Chapter 4

[1]"Science et Méthode," p. 101.

[2]Part III of "The Value of Science."

[3]M. Poincaré, in relating these experiences for their psychological interest, was kind enough to say that the non-mathematical reader need not be frightened at these barbarous names, for it is not at all necessary for him to know what they mean.

[4]Dr. Toulouse has devoted a volume of his series of medico-psychological studies of men of genius to observations on the memory, reaction time, mode of thinking, habits, and physiological constitution of Henri Poincaré (Paris: Flammarion).

[5]Revue des Idées, 1909, p. 488.

[6]Masson's address may be found in Le Bon's bibliography; also inPopular Science Monthly. An entertaining account of Poincaré's reception into the Academy was written forLe Figaroby André Beaunier and translated for the BostonTranscript.

[7]Revue bleue, June 4, 1907, p. 708.

[8]La Revue, 1910.

[9]Translated by Professor Halsted from "Science and Morals" inDernières Pensées.

Ever since the attempt has been made to discover a rational basis of morality, human nature, regarded essentially as good, has been taken as that basis. Religions and systems of philosophy, on the other hand, which have tried to find another foundation for morality, have regarded human nature as vicious at the roots. Science has been able to tell us that man, the descendant of animals, has good and evil qualities in his nature, and that his life is made unhappy by the evil qualities. But the constitution of man is not immutable, and perhaps it may be changed for the better.Morality should be based not on human nature in its existing vitiated condition, but on human nature, ideal, as it may be in the future. Before all things, it is necessary to try to amend the evolution of the human life, that is to say, to transform its disharmonies into harmonies (Orthobiosis). This task can be undertaken only by science, and to science the opportunity of accomplishing it must be given.—Metchnikoff's "The Nature of Man", p. 288.

Morality should be based not on human nature in its existing vitiated condition, but on human nature, ideal, as it may be in the future. Before all things, it is necessary to try to amend the evolution of the human life, that is to say, to transform its disharmonies into harmonies (Orthobiosis). This task can be undertaken only by science, and to science the opportunity of accomplishing it must be given.—Metchnikoff's "The Nature of Man", p. 288.

If Carlyle were writing now his "Heroes and Hero-Worship", he would have to add—however much he would have disliked to—a chapter on "The Hero as Scientist." For the popular ideal of greatness has been decidedly changed in the last half-century, and new standards of heroism have been established. Creative genius is beginning to take rank above destructive, and men are coming to recognize that the heroism of those who save life may be quite as great and is certainly more admirable than the heroism that is measured by a monument of skulls. A striking proof of this shifting of public appreciation is afforded by the referendum carried out by thePetit Parisiena few years ago to ascertain whom the French people regarded as the greatest names their country had produced during the nineteenth century. Fifteen million answers were sent in, so the result may be taken as representing the consensus of opinion in a larger degree than such newspaperplebiscitesgenerally do. It was to be expected that the name of Napoleon would head such a list. It would have in almost any other country except France. But France, always devoted to the cult ofLa Gloireand hitherto chiefly captivated by the bellicose form of it; France, where every man is trained in the army and educated in schools established with the avowed purpose of increasing the military strength of the nation; France ranks Napoleon fourth in the list of eminent men and puts at the head of it the name of a modest chemist and physiologist, Louis Pasteur.[1]It is a common observation that new ideas and social tendencies are apt to become manifest in France earlier than elsewhere. The French clock seems to be fast, always keeping a bit ahead of mean European time. If so, we may expect that before long other countries may come to give due honor and, what is more important, due opportunity and encouragement to the scientists, inventors, and authors who confer glory upon their country by benefiting the whole world.

The worthy successor of Pasteur as Director of the Institute he founded is the subject of this sketch, Élie Metchnikoff. The foremost of French medical men, he was neither born a Frenchman nor trained as a physician. Like Pasteur, he entered the realm of medicine by crossing the frontier of another science. Any man who pursues a straight line of thought will find that it leads him across many of those imaginary lines which have been drawn between the sciences, just as an aviator crossing Europe in an air line pays no attention to the artificial and historic boundaries which divide state from state. Pasteur was a chemist, an inorganic chemist at that, and he was running down the cause of asymmetry in crystals when he found himself over in the field of biology. He had been engaged in separating the leftward skewed crystals of tartaric acid from those that skewed to the right by picking them out of the mixture by hand, but he discovered that he could throw the burden of selection off on an agency whose time was less valuable, namely, the yeast plant, which has an appetite for one kind of crystals, but disdains the other. This led him to the germ theory of life and of disease and enabled him to save millions annually to the farmer and stockraiser and unnumbered human lives.

Metchnikoff's experience was similar. He was as a zoölogist less interested in man than in the invertebrates, devoting his time to the study of the minuter forms of life on the barren steppes of Russia and in Mediterranean waters. It was in Italy at Messina in 1882 that he made the discovery which led him to fame as one of the benefactors of the human race. Now, if a man should deliberately set out for such a goal, if he should be incited by egotism to become famous, or inspired by altruism to relieve the suffering of humanity, about the last thing he would try would be to sit down in a laboratory all day with his eye glued to a microscope watching the blood corpuscles chase each other through the veins of an infant starfish. But since Metchnikoff was less influenced by the two motives mentioned than he was by a desire for truth for its own sake and regardless of consequences, all these things have been added unto him. If the anti-vivisectionists had their way about it, experimentation in animals, if allowed at all, would be restricted to physicians and to the specific purpose of curing disease. This, however, would be one of the surest ways to check medical progress, for the advancement of a science ordinarily owes little to those who are professionally engaged in its practice or have their eyes focused upon some practical result of their investigations. At least the world may rejoice that through the liberality of French law the work of these two men has never been hampered—Pasteur, who discovered the cause of disease, and Metchnikoff, who discovered the cause of immunity. These are two cornerstones of the foundation on which is now being erected the structure of a rational system of hygiene the purpose of which is to prolong human life by the elimination of disease rather than by its cure. The change that is taking place in medicine is analogous to that taking place in philanthropy. The modern philanthropist appears cold-hearted because, instead of dropping a coin into a beggar's hat, as did the charitable in former days, he devotes himself to a systematic study of the causes of poverty. The modern medical man is likewise misunderstood if he seems indifferent to the suffering around him and is absorbed in the investigation of remote biological problems having no perceptible relation to human needs. But the beneficial results of the scientific method in both philanthropy and medicine are already sufficiently apparent to enable us to see that it will do much more for humanity than the kind but blind benevolence of the past.

The fame of France in art, literature, and science is in large part her reward for her hospitality in giving to men of other lands the freedom and encouragement which they could not find at home. One example is Maeterlinck. Another is Metchnikoff. He left his native country chiefly because of a difference of opinion on political questions between himself and the Czar. Not that he has ever been a revolutionist, but as a Jew by race, an atheist in religion, and a liberal in politics, he was triply obnoxious to the powers that be, and after the assassination of Alexander II in 1881, the students were too much excited over politics to attend to their studies. So he resigned his professorship in the University of Odessa and went abroad to devote himself to biological research.

He was born in the Province of Kharkov, Little Russia, May 15, 1845. His father was an officer of the Guards, afterward a general. His mother was a Jewess, and it was from her that he derived the love for science which early manifested itself. He won a gold medal in the high school of Kharkov and passed through the university of that city in two years instead of the customary four. Then he went to Germany and studied at Giessen, Göttingen, and Munich. Returning to his native land, he taught in the University of St. Petersburg and in 1870 went to Odessa to take the chair of zoölogy in the university there.

The years spent in private study, chiefly at Messina, the earthquake city of Sicily, were most fruitful, for his investigation of intercellular digestion in minute marine invertebrates gave him the clew to the protective action of the blood in the higher animals and man, and in 1884 he outlined his theory of inflammation, which was, in short, that the congestion of blood at a wound was due to the efforts of the leucocytes or white blood cells to overpower the invading microbes. The value of this discovery was recognized immediately by the two foremost authorities in biology: Virchow, the German, who had discovered the leucocytes, and Pasteur, the Frenchman, who had discovered the microbes. Metchnikoff had now found the missing link which brought these two discoveries together and showed their meaning.

In 1888 Metchnikoff was called to the Pasteur Institute, and in 1895 became its director. Here he found an exceptional opportunity to devote his talents to the relief of suffering humanity. Such institutions for the advancement of the science of medicine have since been established elsewhere: the Institute for Experimental Therapeutics in Frankfort-on-the-Main, the Cancer Research Laboratory of London, the Rockefeller Institute in New York, for example; but the French people were the first to respond to the need of the man they have delighted to honor by endowing, in 1886, an institution which should continue his work as well as perpetuate his name. The Nobel prize for the most important discovery in medicine was in 1908 divided between Metchnikoff, of the Pasteur Institute, and Professor Paul Ehrlich, of the Frankfort Institute, who has in these latter days made "606" the mark of the beast, instead of 666, as prophesied in Revelation. The Nobel prize man of 1912, Doctor Alexis Carrel, although a Frenchman by birth, found in the Rockefeller Institute the opportunity to carry on his remarkable investigations on the preservation and transplantation of living tissues.

Characteristically French is the artistic setting which has been given to this home of science. The visitor appropriately approaches it through the long and handsome Boulevard Pasteur, then turning into a side street he finds on his left the Pasteur Institute and on his right the more imposing buildings of the Institute for Infectious Diseases and the Laboratory of Biological Chemistry, recently erected for carrying out the treatment which the experimental work of the other side of the street has suggested. A new department has been added for the study of tropical diseases such as the sleeping sickness, which has depopulated a large part of the Nyanza region. This extension of the work is made possible by the receipt in 1909 of the bequest of eight million dollars by the miserly and eccentric Jewish banker who called himself Osiris.

As the visitor passes into the courtyard of the Institute, his nerves already shaky with thoughts of microbes and mad dogs, he is almost startled to see, half hidden among the trees, a man engaged in a death struggle with a wolf. This is a bronze statue of Jupile, a shepherd who, bitten by a mad wolf, was one of the first patients to receive the Pasteur treatment for rabies. In a crypt of marble and mosaic underneath the building is the tomb of Pasteur, as impressive, if less imposing, than the tomb of Napoleon under the dome of the Invalides not far away. The reception room of the Institute is adorned with large paintings showing the modern miracles of healing, better authenticated than those of Sainte Geneviève depicted by Puvis de Chavannes on the walls of the Panthéon.

Professor Metchnikoff is ordinarily not accessible to visitors, especially interviewers, but since I was armed with a letter of introduction from Professor Jacques Loeb, of the Rockefeller Institute, whom he regards as the foremost of American scientists, I was fortunate enough to find him in.

He has rather a short figure and a large head, with a bushy gray beard, but hair that is still dark. His spectacles are not sufficient to impart severity to his mild blue eyes. His voice is low and pleasant, and he speaks, as he moves, without either hurry or hesitation. He is a worker among workers, inspiring with his indefatigable zeal the young men who come to him from Europe, America, and Asia to pursue their researches in bacteriology.

A walk through the Pasteur Institute is like a visit to a zoölogical garden, for the study of each particular human disease requires the discovery of some species that is also susceptible to it. Here are not only the dogs, guinea pigs, and rats common to every bacteriological laboratory, but also many others closely connected with Metchnikoff's special interests; parrots and geese, for example, which are remarkable for their longevity; bats, which eat rotten food and yet maintain an aseptic intestinal tract; and chimpanzees, which, as the literal blood relations of man, are capable of sharing the worst of his diseases.

Like Agassiz, Metchnikoff has "no time to get rich." At his home in the suburbs of Paris he sets an example of the plain living he advocates, supplementing the meager salary given him at the Institute by the income of a small estate in Russia. The twenty thousand dollars he received from the Nobel Foundation he devoted entirely to the furtherance of his researches in longevity.

M. Metchnikoff has given the best possible proof that he has no personal aversion to women who enter his profession, for he married in 1875 as his second wife a Russian bacteriologist of distinction. He dedicated to her his first volume of "Optimistic Studies," and in it he cites her experiments on the growth of microbe-free tadpoles. She is an artist as well as a scientist, and here, too, M. Metchnikoff shares her tastes, for he is fond of painting and music. They have no children, but he has a godchild to whom he is devoted.

His high regard for individuality leads him to look with favor upon the entrance of women into the universities and the professions. He has no fear that it will result in the production of a class of celibates corresponding to the sexless workers of the beehive. On the contrary, his observation of the feminist movement for more than forty years has shown him that learned ladies are by no means wanting in the marital and maternal instincts common and proper to their sex. Of a thousand women in the St. Petersburg Medical School, ten per cent had been married before, and forty-four per cent were married during their course of study. A conspicuous case of feminine scientific genius is that of Sonya Kovalevsky, who attained the highest eminence in that field which, by the common consent of men, was formerly regarded as unattainable by women; that is, pure mathematics. But the day when she received the doubled prize of the French Academy of Sciences she wrote to a friend that she had never felt so unhappy, and the cause of her unhappiness, as revealed in her letters and romances, was that she was not beloved as other women were.

Although Metchnikoff would grant to women every opportunity for the exercise of their talents, and thinks they had better occupy themselves with science than with fashions, he believes genius of a high order to be much rarer among them than among men. When he was called upon by the women doctors and scientists at the Naturalists' Congress at St. Petersburg for his opinion of the feminist movement, he created considerable consternation among them by the following frank language:

Your complaint, as I understand it, is that man has excluded woman from all higher intellectual occupation by unnatural means, so that her mind has become atrophied, her capabilities blunted, her talents stagnant. You would remedy all this by being made man's equal in politics. You would then, you say, develop your slumbering abilities, overtake, and possibly surpass, your immemorial enslaver—man.But do you really need this political equality in order to attain this supremacy? Has the down-trodden among men ever needed it? His political equality has come as an effect not as the cause of his intellectual development. The mind that dominates in the artistic and scientific world ultimately arrives at political supremacy.But what art or science has man closed to you? You are here; but really, ladies, I have failed to discover a Bichat, a Louis, a Jenner, or a Pasteur among you. Have you personally been impeded in your careers more than certain individuals among men? Now let us take the arts. Is there a man-master so unnatural who ever forbade his female slave to express herself in music? But where are your Beethovens, your Wagners, your Verdis, your Brahms? I beg of you, dear ladies, if you remember one, tell me.What brutal slave owner at any time forbade women to beautify canvas with satisfying hues and lines depicting life or nature? As in music, man has encouraged women to do these things, yet where are your Raphaels, your Leonardos, your Rubenses? Have women been forbidden to mold, carve, or draw? Yet where is your Phidias, your Michelangelo, your Cellini? Did you ever hear of a woman architect?Home and motherhood there, of course, the most radical among you will not say that man has attempted to restrain you—there you have had from time immemorial, in all ages, in all places, under every condition, absolute and full freedom. Still, is it not man, the enslaver, who teaches you domestic economy? Is it not from man that you have learned how to care for your offspring in illness, how to amuse them in health? Who discovered the laws of domestic hygiene? Was it a woman?Now, my dear ladies, has man ever excluded you from the kitchen? No, you say, you have been enslaved there. "Cook! Feed the brute!" is eternally dinned in your ears. It would seem reasonable that at least in this sphere woman should have reached a high standard of perfection. And the actual result? Ah, dear ladies, I must confess. If I want a really good dinner I must have recourse to a chef.And now, ladies, I ask your pardon, you have all studied physiology and psychology, and you know where such considerations would lead me. But one word more: Do not lose sight of the significance of your request, "Professor, what is your opinion of the feministic movement?" for that makes out your case perfectly—to advocate your cause you would call in the help of man.

But do you really need this political equality in order to attain this supremacy? Has the down-trodden among men ever needed it? His political equality has come as an effect not as the cause of his intellectual development. The mind that dominates in the artistic and scientific world ultimately arrives at political supremacy.

But what art or science has man closed to you? You are here; but really, ladies, I have failed to discover a Bichat, a Louis, a Jenner, or a Pasteur among you. Have you personally been impeded in your careers more than certain individuals among men? Now let us take the arts. Is there a man-master so unnatural who ever forbade his female slave to express herself in music? But where are your Beethovens, your Wagners, your Verdis, your Brahms? I beg of you, dear ladies, if you remember one, tell me.

What brutal slave owner at any time forbade women to beautify canvas with satisfying hues and lines depicting life or nature? As in music, man has encouraged women to do these things, yet where are your Raphaels, your Leonardos, your Rubenses? Have women been forbidden to mold, carve, or draw? Yet where is your Phidias, your Michelangelo, your Cellini? Did you ever hear of a woman architect?

Home and motherhood there, of course, the most radical among you will not say that man has attempted to restrain you—there you have had from time immemorial, in all ages, in all places, under every condition, absolute and full freedom. Still, is it not man, the enslaver, who teaches you domestic economy? Is it not from man that you have learned how to care for your offspring in illness, how to amuse them in health? Who discovered the laws of domestic hygiene? Was it a woman?

Now, my dear ladies, has man ever excluded you from the kitchen? No, you say, you have been enslaved there. "Cook! Feed the brute!" is eternally dinned in your ears. It would seem reasonable that at least in this sphere woman should have reached a high standard of perfection. And the actual result? Ah, dear ladies, I must confess. If I want a really good dinner I must have recourse to a chef.

And now, ladies, I ask your pardon, you have all studied physiology and psychology, and you know where such considerations would lead me. But one word more: Do not lose sight of the significance of your request, "Professor, what is your opinion of the feministic movement?" for that makes out your case perfectly—to advocate your cause you would call in the help of man.

Metchnikoff has very little liking for the political methods in vogue in our republics. He thinks young men too reckless, opinionated, and pessimistic to be intrusted with the ballot at the age of twenty-one. "It is easily intelligible," he says, "that in the new conditions such modern idols as universal suffrage, public opinion, and the referendum, in which the ignorant masses are called upon to decide questions which demand varied and profound knowledge, will last no longer than the old idols. The progress of human knowledge will bring about the replacement of such institutions by others in which applied morality will be controlled by really competent persons." But he fails to inform us how these "competent persons" are to be selected and placed in power.

To give an account of the varied researches which Metchnikoff has carried on or has superintended at the Pasteur Institute is apart from our purpose and would in any case be impossible here, because it would involve the recapitulation of a great part of the history of medical progress for the past quarter century. During this period the science of medicine has been completely revolutionized, for the use of traditional and empirical remedies has been largely replaced by a systematic search for the causes of diseases and the experimental determination of methods of avoiding or counteracting them. In general, the change may be characterized as a return to nature. In the older medicine at its best, a dose of some vegetable or mineral substance, such as quinine or mercury, comparatively harmless, but altogether foreign to the body, was administered through the mouth and in time reaching the blood through the digestive systems, killed off or paralyzed the disease germ. In modern medicine at its best, some substance, such as the diphtheria antitoxin, that is already present in the blood in quantity sufficient under ordinary circumstances to prevent infection, is reënforced in an emergency by more of the same substance prepared in the blood of the horse. Or if that cannot be done, the next best thing is to inject some serum that by a natural reaction will stimulate the body to prepare in excess its own antitoxin or excite the phagocytes to greater exertions in overcoming their enemies. In any case, the object is to induce an artificial immunity as nearly as possible like the natural immunity of the healthy body.

Phagocytes—that is, "devouring cells"—was the name given by Metchnikoff to the leucocytes or white cells, which he found wandering about the body in search of their prey. They lead a sort of semi-independent life, like the simplest one-celled animal, the amoeba, and they penetrate to all parts of the body, even squeezing in between the toughened tissue of the skin and bones. When a cut is made in the skin they are borne to the breach by the flow of blood and there pile up and coagulate, forming a new skin to protect the raw flesh, somewhat as a breach in a rampart is hastily filled in with sand bags. Not only that, but when the enemy actually gains entrance either by storming a wound or sneaking in through some unguarded opening, then the white cells rally to the attack, surrounding and destroying the invading microbes. If these multiply too rapidly, the phagocyte reserves are mobilized, new recruits by the million are called out, until the bodily force is victorious or exhausted. Such a battle we call a local inflammation, or, if the engagement is general and long continued, a fever. Under the microscope we may watch the foes engaged in single combat, the phagocyte devouring the bacillus, a living, formless mass of protoplasm stretching out extemporized tentacles and engulfing the rod, globe, or writhing spiral which we may afterward see slowly digesting in its interior.

To be sure, the operation is not quite so simple as Metchnikoff first conceived it. A condition is always more complicated than the theory devised to explain it. The question has been hotly debated and is not yet settled whether the phagocytes best defend us by their life or by their death. It appears that as they undergo dissolution they give up to the blood certain substances which dissolve the disease germs or neutralize their poisons, and this may be a more important means of defense than the englobing or engulfing process. Then, too, these white cells seem at times strangely indifferent to the presence of their dearest foes, or, perhaps we should say, their favorite food. There is needed in the blood on such occasions a substance known as opsonin, which being absorbed by the microbes the phagocytes attack them with avidity; this opsonin serving as some biologist, doubtless an Englishman, has said, like Worcestershire sauce as an appetizer to the phagocytes.

But for further discussion of these questions I must refer the reader to his family physician, who will take pleasure in repudiating these vague and fanciful interpretations of mine. He will be able to tell whether phagocytosis or bacteriolysis is the fashionable mode of combating disease germs and he will introduce the reader to alexin, agglutinin, anti-bodies, sidechains, and other interesting and useful novelties that he contains within him to a greater or less degree, let us hope a greater.

But these same voracious white blood cells which ordinarily serve as the defenders of the body may in the period of its weakness become its worst enemies. This reminds us of the Prætorian Guards who in the later days of Rome precipitated its decline by attacking the capital. The phagocytes show an unfortunate predilection for the higher elements of the human organism and, according to Metchnikoff, the most distressing symptom of old age, the weakening of the mind, is due to their devouring the nerve cells. But besides that they play havoc all through the body; eating up the pigment of the hair and so whitening it; causing degeneration of the liver and kidneys; robbing the skeleton of its lime and depositing it in the blood vessels, thus doing double damage by weakening the bones and hardening the arteries. In these symptoms of senility the germs of disease form an important factor, both in weakening the body and instigating the treacherous insurrection of the phagocytes. Hence Metchnikoff comes to the conclusion that: "The senile degeneration of an organism is entirely similar to the lesions induced by certain maladies of a microbic origin", and thus he arrives at his famous definition: "Old age is an infectious chronic disease, characterized by a degeneration or an enfeebling of the noble elements and by the excessive activity of the phagocytes."

If old age is correctly characterized as a disease, and especially if it is due in part to microbic invasion, it ought to be possible to cure or postpone it. This, then, is what Metchnikoff has in recent years made the main aim of his researches.

In particular he suspects the large intestine of harboring some of the most dangerous of the microscopic enemies of man, the cause of many of the ills that flesh is heir to. It is in his opinion an excessive and comparatively unimportant organ, for it can be shortened or removed without serious consequences. A comparative survey of the anatomy of the vertebrates shows that as a general rule the longer the intestine the shorter the life. He does not advocate its extirpation by surgery or its disinfection by chemicals, but he would crowd out its wild and poisonous flora by harmless cultivated species. Among the friendly microbes he regards the lactic acid bacilli as most useful for this purpose. These act upon milk or fruit sugar, converting it into lactic acid, which is destructive to most other microbes, including some of the most dangerous. For example, mysterious outbreaks of typhoid fever have been recently traced to "typhoid carriers"; that is, persons who, while immune to the disease themselves, may yet serve for years as conveyors of the infection. But a thriving colony of Bulgarian bacilli will drive out the typhoid bacilli and so put a stop to the spread of the disease.

The difference between harmless and injurious bacteria on which the lactic acid theory depends is easily understood because it is a matter of common observation. Meat and milk have much the same composition so far as their protein is concerned. But whereas meat promptly spoils, that is, putrefies, with the formation of disgusting and poisonous products of decomposition, milk sours instead and will remain wholesome and to some tastes palatable for several days. Both are the results of bacterial decomposition, but the difference is due to the fact that milk contains a kind of sugar which, inoculated with the proper bacilli, is converted into lactic acid, and thus the growth of the bacteria of putrefaction is for some time prevented. But under certain circumstances it happens that the latter get the start of the lactic acid makers, and then the milk goes the way of the meat, and we have a case of "ptomain poisoning." In short, the aim of swallowing cultures of lactic acid bacilli by whole-sale is to keep the contents of the remote regions of our digestive apparatus in the condition of soured milk rather than that of decayed meat. Recently the same treatment has been recommended for preserving the teeth, since these mild-mannered and beneficent bacilli rubbed into the gums will dispossess those which ordinarily grow in our mouths and attack our teeth.

For aid in his fight against the bacterial poisons that bring on disease and old age, Metchnikoff has resorted to his native steppes. The Tartars and Kalmucks of southern Russia had always had as their favorite food koumiss, prepared by the fermentation of mare's milk, and nomads of all races have made use of some form of curdled milk, chiefly because of the difficulty of preserving other kinds of animal food under primitive conditions. The keffir of the Caucasus, the leben of Egypt, the matzoon of Armenia, the dadhi of India, and yahourth of Bulgaria are all produced from milk by the use of various species of lactic acid bacilli associated with other bacteria of fermentation. Of these the last, the Bulgarian yahourth, yoghourt, or yagurt, contains the strongest bacilli; that is, those that are able to stand the largest percentage of the product of their own activity, lactic acid, and so Metchnikoff has made them the basis of his dietetics.

A surprisingly large proportion of centenarians are reported from Bulgaria, where yagurt is used, and Metchnikoff cites a large number of cases of men and women of extreme old age who have lived largely on sour milk or on sauerkraut, which also contains the lactic acid bacilli.[2]Most of these are found among the poorer classes or comparatively uncivilized races. Sir Moses Montefiore is one of the very few rich men who have passed the century mark. Metchnikoff uses this as an argument for the simple life. But it is questionable whether such data, derived from the casual reports of individual cases and the generalized observations of travelers, are of much evidential value. Claims to longevity among the unlettered are notoriously unreliable. It would be very unsafe to hold that the negroes were longer lived than the whites, because so many mammies could tell of remembering Washington. When the British old age pension bill passed, the number of poor people in Ireland who came forward with evidence that they were over sixty-five years old surprised the actuaries and embarrassed the budget. Women are apt to restore double-fold in old age the years they deprived themselves of in the later thirties.

It is also curious to see a skeptic like Metchnikoff giving serious consideration to the accounts of longevity given in the Pentateuch which many orthodox theologians are willing to concede as legendary. He balks, indeed, at Noah's nine hundred and fifty years and Methuselah's nine hundred and sixty-nine, but accepts as probable Aaron's one hundred and twenty-three years and Moses's one hundred and twenty, quoting the words of Jehovah: "My spirit shall not always strive with man for that he also is flesh; yet his days shall be an hundred and twenty years." He accounts for it by their more healthful mode of living and their freedom from alcoholism and the diseases of vice, nowadays the chief cause of premature old age. He calls attention also to the fact that sour milk was in common use among the patriarchs and was esteemed by Abraham food fit to set before angels. In regard to the Mosaic dietary regulations he says:

Some of them, it is true, such as the prohibition of uncooked or partially cooked meat, are confirmed by modern knowledge. But the greater number of the Mosaic rules, as, for instance, the prohibition of the consumption as food of blood or the flesh of pigs or hares, and so forth, are in direct opposition to a modern knowledge of hygienic diet.

Metchnikoff, being a scientist, uses, of course, these reports of longevity gathered from historians and travelers merely as suggesting profitable lines of research, not as proof of any theory. Such proof can only be obtained by direct experimentation, and accordingly he has for the past fifteen years been experimenting upon himself. The Pasteur people do not belong to that class of physicians who refuse to take their own medicine. Metchnikoff still has a weak heart as the result of an intentional inoculation with recurrent fever, and some of his collaborators have inoculated themselves with the most loathsome of diseases for the purpose of testing a remedy for it. Brown-Séquard, of the Collège de France, tried, at the age of seventy-two, to rejuvenate himself by injections of animal secretions, but his hopes proved unfounded.

But the means advocated by Metchnikoff for the prevention of senescence, even though it may never fulfill his expectations, has at least the merit of being harmless, for it is merely the systematic employment of a food which has been in use by a large part of the human race from the earliest times. The object being to colonize the lactic bacilli in the lower part of the digestive tract, the best way of attaining this has yet to be worked out. The generous drinking of buttermilk or curdled milk, though this may be nutritious or otherwise beneficial, does not necessarily accomplish the object, for the bacilli may have been mostly killed off by the acidity or may be destroyed in the stomach. Taking a dose of the bacilli in a dried form, as a tablet or powder, may fail to serve the purpose, because they are in an inactive state and may not be able to secure a foot-hold for lack of suitable food, such as milk or fruit sugar. So Metchnikoff has adopted the plan of taking pure cultures of the Bulgarian and paralactic bacilli in pasteurized milk or sweetened bouillon and also in the jam and in a kind of candy prepared from cooked dates soaked in the pure cultures. He abstains from all alcoholic beverages and uses only cooked food and boiled water. His daily diet in addition to this consists of three to five ounces of meat, grains, legumes, and stewed fruit.[3]

This goes counter to the raw food advocates, but here Metchnikoff has the best of the argument. He also questions the advisability of excessive chewing as advocated by Mr. Fletcher, and cites cases where the health has been injured by the practice and the resulting disease cured by more rapid eating.[4]

As soon as Doctor Metchnikoff first made known his theory, the public, always on the lookout for a new "Elixir of Life", demanded fermented milk and the supply was immediately forthcoming, not always of a satisfactory character. Many of the cultures sold in powder or tabloids for the purpose or dispensed in drink at the soda fountains are inactive and useless, or contain other and sometimes undesirable forms of bacteria. I have found it easy enough to prepare the fermented milk in the household, where the proper cultures are to be had. All that is necessary is to sterilize the milk by heating it to the boiling point or near it and keeping it there for ten minutes; then cool quickly to 100° Fahr. and add the ferment in tabloids or powder or some of the former batch, and keep covered at this temperature for twelve hours. A vacuum bottle or fireless cooker is convenient for keeping the temperature even. The fermented milk properly prepared is somewhat thickened, slightly acid, and palatable even to those who do not like ordinary buttermilk.

Metchnikoff's views as to the value of lactic acid have met with not only the legitimate skepticism and criticism of the medical profession, but also with the usual ridicule from the press. "Who would want to live one hundred and fifty years if he had to drink sour milk three times a day?" is asked, and he is alluded to as "the modern Ponce de Leon searching for the Fountain of Immortal Youth and finding it in the Milky Whey." Of course Metchnikoff should not be held responsible for the exaggerated expectations founded upon his theories or for the fakes foisted upon the public in his name. He is indeed an original thinker and a bold experimenter, but he is not a sensationalist or a seeker for popular applause. He has never said that he expected to live one hundred and fifty years or that any one else could by following his regimen. But he does regard that period as more nearly the normal length of human life than the commonly accepted limit of sixty-five or seventy, and as possibly attainable through the advance of medical science. Though he comes of a short-lived family and all his brothers died at an age much younger than he has now attained, his health is unusually good for a man of seventy, and he is as hard-working and enterprising as ever. It is not the mere prolongation of life for which he is working, but the prolongation of the period of serviceable and enjoyable life. If he had remained in the University of Odessa, he would have been retired from his professorship on the ground of old age in 1900, the year before he published his second and greatest work, that on "Immunity in Infectious Diseases."

The title which was given to his most popular book in its English version, "The Prolongation of Life", was not of his choosing and misrepresents his aim. He regards this volume as well as its predecessor, "The Nature of Man", as "Studies in Optimistic Philosophy." They are written to show that science is not merely of use in facilitating and ameliorating the lot of human beings, but is also adequate as a guide to conduct and capable of providing it with ideals of future aspiration. In an age when, as it appears to him, religion has lost its power, and thinking men no longer have faith in immortality, he sees them turning to mysticism on the one hand and to pessimism on the other, and his purpose is to find a way out that does not involve either. As an exposition of the Religio Medici of the twentieth century, his work has great significance, and even those who look with confidence to a future life to rectify the disharmonies of this one may read with interest the opinions of one who does not hold their faith upon what may be accomplished toward perfecting the conditions of existence and may sympathize with and second his efforts at such amelioration.

Essentially his aim seems to me to be the same as that of Epicurus: to relieve mankind of its two great evils, pain and fear, the fear of the gods and the fear of death, the first to be dissipated by showing it to be imaginary and the second by welcoming death at the proper time. Like Epicurus, too, but unlike most Epicureans, Metchnikoff preaches plain living and the avoidance of luxury and dissipation of all kinds. "It would be true progress", he says, "to abandon modern cuisine and go back to the simpler dishes of our ancestors", and he objects on hygienic grounds to modern dress, dwellings, and social customs.

A society called "The Optimists" has been formed in Paris to increase the sum and intensity of human happiness and to extend the limit of active and enjoyable life. The founder is Doctor E. Dagincourt and the secretary is Mme. Languet de Bellevue, who has given fifty thousand dollars to the movement. Besides Professor Metchnikoff, the club includes Jean Finot, whose "Science of Happiness" and "Philosophy of Longevity" present similar ideals to Metchnikoff's "Optimistic Studies"; Camille Flammarion, the distinguished astronomer and author; Professor Charles Richet, who received the Nobel prize for medical discoveries in 1913; Eugene Brieux, author of "Damaged Goods" and other reform dramas; and Edmond Perrier, head of the Museum of Natural History.

Optimism Metchnikoff regards as the natural philosophy of old age when a proper appreciation of the value of life is attained and youthful pessimism outgrown.

In the normal course of life, however, the young do not show an instinctive clinging to life in any marked degree. They often risk their lives for trifling reasons and commit all sorts of indiscretions hurtful to life or health without a thought of the consequences. They may be inspired by the highest motives, but they are equally ready to fritter strength away in the gratification of the lowest appetites. Youth is the age of disinterested sacrifice, but also of indulgence in all kinds of excesses, alcoholic, sexual, and others. Youths seem to think that they will always attach the same value to life, and that between death at thirty years of age and death at sixty there is a difference only of time. As their love of life is indifferently developed, young people are often extremely exacting, the pleasure they enjoy being but moderate, whilst the suffering provoked in them by the slightest annoyance is intense. They consequently become epicureans in the lowest sense of the word, or else abandon themselves to exaggerated pessimism.—"The Nature of Man", p. 116.

Pessimism was the militant philosophy of the nineteenth century, and its effects are increasingly felt in the present world-wide tendency to suicide, individual suicide due to the failure of the instinct to live, and race suicide due to the failure to propagate. But even pessimism, harmful as it is upon humanity, may, according to Metchnikoff, have its uses:

It is pessimism which has been the first to draw up a true indictment of human nature, and if pain is to be regarded as useful in its quality of danger signal we should equally recognize that the pessimistic view of the universe is a step onward in the evolution of humanity. Without pessimism we might easily sink into a kind of contented fatalism, and end in quietism, in the manner of many religions.—"Nature of Man", p. 194.

The difference between the philosophic pessimist and the scientific optimist may be illustrated by two incidents. In 1831 Schopenhauer, in spite of his theory that life was evil and worse than nothing, fled from Berlin to Frankfort at the first outbreak of the cholera. But we recall that Metchnikoff, professed optimist and lover of life, went in 1911 to Manchuria into the center of the bubonic plague in its most virulent form in order to learn how to relieve human suffering. The difference is one between whiners and helpers.

Schopenhauer wrote that "an alteration of the atmosphere so slight that it cannot be detected by chemistry brings about cholera or yellow fever or black death." Metchnikoff's dry comment on this is: "Humanity will be fortunate if the pessimistic philosophers prove as wrong about their other grievances as they have proved about disease and medicine." And he adds that if Koch had discovered his vibrio in 1831, philosophy would have taken a different course, for Schopenhauer need not have been frightened away from Berlin, and Hegel, who died of the cholera, might have gone on with the development of his idealism.

Another paradox appears in the fact that Metchnikoff, who makes little account of altruism in his system of morality, has devoted his life to arduous and dangerous researches for the benefit of others, and, without hope of reward in another life in either the Buddhist or Christian sense, has labored assiduously to lay the foundations of a science by which posterity can profit. He regards altruism not as a permanent and indispensable virtue, but as something to be gradually got rid of, at least in its extreme forms of heroism and self-sacrifice. As this is one of the most striking and, it seems to me, most original points in his philosophy, a passage must be quoted:

As it is highly probable that with the advance of civilization the greatest evils of humanity will become lessened, and may even disappear, the sacrifices to be made will also become less. Now that there is a serum which protects against plague, there is no room for the heroism of the doctors who used to incur the greatest danger in fighting epidemics. Until lately doctors used to risk their life in treating the throats of diphtheritic patients. A young doctor who was a friend of mine, of high ability and promise, died from diphtheria contracted under these conditions. He met his death, in isolation from his friends in case of affecting them, with the utmost heroism. Now that the antidiphtheritic serum has been discovered, such heroism would be unnecessary. The advance of science has removed the occasion of such sacrifices.It is now very long since there has been opportunity for the heroism which steeled the hand of Abraham to sacrifice his only son to his religion. Human sacrifice, based on the highest morality, has become more and more rare, and will finally disappear. Rational morality, although it may admire such conduct, has no use for it. So also it may foresee a time when men will be so highly developed that instead of being delighted to take advantage of the sympathy of their fellows, they will refuse it absolutely. Neither the Kantian idea of virtue, doing good as a pure duty, nor that of Herbert Spencer, according to which men have an instinctive need to help their fellows, will be realized in the future. The ideal will rather be that of men who will be self-sufficient and who will no longer permit others to do them good.—"Prolongation of Life", p. 323.

It is now very long since there has been opportunity for the heroism which steeled the hand of Abraham to sacrifice his only son to his religion. Human sacrifice, based on the highest morality, has become more and more rare, and will finally disappear. Rational morality, although it may admire such conduct, has no use for it. So also it may foresee a time when men will be so highly developed that instead of being delighted to take advantage of the sympathy of their fellows, they will refuse it absolutely. Neither the Kantian idea of virtue, doing good as a pure duty, nor that of Herbert Spencer, according to which men have an instinctive need to help their fellows, will be realized in the future. The ideal will rather be that of men who will be self-sufficient and who will no longer permit others to do them good.—"Prolongation of Life", p. 323.

As he objects to conditions that demand sympathy and self-sacrifice from one person for another, so also he opposes any state of society that involves the sacrifice or subordination of the individual for the benefit of the community as a whole.

It is most probable that no shade of socialism will be able to solve the problem of social life with a sufficient respect for the maintenance of individual liberty. None the less the progress of human knowledge will inevitably bring about a great leveling of human fortunes. Intellectual culture will lead men to give up many things that are superfluous or even harmful, and that are still thought indispensable by most people. The conceptions that the greatest good fortune consists in the complete evolution of the normal cycle of human life and that this goal can be reached most easily by plain and sober habits will convince men of the folly of much of the luxury that now shortens human existence. Whilst the rich will choose a simpler mode of life and the poor will be able to live better, none the less, private property, acquired or inherited, may be maintained. Evolution must be gradual, and much effort and new knowledge is required. Sociology, a new-born science, must learn of biology, her older sister. Biology teaches us that in proportion that the organization becomes more complex, the consciousness of individuality develops, until a point is reached at which individuality cannot be sacrificed to the community. Amongst low creatures such as Myxomycetes and Siphonophora, the individuals disappear wholly or almost wholly in the community; but the sacrifice is small, as in these creatures the consciousness of individuality has not appeared. Social insects are in a stage intermediate between that of the lower animals and man. It is only in man that the individual has definitely acquired consciousness, and for that reason a satisfactory social organization cannot sacrifice it on pretext of the common good. To this conclusion the study of the social evolution of living beings leads me. It is plain that the study of human individuality is a necessary step in the organization of the social life of human beings.—"Prolongation of Life", p. 231.

One might think in reading "The Nature of Man" that Metchnikoff was laying the foundations of a pessimistic instead of an optimistic system of philosophy. He begins, as Schopenhauer or Von Hartmann might have done, by showing how ill adapted to his environment is that simian abortion we call man. Among the examples of marvelously perfect adaptation of structure or instinct in nature are cited Darwin's orchids and Fabre's wasps. M. Fabre seems to be indispensable to French philosophers. We have seen that Maeterlinck and Bergson get some of their finest illustrations from this "Homer of the Insects." But man is not so favored of nature as the orchids or wasps:

There can be no doubt but that the human constitution, although in many ways perfect and sublime, exhibits numerous and serious disharmonies which are the source of all our troubles. Not being so well adapted to the conditions of life as orchids are, for example, in the matter of their fertilization by the mediation of insects, or the burrowing wasps for the protection of their young, humanity resembles rather those insects the instinct of which guides them toward the flame which burns their wings.

In the first half of the nineteenth century there were published at the cost of five thousand dollars apiece eight volumes known as the Bridgewater Treatises on "The Power, Wisdom and Goodness of God as Manifested in the Creation," using as illustrations the structure of the hand, the instincts of animals, the chemistry of digestion, and other unworked sources of natural theology. The science was not bad for its time, nor was the argument altogether fallacious. But the authors overlooked one thing, namely, that Bridgewater is a game two can play at, and that it would be equally possible to fill eight other volumes by picking out a different set of facts, almost equally imposing, to prove something very different, either that there is no God or that there is a devil, either atheism or Manicheism. Metchnikoff's "Nature of Man" supplies much of the material that a devil's advocate might then have used in his Anti-Bridgewater Treatises.

But Metchnikoff, writing in the twentieth century, makes quite another use of it. He has doubtless never read the Bridgewater Treatises, nor have many of us. There is no reason to now. They have become waste paper, not because they were false, but because the whole mass of the argument against them has vanished, the half recognized and subconscious argument against theism derivable from the undeniable existence of disharmonies and imperfections in the universe. This battlefield is deserted; though the same struggle continues, it is on higher ground. This change has been wrought by the introduction of the idea of evolution. We now realize we do not live in a static universe. The theism which is founded on evolution may serenely acknowledge the discords and failures which would be fatal to the theism of the Bridgewater era. And Metchnikoff, as an atheist, is equally untroubled by the existence of misleading instincts and useless, disease-producing organs, for interpreting them in the light of evolution he escapes the slough of nineteenth century pessimism and arrives triumphantly at the goal of optimism.

At least he says he does. I cannot see that his argument leads to optimism in the strict sense of the word, although it certainly leads him to a very sane and hopeful meliorism. The weakest point in his doctrine of orthobiosis seems to me his theory of euthanasia, that at the end of the "normal cycle" of life—whatever that may be—the desire for life is replaced by an instinct for death. The evidence he adduces in support of this is very scanty and questionable. It is curious to note that it was the experiences of Metchnikoff's brother which supplied Tolstoy with the material for the most harrowing picture of the fear of death in all literature, "The Death of Ivan Ilyitch"?

In "The Prolongation of Life" Metchnikoff devotes much space to an analysis of the first and second parts of "Faust" and the life of Goethe, whom he manifestly regards as an excellent example of a complete and well-ordered life. The reader will observe that while he condemns Goethe's drinking habits because they undermined his constitution, he has, from the standpoint of a naturalist, no word of blame for his promiscuous love affairs, since these contributed to the development of his genius. This is, to say the least, a very one-sided view to take of it.

But this volume is concerned with the exposition rather than the criticism of the authors discussed, so I will conclude the chapter with a quotation which sums up his philosophy and sets forth his ideals:

In progress toward the goal, nature will have to be consulted continuously. Already, in the case of the ephemerids, nature has produced a complete cycle of normal life ending in natural death. In the problem of his own fate, man must not be content with the gifts of nature; he must direct them by his own efforts. Just as he has been able to modify the nature of animals and plants, man must attempt to modify his own constitution, so as to readjust its disharmonies.Breeders form a conception of the ideal result when they are about to attempt the production of some new variety which shall be pleasing æsthetically and of service to man. Next, they study the existing individual variations in animals and plants on which they wish to work, and from which they will select with minutest care. The ideal result must have some relation to the constitution of the organism selected. To modify the human constitution, it will be necessary, first, to frame the ideal, and thereafter to set to work with all the resources of science.If there can be formed an ideal able to unite men in a kind of religion of the future, this ideal must be founded on scientific principles. And if it be true, as has been asserted so often, that man can live by faith alone, the faith must be in the power of science.—"The Nature of Man", p. 302.

Breeders form a conception of the ideal result when they are about to attempt the production of some new variety which shall be pleasing æsthetically and of service to man. Next, they study the existing individual variations in animals and plants on which they wish to work, and from which they will select with minutest care. The ideal result must have some relation to the constitution of the organism selected. To modify the human constitution, it will be necessary, first, to frame the ideal, and thereafter to set to work with all the resources of science.

If there can be formed an ideal able to unite men in a kind of religion of the future, this ideal must be founded on scientific principles. And if it be true, as has been asserted so often, that man can live by faith alone, the faith must be in the power of science.—"The Nature of Man", p. 302.

The philosophy of Metchnikoff is given in two volumes published in this country by Putnams, "The Nature of Man" and "The Prolongation of Life." The second and later volume will perhaps better serve the purpose of the general reader, but either will give the main outlines of his theories. Both volumes are written for the medical student rather than the public, and discuss some unpleasant subjects, but not in any objectionable manner. The English translation, at least in the first editions, is clumsy and careless. These works in the original are entitled "Essais sur la nature humaine", Paris, 1903, and "Essais optimistes", Paris, 1907. The German version, "Studien über die Natur des Menschen", Leipsic, 1904, is prefaced by Ostwald. "The New Hygiene", Three Lectures on the Prevention of Infectious Diseases, prefaced by Lankester, is published by W. T. Keever & Co., Chicago.

Articles by Metchnikoff easily accessible are: "Studies in Natural Death", inHarper's Magazine, Vol. CXIV, p. 272; "The Utility of Lactic Microbes", inCentury, Vol. LXXIX, p. 53; "Old Age", in Smithsonian Report, 1904.

A criticism of Metchnikoff's individualism from a socialistic point of view is "The Optimism of Metchnikoff", by F. Carrel, inFortnightly Review, Vol. LXXXIX, p. 51. A criticism to which Metchnikoff has made a reply in his second volume is "Morale et Biologie", by D. Parodi, inRevue philosophique,Vol. LVIII, p. 113. "Metchnikoff, philosophe" (Bibliothèque des Entretiens Idéalistes, Paris, 1911) is a pamphlet by a young Catholic, Fernand Divoire, in a style of frantic denunciation.

An interesting character sketch by A. McFarlane is to be found inMcClure's Magazine, Vol. XXV, p. 541. Two interviews with Metchnikoff by Herman Bernstein are contained inWith Master Minds(Universal Series Publishing Company New York). Sir Ray Lankester in his "Science from an Easy Chair" has a chapter on "Metchnikoff and Tolstoy."

Good articles on the theory of immunity as developed by Metchnikoff and others are: "The War Against Disease", inEdinburgh Review, October, 1910; "Paul Ehrlich: The Man and His Work", by Marguerite Marks, inMcClure's Magazine, 1911, p. 184; "Natural Resistance to Disease", by Dr. Simon Flexner, of the Rockefeller Institute, inPopular Science Monthly, July, 1909, and in Smithsonian Report, 1909; "The Struggle for Immunity", by H. S. Williams, inHarper's Magazine, December, 1911. Circular No. 171 of the Bureau of American Industry of the United States Department of Agriculture gives a description ofFermented Milksby F. A. Rogers.

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