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.