SONS.
 
 XXIV. MAN AND WOMAN. By HAVELOCK ELLIS. Illus- 
 trated. Fourth and Revised Edition. 
 
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 XXV. THE EVOLUTION OF MODERN CAPITALISM. 
 
 By JOHN A. HOBSON, M.A. (New and Revised Edition.) 
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 facts as conscientious as it is acute, a keen sense of the importance of certain 
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 [Mr. Hobson's] personal sympathies." Pall Mall Gazette. 
 
 XXVI. APPARITIONS AND THOUGHT - TRANSFER- 
 ENCE. By FRANK PODMORE, M.A. 
 
 "A very sober and interesting little book. . . . That thought-transfer- 
 ence is a real thing, though not perhaps a very common thing, he certainly 
 shows. " Spectator. 
 
 XXVII. AN INTRODUCTION TO COMPARATIVE 
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 Diagrams. 
 
 " A strong and complete exposition of Psychology, as it takes shape in a 
 mind previously informed with biological science. . . . Well written, ex- 
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 XXVIII. THE ORIGINS OF INVENTION : A STUDY OF 
 INDUSTRY AMONG PRIMITIVE PEOPLES. By OTIS T. MASON, 
 Curator of the Department of Ethnology in the United States 
 National Museum. 
 
 "A valuable history of the development of the inventive faculty." 
 Nature. 
 
 XXIX. THE GROWTH OF THE BRAIN: A STUDY OF 
 THE NERVOUS SYSTEM IN RELATION TO EDUCATION. By 
 HENRY HERBERT DONALDSON, Professor of Neurology in the 
 University of Chicago. 
 
 " We can say with confidence that Professor Donaldson has executed his 
 work with much care, judgment, and discrimination." The Lancet. 
 
 XXX. EVOLUTION IN ART: As ILLUSTRATED BY THE 
 LIFE-HISTORIES OF DESIGNS. By Professor ALFRED C. 
 HADDON. With 130 Illustrations. 
 
 "It is impossible to speak too highly of this most unassuming and 
 invaluable book." Journal of Anthropological Institute. 
 
 New York : CHARLES SCRIBNER'S SONS.
 
 XXXI. THE PSYCHOLOGY OF THE EMOTIONS. By 
 TH. RlBOT, Professor at the College of France, Editor of the 
 Revue Philosophique. 
 
 "Professor Ribot's treatment is careful, modern, and adequate." 
 Academy. 
 
 XXXII. HALLUCINATIONS AND ILLUSIONS: A STUDY 
 OF THE FALLACIES OF PERCEPTION. By EDMUND PARISH. 
 
 " This remarkable little volume." Daily News. 
 
 XXXIII. THE NEW PSYCHOLOGY. By E. W. SCRIPTURE, 
 Ph.D. (Leipzig). With 124 Illustrations. 
 
 XXXIV. SLEEP : ITS PHYSIOLOGY, PATHOLOGY, HYGIENE, AND 
 PSYCHOLOGY. BY MARIE DE MANACEINE (St. Petersburg). 
 Illustrated. 
 
 XXXV. THE NATURAL HISTORY OF DIGESTION. 
 By A. LOCKHART GILLESPIE, M.D., F.R.C.P. ED., F.R.S. 
 ED. With a large number of Illustrations and Diagrams. 
 
 " Dr. Gillespie's work is one that has been greatly needed. No com- 
 prehensive collation of this kind exists in recent English Literature." 
 American Journal of the Medical Sciences. 
 
 XXXVI. DEGENERACY : ITS CAUSES, SIGNS, AND RESULTS. 
 By Professor EUGENE S. TALBOT, M.D., Chicago. With 
 Illustrations. 
 
 "The author is bold, original, and suggestive, and his work is a con- 
 tribution of real and indeed great value, more so on the whole than anything 
 that has yet appeared in this country." American Journal of Psychology. 
 
 XXXVII. THE RACES OF MAN: A SKETCH OF ETHNO- 
 GRAPHY AND ANTHROPOLOGY. By J. DENIKER. With 178 
 Illustrations. 
 
 "Dr. Deniker has achieved a success which is well-nigh phenomenal." 
 British Medical Journal. 
 
 XXXVIII. THE PSYCHOLOGY OF RELIGION. AN 
 EMPIRICAL STUDY OF THE GROWTH OF RELIGIOUS CON- 
 SCIOUSNESS. By EDWIN DILLER STARBUCK Ph.D., Assistant 
 Professor of Education, Leland Stanford Junior University. 
 
 "No one interested in the study of religious life and experience can 
 afford to neglect this volume." Morning Herald. 
 
 XXXIX. THE CHILD : A STUDY IN THE EVOLUTION OF MAN. 
 By Dr. ALEXANDER FRANCIS CHAMBERLAIN, M.A., Ph.D., 
 Lecturer on Anthropology in Clark University, Worcester 
 (Mass.). With Illustrations. 
 
 "The work contains much curious information, and should be studied by 
 those who have to do with children." Sheffield Daily Telegraph. 
 
 New York : CHARLES SCRIBNER'S SONS.
 
 XL. THE MEDITERRANEAN RACE. By Professor SERGL 
 
 \\ ith over 100 Illustrations. 
 
 " M. Sergi has given m a hvad awl complete exposition of his views on a 
 abject of supreme interest/' Irish Trmus. 
 
 XLL THE STUDY OF RELIGION. By MORRIS JASIROW. 
 
 JUBL, PhJX, Professor in the University of Pennsylvania. 
 "This work presents a careful survey of the sabject, and forms mm 
 
 XLIL HISTORY OF GEOLOGY AND PALEONTOLOGY 
 TO THE END OF THE NINETEENTH CENTURY. 
 By KARL vox ZITTEL. 
 
 : It is a rery mastcriy liraihr, mutlat will a wide grasp of 
 " s. s Pmt&s&erf ( 
 
 XLJIL THE MAKING OF CITIZENS : A STUDY DC COM- 
 PARATIVE EDUCATION. By R. E. HUGHES, M_A. (Oxon.), 
 RSo Lend.). 
 
 "Mr. H^hes gives a l*dd acoonnt of the exact ] 
 England, Germany, Facce. and the United 
 present a dear and attractive picture of the manner in which one of the 
 greatest awabB BOW at kne kbemg soHed both at home and abroad. 1 " 
 StaM^rd. 
 
 XLJV. MORALS: A TREATISE ox THE PSYCHO-SOCIOLOGICAL 
 BASES OF ETHICS. By PROFESSOR G. L. DUPRAT. Trans- 
 lated by W. J. GREEXSTREET, M^, F.R-A.& 
 ' The present work is representatrrc of Ac modern departnre in the 
 treatment of the theory of morals. The aether brings a wide knowledge 
 to bear on his sabject. 1 * EimaHm. 
 
 XLV. A STUDY OF RECENT EARTHQUAKES. By 
 CHARLES DAVTSOX, D.Sc^ F.G.S. \\ ith liUrUiations. 
 " Dr. Danson has done his work wdL" WlntmnuUf GaatOe, 
 
 XLVI. MODERN ORGANIC CHEMISTRY. By DR. C A. 
 KEAXE, D.So, PaD^, F.LC Whh Diagrams. 
 
 TohunepiOTidesaninstnctrreand s^gestrre sanej of the great 
 
 TO-DAY'S ADDITIONS :- 
 
 THE CRIMINAL. By HAYELOCK ELLIS. Fourth Edition, 
 
 Revised and Enlarged. 
 XLYII. THE JEWS : A STUDY OF RACE AXD EXYTRONMEXT. 
 
 By Dr. MAURICE FlSHBERG. 
 "It shows abomvfiag evidence rnksprnjes that k kmteaded to show, 
 
 ftmmwBm*nC^ *fm*1n%f tT f JUHJlmmmJlg y^mo^ TASK titCTXIT ^*wJJ Cttl<lif^| lfV"1|fTy^, 
 
 ft contains, to be 'sare, anch infbrnmion of great vame, and it sets forth 
 many facts absorbing in their interest for any who desire to study the 
 
 absorbing 
 Jewbh peopled /* Ck?w:lc. 
 
 New York: CHAKUS SCUBXKR'S Sojss.
 
 IBSEN'S DRAMAS. 
 
 EDITED BY WILLIAM ARCHER. 
 
 THREE PLAYS TO THE VOLUME. 
 
 i2mo, CLOTH, PRICE $1.25 PER VOLUME. 
 
 " We seem at last to be shown men and women as they are ; and at fint it 
 is more than we can endure. . . . All Ibsen's characters speak and act as if 
 they were hypnotised, and under their creator's imperious demand to reveal 
 themselves. There never was such a mirror held up to nature before : it is 
 too terrible. . . . Yet we must return to Ibsen, with his remorseless surgery , 
 his remorseless electric- light ', until we, too, have grown strong and learned to 
 face the naked if necessary, the flayed and bleeding reality." SPEAKER 
 (London). 
 
 VOL. I. "A DOLL'S HOUSE," "THE LEAGUE OF 
 YOUTH," and "THE PILLARS OF SOCIETY." With 
 Portrait of the Author, and Biographical Introduction by 
 
 WlLLIAMARCHER. 
 
 VOL. II. "GHOSTS," "AN ENEMY OF THE PEOPLE," 
 and "THE WILD DUCK." With an Introductory Note. 
 
 ft>L. III. "LADY INGER OF OSTRAT," "THE VIKINGS 
 AT HELGELAND," "THE PRETENDERS." With an 
 Introductory Note, 
 
 VOL. IV. "EMPEROR AND GALILEAN." With an 
 Introductory Note by WILLIAM ARCHER. 
 
 VOL. V. "ROSMERSHOLM," "THE LADY FROM THE 
 SEA," "HEDDA GABLER." Translated by WILLIAM 
 ARCHER. With an Introductory Note. 
 
 VOL. VI. "PEER GYNT: A DRAMATIC POEM." 
 Authorised Translation by WILLIAM and CHARLES ARCHER. 
 
 The sequence of the plays in each volume is chronological ; the complete 
 set of volumes comprising the dramas thus presents them in chronological 
 order. 
 
 " The art of prose translation does not perhaps enjoy a very high literary 
 status in England, but we have no hesitation in numbering the present 
 version of Ibsen, so far as it has gone (Vols. I. and II.), among the very 
 best achievements, in that kind, of our generation." Academy. 
 
 "We have seldom, if ever, met with a translation so absolutely 
 Idiomatic." Glasgow Herald. 
 
 New York : CHARLES SCRIBNER'S SONS.
 
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