Major Prophets of To-Day

by Edwin E. Slosson

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.