The Nature of Man: Studies in Optimistic Philosophy

8. Comparative Physiology of the Brain, etc. By JACQUES LOEB. WHEN Pasteur died a remarkable article appeared in one of the Paris newspapers. The writer described the intimate routine of the life at the Pasteur Institute, and compared it with that of a mediaeval religious community. A little body of men, forsaking the world and the things of the world, had gathered together under the compulsion of a great idea. They had given up the rivalries and personal interests of ordinary men, and, sharing their goods and their work, they lived in austere devotion to science, finding no sacrifice of health or money, or of what men call pleasure, too great for the common object. Rumours of war and peace, echoes of the turmoil of politics and religion, passed unheeded over their monastic seclusion ; but if there came news of a strange disease in China or Peru, a scientific emissary was ready with his microscope and his tubes to serve as a missionary of the new knowledge and the new hope that Pasteur had brought to suffering humanity. The adventurous exploits and the patient vigils of this new Order have brought about a revo- lution in our knowledge of disease, and there seems no limit to the triumphs that will come from the parent Institute in Paris and from its many daughters in other cities.

Elie Metchnikoff, now Professor at the Pasteur Institute in Paris, is one of the most distinguished of the disciples who left all else to follow Pasteur. He was born on the third (16) May, 1845, in a village of the Government of Kharkoff (Little Russia). He was educated at the Gym- nasium and the University of Kharkoff, passing through the Faculty of Science. From 1864 to 1870 he worked at Zoology at Giessen, Gottingen and Munich, successively under three well-known zoologists, Leuckhart, Henle and Von Siebold, and was then appointed Professor of Zoology and Comparative Anatomy at Odessa. He made expedi- tions to Madeira, Teneriffe and the Kalmuck Steppes in connection with his zoological researches. In 1882, in con- sequence of administrative difficulties, arising as part of the troubles that followed the murder of the Tzar, Alexander II., he resigned the Professorship and became Director of the municipal Bacteriological Laboratory. In 1888 he went to the Pasteur Institute, and has remained there since that time.

The earlier part of Metchnikoff's career was devoted to Zoology, and chiefly to investigation of the embryological history of the lower invertebrates, and the sequence of his discoveries should afford food for reflection to those Baconian economists who are unwilling to shelter any tree of know- ledge that does not give immediate promise of marketable fruit. The labour of many years spent in minute tracing of the development of insects, echinoderms, worms and jelly- fish, would appear sufficiently unprofitable to those who give a scanty support to Botany as the provider of drugs, who tolerate Chemistry because it has supplied aniline dyes, and who patronise the physical sciences from a lively sense of the convenience of telephones and telegraphs. And yet from these remote, inhuman interests, Metchnikoff, without intellectual transition, passed directly to results affecting vitally the human race, and became one of the high priests of Bacteriology and a guardian of the Pandora's box of modern times.

From observations made originally on water-fleas, he was led to discover the functions of the white corpuscles of human blood. He showed by what mechanism these made perpetual war against the intruding microbes of disease, and he laid the foundations of knowledge as to the agencies that weaken and the modes of strengthening these guardians of our health. In a series of investigations into the phenomena of inflammation in men and lower animals, he carried his observations into new fields, and explained the relations of the white corpuscles to the juices that attract and repel them (chemotaxis). It was he, for instance, who discovered that these corpuscles, under certain circumstances, migrate into the hairs and absorb and remove the pigment, so producing the blanching of old age. Although popularly the most in- teresting this was far from being the most important of the changes of senile decay that he found to be due to the activity of the wandering cells of the body. And, as will be seen in the present volume, the actions and interactions of the bacteria harboured in the body, the white corpuscles that are a natural part of the body, and the various juices or serums produced naturally or introduced by accident or design, are concerned in life itself and the decay of life.

Metchnikoff is an expert of experts in the science of life, and has gained the right to a hearing by forty years of pa- tient devotion and brilliant research. In the volume that he has now given to the public, he has addressed himself to the gravest and the most serious problems of humanity, to life and sex and death and the fear of death. From the earliest days when man could spare time from the satisfac- tion of his immediate wants to reflect upon his nature and destiny, these problems and the invention of fantastic solu- tions or evasive anodynes have absorbed his attention. The folklore and philosophy, the religion and poetry of all races

and of all stages of culture, from savage barbarism to de- cadent refinement, revolve round these obsessions of the mind, and, as Metchnikoff most plainly shows, no enduring comfort has yet been found. Now for the first time in the history of thought, the exact methods of science have been brought to the statement of the problems. In revising this translation of Metchnikoff's book for the English-speaking public I have had to content myself with seeing that the plain meaning of the French was transformed to plain English, and that references to French editions were changed, so far as was possible, to corresponding references to English editions. Some of the phrases that recur were difficult to express. "Human nature" for instance is not an exact equivalent of la nature humaine, for the latter phrase has a complete significance, and very definitely im- plies not only the mental qualities of man, but his bodily framework, with its inherited and acquired anatomical struc- ture and physiological functions. The phrase "human con- stitution," especially in the common medical sense, carries more of the meaning, and I have used it occasionally. The word "harmony " means harmony with the environment, and disharmony is want of harmony or imperfect adaptation to the existing environment. In the case of the human organism, which has passed through profound changes at a rate prodigious in the history of evolution, many parts of the constitution are no longer in gear with the existing environment, and it is in such disharmonies that Metch- nikoff finds the source of the troubles that have perplexed mankind.

In several parts of this volume, and particularly in the chapter dealing with disharmonies in the reproductive func- tions, there is much plain speaking on matters that modern civilisation attempts to conceal. I have not had the im- pertinence to suppress or to alter a line or a word of these pages. They are written in high seriousness on fundamental facts of the constitution of man ; they relate to problems and difficulties that every age in the history of man has had to face, and that are dealt with in the plainest language in the books of all the religions. For the first time proper knowledge has been brought to the task, and it is to be re- membered that this volume is an attempt to explain mys- teries of the flesh and of the spirit of which all existing explanations have failed to satisfy humanity. The volume is avowedly no more than a preliminary statement, a rally- ing-point for the work of future generations. But it awakens a new hope for humanity now that the old are fallen dumb; as Metchnikoff himself says, "If it be true that man cannot live without faith, this volume, when the age of faith seemed gone by, has provided a new faith, that in the all-powerful- ness of science." In every country, the new Order of priests of science, in the vigils of the laboratory, is working for the future of humanity.

In offering this book to you, reader, I feel that I must justify its publication. I admit freely that more could be said for a finished study in which hypotheses were replaced by exact fact. But to get together assured results in a field so little explored is a great task, calling for time and much labour. I remembered the adage, "Ars longa, vita brevis" and I decided to publish what is really a programme of work to be carried out as fully as circumstances may permit. At all events, I hope that such a programme may have its value for younger investigators, who wish a point of orien- tation for their labours.

My book is addressed to disciplined minds, and in especial to biologists. As I wrote it, I had not the general public in my mind, and so I did not hesitate to devote nearly the whole of a chapter to "disharmonies in the apparatus of reproduction." I see in that apparatus the clearest proof of the essential disharmony in the organisation of man. I have to thank those friends who were familiar with my views and whose advice and assistance have helped me to develop them.

In particular, I desire to thank my friends Dr. E. Roux, who was at the pains to make my French more French; and Dr. J. Goldschmidt and Dr. Mesnil, who have read and revised the proof-sheets. Importance of the study of the nature of man — The nature of man as the foundation of morality — Greek worship of human nature — Matriopathy of ancient philosophers — Rationalism of the eighteenth and nineteenth centuries — Degradation of human nature by religious doctrines — Influence of these con- ceptions on actual life and on art — Reaction of the Reforma- tion against the degradation of human nature — Mutilation of the human body by primitive races

The organised world before the appearance of man on the earth — Absence of a law of universal progress— Fertilisation of vanilla — The part played by insects in the fertilisation of orchids — Mechanism by which insects carry the pollen of orchids— Habits of fossorial wasps — Harmonies in nature — Useless organs — Rudiments of the pollinia of orchids — Disharmonies in nature — Unadapted insects — Aberration of instincts— Perversion of sexual instinct— Attraction of insects by light — Luminous insects — Law of natural selection — Happiness and unhappiness in the organised world

Relationship of the human species with anthropoid apes — Analogies in the dentition, in the organisation of the limbs and of the brain — Resemblance of the vermiform appendage of man and anthropoids — Analogy between the placenta and foetus of man and anthropoid apes — Blood relationship of man and monkeys shown by serums and precipitates — Transmu- tation of species — Sudden transition from monkey to man — J. Inaudi, the calculator, as an example of the sudden appear- ance of characters in the human species — Rudimentary organs in man — Proportion of progressive and retrogressive organs in the organisation of man

Perfection of the human form — The covering of hair — the dentition in general, and the wisdom-teeth — The vermiform appendage — Appendicitis and its gravity — Uselessness of the CJecum and of the large intestine — Instance of a woman without a large intestine — Ancestral history of this portion of the digestive tract — Injurious effect of the microbes of the large intestine- -Frequency of cancer of the large intestine and of the stomach — Limited usefulness of the stomach — The instinct of choice of food — Futility of this instinct in man

Remarks on the disharmonies in the human organs of sense and perception — Rudimentary parts of the reproductive apparatus — Origin and function of the hymen Evolution and significance of the menstrual flow in women- Precocious marriage amongst primitive and uncivilised races — Disharmony between age of puberty and age of nubility — Age of marriage — Examples of disharmony in the development of the reproductive function Disharmonies in the family instincts — Artificial abortion — De- sertion and infanticide — Disharmonies in the social instincts

The instinct of self-preservation in animals — Man's instinctive love of life — Indifference to life during childhood — Buddhist legend on instinctive self-preservation and the fear of death — Fear of death treated in literature — Confessions of Tolstoi regarding the fear of death— Other opinions on the subject — The fear of death an instinctive phenomenon — Development in man of a love of life — Treatment of the aged — Murder of old people — Suicide of old men — Absence of harmony between the love of life and the conditions of human existence — The part played by the fear of death in religions and systems of philosophy

Animism as the foundation of primitive religions — The Jewish religion in relation to the doctrine of immortality of the soul — The religions of China — Ancestor worship in Confucianism - — The conception of immortality in Taoism — The persistence of the soul in the Buddhist religion — The paradise of the Chinese Buddhists — Ancestors worshipped as gods— Influence of religious faith on the fear of death — Pessimism of the doctrine of Buddha — The meaning of Nirvana — Resignation as preached by Buddha — Objections to immortality of the soul — Irritability of the tissues and cells of the body — Religious hygiene — Religious means of controlling the repro- ductive functions and of preventing diseases — Failure of religions in their attempts to combat the ills arising from the disharmonies of the human constitution

Some philosophical systems are in intimate union with religions —Ideas of ancient philosophers on the immortality of the soul —The teaching of Plato— The scepticism of Aristotle— The Stoics — Cicero, Seneca, Marcus Aurelius — Modern philoso- phical systems— Pessimism and its origin— Lord Byron— Theories of Schopenhauer and Hartmann— Mailaender's philosophy of deliverance— Criticisms of pessimism— Max Nordau— Ideas of modern thinkers on death Formation of the experimental method — The intervention of religion in disease— Disease as a basis of pessimistic systems of philosophy — Advance of medical science in the war against disease — The revolution in medicine and surgery due to the discoveries of Pasteur — The beneficial results of Serum Therapy in the war against infectious diseases — Failure of science to cure tuberculosis and malignant tumours — Protests against the advance of science — Opposition of Rousseau, Tolstoi and Brunetiere — Proclamation of the fallibility of science — Return to religion and mysticism

INTRODUCTION TO THE SCIENTIFIC STUDY OF OLD AGE . . . 228 General account of old age — Theory of senile degeneration amongst unicellular organisms — Conjugation amongst infusoria — Old age in birds and in anthropoid apes — General characters of senile degeneration — Sclerosis of the organs — Phagocyte theory of senile degeneration — Destruction of higher elements by macrophags — Mechanism of whitening of the hair — Serums acting on cells (cytotoxins) — Sclerosis of the arteries and its causation — Harm done by the microbes of the alimentary canal — Intestinal putrefaction and the modes of preventing it — Attempts to prolong human life — Longevity in biblical times

INTRODUCTION TO THE SCIENTIFIC STUDY OF DEATH . . . 262 Theory of the immortality of lower organisms — Immortality of the sexual cells io higher organisms — Immortality of the cellular soul — Occurrence of natural death in the case of certain animals — Natural death in the Ephemeridae — Loss of the instinct of preservation in adult Ephemerids — Instinct of life in the aged — Instinct of natural death in man — Death of old men in biblical times — Changes in the instincts of man and lower animals

Disharmonies in the human constitution as the chief source of our sorrows — Scientific data as to the origin and destiny of man — The goal of human existence — Difficulties in the way of scientific investigation of the problem, What is progress ? — Difficulty of including the whole human rate in a scheme of progress and morality — The instincts of life and of natural death — Application to real life of the doctrines set forth in this book 14. Section of a renal tubule invaded by Maorophag* . , , 241

Importance of the study of the nature of man — The nature of man as the foundation of morality — Greek worship of human nature — Matriopathy of ancient philosophers — Rationalism of the eighteenth and nineteenth centuries — Degradation of human nature by religious doctrines — Influence of these conceptions on actual life and on art — Reaction of the Reformation against the degradation of human nature — Mutilation of the human body by primitive races

NOTWITHSTANDING the real advance made by science, expressions of discontentment with it are familiar. Science, it is said, no doubt has ameliorated the material conditions of human life, but is powerless to solve those moral and philosophical questions that interest cultured people so deeply. In this region science has done no more than to destroy the foundations of religion. It has robbed man- kind of the consolations of religion without being able to replace them with anything more exact or more enduring.

It cannot be disputed that a general uneasiness disturbs the world of to-day. Although his environment is most favourable to the fulfilment of many of his capacities, man finds himself without orientation when he has to determine the course of his life, or to explain to himself his true rela- tion to such categories of humanity as family, nation, race and human race. This uneasiness reveals itself as discontentment, and it leads to pessimism or to mysticism. Most of the philosophical systems of the nineteenth cen- tury were steeped in melancholy, and led straight to a denial of the possibility of happiness and even to an advo- cacy of extinction. The frequency of suicide has increased greatly among all the civilised peoples. There is no need to tabulate proofs of a notorious fact.*

A remedy for this malady of the age has been sought in the attempt to restore religious and mystical faith. On ah1 sides have sprung up efforts to found new religions or to amend the old. Many defenders of science have gone the length of admitting its incapacity to solve the problem of the existence of man ; they have held that that problem was insoluble for the human mind. Such a depressing conclusion has been formulated in spite of many attempts to reach a rational conception of the universe and of man.

It is no new thing to ask if there be nothing but faith to control human conduct and to lead mankind towards universal happiness. Men of science and philosophers, in many ages, have thought that human nature itself could provide all the materials for a rational morality. In the ancient world and, above all, among the Greeks, human nature was held in high esteem. The Oriental races, predecessors of the Greeks in civilisation, generally represented their gods as fantastic or grotesque beings, composites of men and animals. The Greeks made gods

* Since A. Wagner's classical work, " Ueber die Gesetzmassigkeit der scheinbar wilkurlichen menschlichen Handlungen," suicide has been discussed by many authors. The most recent contribution to the subject is the important monograph by Westergaard, " Die Lehre von der Mortalitaet u. Morbiditaet," Second Edition, Jena, in their own image, giving them all the most beautiful qualities of the human race. Such a conception was a dominant factor in ancient Greek life and civilisation. The adoration of Man embraced the human body, and led to the despising of every mode of tampering with the natural body. Thus, for instance, shaving * of the face was regarded as a humiliation, for a smooth chin gave an unnatural, womanish cast to the face of a man.

The adoration of human nature by the Greeks appeared in Greek plastic art, and was the cause of its excellence. The ideal of art was to copy, in the most faithful way, the most perfect example of the human body, and Greek artists made measurements of the body so accurately that modern science has confirmed their chief results, f As sculpture most completely realised the Greek ideal of the human body, it became almost a national art among the Greeks.

Greek philosophy had an equally high opinion of human nature, of the human body, and of representations of the human body. Just as Greek art aimed at the presentation of the body of man, so Greek philosophy proclaimed the nobility of all human qualities, and inculcated the doctrine of a harmonious development of all sides of human nature. | Such a doctrine was formulated by Plato, and became a fundamental principle of the Old Academy ; the New Academy assumed it, and handed it on to the Sceptics. According to Xenocrates (fourth century), who

* Shaving the beard began at the time of the Macedonian rule, and philosophers refrained from the new custom, which seemed to them unprincipled. (V. Hermann, " Lehrbuch der griechischen Privatalterthiimer," 1870, vol. I., pp. 175-177.) belonged to the Old Academy, happiness consisted not only in the possession of human virtue, but in the accom- plishment of all natural acts.* The principle of a worship of human nature is in itself rather vague, and it is not surprising that disputes and con- tradictions arose in relation to its application. Thus Plato excluded pleasure from his conception of the good, while Aristotle, Plato's pupil, held a contrary opinion. For the latter pleasure was the natural motive of human action, and its attainment was associated as intimately with the perfect life as beauty and health were associated with the perfect human body.f

Under the name Matriopathy there arose, in the ancient world, a doctrine the object of which was the study of the goal of natural morality. This doctrine was held by many philosophers, but these applied it to the details of actual life in very different fashions. Thus, for the Stoics, the summum bonum and happiness, the most lofty aim, could not be found except by conforming life to nature. Conduct was to be brought into harmony with the rational order of nature in such a fashion that every conscious and rational being would perform no actions that could not be deduced from the general law.j The same principle of a life in harmony with nature led the Epicureans to the conclusion that " pleasure is a natural good, that is to say, a condition conformable with nature, and so bringing with it intrinsic contentment." § Setting out from the same fundamental principle, the theories of the Stoics and Epi- cureans led in opposite directions.