PART IV

SHOULD WE TRY TO PROLONG HUMAN LIFE?

I

THE BENEFIT TO HUMANITY

Complaints of the shortness of our life—Theory of

“medical selection” as a cause of degeneration of the

race—Utility of prolonging human life

Although the duration of the life of man is one of the longest amongst

mammals, men find it too short. From the remotest times the shortness

of life has been complained of, and there have been many attempts to

prolong it. Man has not been satisfied with a duration of life notably

greater than that of his nearest relatives, and has wished to live at

least as long as reptiles.

In antiquity, Hippocrates and Aristotle thought that human life was too

short, and Theophrastus, although he died at an advanced age (he lived

probably seventy-five years) lamented when he was dying “that nature

had given to deer and to crows a life so long and so useless, and to

man only one that was often very short.”[105]

Seneca (_De brevitate vitæ_) and later, in the 18th century, Haller,

strove in vain against such complaints, which have lasted until our own

days. Whilst animals have no more than an instinctive fear of danger,

and cling to life without knowing what death is, men have acquired an

exact idea of death, and their knowledge increases their desire to live.

Ought we to listen to the cry of humanity that life is too short and

that it would be well to prolong it? Would it really be for the good

of the human race to extend the duration of the life of man beyond its

present limits? Already it is complained that the burden of supporting

old people is too heavy, and statesmen are perturbed by the enormous

expense which will be entailed by State support of the aged. In

France, in a population of about 38 millions, there are two millions

(1,912,153) who have reached the age of 70, that is to say, about five

per cent. of the total. The support of these old people absorbs a

sum of nearly £6,000,000 per annum.[106] However generous may be the

views of the members of the French Parliament, many of them hesitate

at the idea of so great a burden. Without doubt, men say, the cost of

maintaining the aged will become still heavier if the duration of life

is to be prolonged. If old people are to live longer, the resources of

the young will be reduced.

If the question were merely one of prolonging the life of old people

without modifying old age itself, such considerations would be

justified. It must be understood, however, that the prolongation of

life would be associated with the preservation of intelligence and

of the power to work. In the earlier parts of this book I have given

many examples which show the possibility of useful work being done

by persons of advanced years. When we have reduced or abolished such

causes of precocious senility as intemperance and disease, it will no

longer be necessary to give pensions at the age of sixty or seventy

years. The cost of supporting the old, instead of increasing, will

diminish progressively.

If attainment of the normal duration of life, which is much greater

than the average life to-day, were to overpopulate the earth, a very

remote possibility, this could be remedied by lowering the birth-rate.

Even at the present time, while the earth is far from being too quickly

peopled, artificial limitation of the birth-rate takes place perhaps to

an unnecessary extent.

It has long been a charge against medicine and hygiene that they tend

to weaken the human race. By scientific means unhealthy people, or

those with inherited blemishes, have been preserved so that they can

give birth to weak offspring. If natural selection were allowed free

play, such individuals would perish and make room for others, stronger

and better able to live. Haeckel has given the name “medical selection”

to this process under which humanity degenerates because of the

influence of medical science.

It is clear that a valuable existence of great service to humanity is

compatible with a feeble constitution and precarious health. Amongst

tuberculous people, those with inherited or acquired syphilis, and

those with a constitution unbalanced in other ways, that is to say,

amongst so-called degenerates, there have been individuals who have had

a large share in the advance of the human race. I need only instance

the names of Fresnel, Leopardi, Weber, Schumann and Chopin. It does

not follow that we ought to cherish diseases and leave to natural

selection the duty of preserving the individuals which can resist them.

On the other hand, it is indispensable to try to blot out the diseases

themselves, and, in particular, the evils of old age, by the methods

of hygiene and therapeutics. The theory of medical selection must be

given up as contrary to the good of the human race. We must use all

our endeavours to allow men to complete their normal course of life,

and to make it possible for old men to play their parts as advisers and

judges, endowed with their long experience of life.

To the question propounded at the beginning of this section of my book,

I can make only one answer: Yes, it is useful to prolong human life.

II

SUGGESTIONS FOR THE PROLONGATION OF LIFE

Ancient methods of prolonging human life—Gerokomy—The

“immortality draught” of the Taoists—Brown-Séquard’s

method—The spermine of Poehl—Dr. Weber’s

precepts—Increased duration of life in historical

times—Hygienic maxims—Decrease in cutaneous cancer

Men of all times have attempted all manner of devices to bring about an

increase of years, although they have not considered the problem in its

general bearing.

In Biblical times it was believed that contact with young girls would

rejuvenate and prolong the life of feeble old men. In the first Book of

Kings it is related as follows:—

“Now King David was old and stricken in years; and they covered him

with clothes, but he gat no heat.

“Wherefore his servants said unto him, Let there be sought for my Lord

the king a young virgin; let her stand before the king and let her

cherish him, and let her lie in thy bosom, that my lord the king may

get heat” (Kings I., chap. i.).

This device, afterwards called _gerokomy_, was employed by the Greeks

and Romans, and has had followers in modern times. Boerhave, the

famous Dutch physician (1668-1738), “recommended an old burgomaster of

Amsterdam to lie between two young girls, assuring him that he would

thus recover strength and spirits.” After quoting this, Hufeland, the

well-known author of “Macrobiotique” in the eighteenth century, made

the following reflection:—“If it be remembered how the exhalations

from newly opened animals stimulate paralysed limbs, and how the

application of living animals soothes a violent pain, we cannot refuse

our approval to the method.”[107]

Cohausen, a doctor of the eighteenth century, published a treatise on

a Roman, Hermippus, who had died aged a hundred and fifteen years. He

had been a master in a school for young girls, and his life, passed in

their midst, was greatly prolonged. “Accordingly,” commented Hufeland

(p. 6), “he gives the excellent advice to breathe the air of young

girls night and morning, and gives his assurance that by so doing the

vital forces will be strengthened and preserved, as adepts know well

that the breath of young girls contains the vital principle in all its

purity.”

In the Eastern half of the world equal ingenuity was exercised in

the attempt to rejuvenate the body and renew the forces of man. The

successors of Lao-Tsé searched for a beverage that would confer

immortality and have recounted extraordinary matters concerning it.

The Emperor of China, Chi-Hoang-Ti (221-209 B.C.), displayed extreme

friendliness to the Taoists, believing that these had the secret of

long life and immortality. In his reign, Su-Chi, a Taoist magician,

persuaded him that eastwards of China there lay fortunate islands

inhabited by genii whose pleasure it was to give their guests to

drink of a beverage conferring immortality. Chi-Hoang-Ti was so

delighted with the news that he equipped an expedition to discover the

islands.[108]

Later on, in the dynasty of the Tchengs (618-907), when Taoism

had again become a religion in favour at court, efforts were made

to obtain imperial patronage for the draught of immortality, and

magicians were in high favour. The Taoist writers called this drink

_Tan_ or _Kin-Tan_, the “golden elixir.” According to Mayers, the

chief ingredients of this marvellous compound were “cinnabar, the

red sulphate of mercury, and a red salt of arsenic, potassium and

mother-of-pearl. The preparation of it required nine months, and it

passed through nine changes. One who had drunk of it was changed to a

crane, and in this form could ascend to the dwellings of the genii,

there to abide with them.”[109]

The Taoists represent their saints, in the shade of willows, seeking

the elixir of life, and in Chinese Buddhist temples there are placed

votive cakes shaped like the tortoise, a sacred animal and the symbol

of long life. Worshippers let stones of divination fall on these cakes

and so ascertained if their lives were to be prolonged, promising for

each subsequent year as many cakes as the divinity might demand.

The mysticism of the East reached Europe in the Middle Ages, and then,

and even in modern times, drugs were used to prolong life. Cagliostro,

the celebrated quack of the eighteenth century, boasted that he had

discovered an elixir of life by the use of which he had survived for

many thousand years.

There still exists, in some modern pharmacopœias, an “elixir ad

longam vitam” compounded of aloes and other purgatives. Analogous

preparations are known, such as the “vital essence of Augsburg” which

is a mixture of purgatives and resins.

Serious physicians have rejected such preparations of the quacks.

They have abandoned the search for a specific, and, in their efforts

to prolong human life, have relied on common rules of hygiene, such

as cleanliness, exercise, fresh air, and general sobriety. In our own

days, Brown-Séquard is an isolated instance of a seeker for a specific

against senescence. This distinguished physiologist, setting out from

the view that the weakness of old men is due partly to diminution of

the secretions of the testes, hoped to find a remedy in the employment

of subcutaneous injections of emulsions of the testes of animals

(dogs and guinea-pigs). Brown-Séquard,[110] then aged 72 years, gave

himself several such injections, and declared that he found himself

reinforced and rejuvenated. Since then, numbers of persons have

undergone the treatment which for a time was in vogue. The observations

of physicians, made on old men and sick persons, have not justified the

hopes which were entertained of the mode of treatment. Fürbringer,[111]

in particular, working in Germany, has discredited the injections of

Brown-Séquard. However, instead of following exactly the original

prescription, Fürbringer employed a testicular emulsion which had

been previously raised to the boiling-point. Brown-Séquard’s method

has not resisted scientific investigation, and although it is still

occasionally employed in France, it has been given up in many countries.

Brown-Séquard laid stress on the efficacy of emulsions of testis

as opposed to chemical substances prepared from the gland. Other

scientific men, on the other hand, have attached value to such

substances and in particular to an organic alkali the salt of which is

known as spermine. That salt, made by Poehl of St. Petersburg, has been

largely used. Several observers declare that its employment, injected

in solution or even absorbed directly as a powder, has been followed by

a strengthening of bodily power enfeebled by age or labour.

As I have no personal experience of spermine, I shall quote from

Professor Poehl[112] some indications of its efficacy. Several

physicians (Drs. Maximovitch, Bukojemsky, Krieger and Postoeff) have

given injections of spermine to enfeebled old men who had lost appetite

and sleep, and have noted improvement lasting for months. From the

instances given, I have selected that of an old lady of ninety-five

years, afflicted with severe sclerosis of the arteries, with no

appetite, a bad digestion and constipation. This patient had complained

for several years of sacral pains, and moreover was nearly quite deaf

and suffered from periodic attacks of malarial fever. The injections of

spermine, given for a period of fifteen months, restored the old lady

to such an extent that she recovered her power of hearing and felt the

sacral pains only slightly and after a long walk. Her general condition

was highly satisfactory.

Spermine, as it has been used medically, is prepared not only from the

testes of animals but from the prostate gland, ovary, pancreas, thyroid

gland and spleen. The substance is not specially associated with

spermatozoa but has a wide distribution in the mammalian body.

In the medical treatment of the evils of old age, testicular emulsions

or spermine have not been so favoured as general hygienic measures. Dr.

Weber,[113] a London medical man, has recently summarised more general

measures, and his evidence is the more important as he has been able

to test the efficacy of his precepts in his own case. Dr. Weber is 83

years old, and in his practice has cared for many other old men.

The following are the precepts which Dr. Weber formulated: All the

organs must be preserved in a condition of vigour. It is necessary to

recognise and subdue any morbid tendencies whether these be hereditary

or have been acquired during life. It is necessary to be moderate in

food and drink, and in all other physical pleasures. The air should

be pure in the dwelling and in the vicinity. It is necessary to take

exercise daily, whatever be the weather. In many cases the respiratory

movements must be specially exercised, and exercise on level ground and

up-hill should be taken. The persons should go to bed early and rise

early, and not sleep for more than six or seven hours. A bath should

be taken daily and the skin should be well rubbed, the water used

being hot or cold, according to taste. Sometimes it is advantageous

to use hot and cold water. Regular work and mental occupation are

indispensable. It is useful to stimulate the enjoyment of life so

that the mind may be tranquil and full of hope. On the other hand,

the passions must be controlled and the nervous sensations of grief

avoided. Finally, there must be a resolute intention to preserve the

health, to avoid alcohol and other stimulants as well as narcotics and

soothing drugs.

By following his own precepts, Dr. Weber has enjoyed a vigorous and

happy old age. A Mde. Nausenne, who died on March 12th, 1756, at the

age of 125 years, in the Dinay Infirmary (Côtes-du-Nord) explained the

secret of her still greater longevity as follows: “Extreme sobriety, no

worry, body and mind quite calm” (Chemin, _op. cit._, p. 101).

Hygienic measures have been the most successful in prolonging life and

in lessening the ills of old age.

Although until quite recently hygiene has rested upon a very small

number of scientifically established facts, and although its precepts

have not been followed rigidly, none the less it has already succeeded

in increasing the duration of human life. This becomes evident if we

compare the mortality tables of the present day with those of the past.

There is reason to state definitely that the mortality in civilised

countries has decreased on the whole in the last one or two centuries.

I have taken some facts regarding this from the valuable monograph

of M. Westergaard.[114] That author came to the conclusion that the

mortality rate in the 19th century in civilised countries was “much

lower than in most earlier centuries.” This diminution has been chiefly

in infantile mortality. According to Mallet, the mortality rate of

infants in the first year of their life was, in Geneva, 26 per cent.

in the 16th century, and fell gradually to 16-1/2 per cent. at the

beginning of the 19th century. A similar change has been reported from

Berlin, Holland, Denmark and other places. However, it is not only very

young infants that have shown a diminution in the death-rate. The life

of old people has been prolonged to an extent equally remarkable. The

following are some of the facts which support this statement. Whilst

the old Protestant clergymen of Denmark at ages varying from 74-1/2 to

89-1/2 years had a mortality rate of 22 per cent. in the second half

of the 18th century, the rate had sunk to 16·4 per cent. by the middle

of the 19th century. This is not an isolated fact. The old clergymen

of England (65 to 95 years) have also come to live longer, because

in the 18th century the mortality rate was 11·5 per cent. and in the

19th century (1800-1860) only 10·8 per cent. There has been a similar

decrease in the mortality rate in the members of both sexes of the

Royal Houses of Europe (Westergaard, p. 284).

From 1841 to 1850, in England and Wales 162·81 individuals out of every

thousand of both sexes died annually, but the corresponding figure for

the period 1881 to 1890 was decreased to 153·67 per thousand.

Westergaard (p. 296) has displayed in a most useful table the mortality

in the chief countries of Europe and in the State of Massachusetts, in

two periods of time. In the case of old persons from 70 to 75 years,

there has been a constant decrease in the death-rate, without any

exceptions. The exact statistics collected by Pension Bureaus and Life

Assurance Companies exhibit the same general tendency.

It cannot be disputed then that there has been a general increase

in the duration of life, and that old people live longer at the

present time than in former ages. This fact, however, cannot be taken

absolutely, and it is still possible that in particular cases there may

have been more centenarians hitherto than at present.

The prolongation of life which has come to pass in recent centuries

must certainly be attributed to the advance of hygiene. The general

measures for the preservation of health, although they were not

specially directed to old people, have had an effect of increasing

their longevity. As in the 18th century and for the greater part of

the 19th, the science of hygiene was in a very rudimentary condition,

we may well believe that improvement in cleanliness and in the general

conditions have contributed largely to the prolongation of life. It is

now a long time since Liebig said that the amount of soap used could

be taken as a measure of the degree of civilisation of a people. As

a matter of fact, cleanliness of the body brought about in the most

simple way, by washing with soap, has had a most important effect

in lessening disease and mortality from disease. In this connection,

the fact recently published by Prof. Czerny,[115] a well-known German

surgeon, has a special interest. Although cancer, the special scourge

of old age, has increased in recent times, one form of the disease,

cancer of the skin, has diminished notably. “Cancers of the skin,”

Prof. Czerny says, “are met with almost exclusively on uncovered

regions of the body, or on parts accessible to the hands. They develop

especially where the susceptibility is increased by ulcers or scars

which are easily soiled. And so it happens that in the classes where

care is taken as to cleanliness cancer of the skin is very rare and

certainly much more rare than it used to be.”

M. Westergaard thinks that vaccination against small-pox has been of

considerable importance in lowering the death-rate in the 19th century.

This, however, can have had little effect on the duration of life in

old people, as deaths due to small-pox in the old are excessively

rare. For instance, in the second half of the 18th century, that is

to say before the introduction of Jenner’s method, the mortality from

small-pox at Berlin was 9·8 per cent. of all the deaths, but of these

only 0·6 per cent. were cases of persons more than fifteen years old.

The rest, that is to say, 99·3 per cent. fell on children under that

age. It may be supposed that most of the old people at that time were

already protected by previous attacks of small-pox, contracted when

they were young.

If hygiene were able to prolong life when it was little developed, as

was the case until recently, we may well believe that, with our greater

knowledge of to-day, a much better result will be obtained.

III

DISEASES THAT SHORTEN LIFE

Measures against infectious diseases as aiding in the

prolongation of life—Prevention of syphilis—Attempts to

prepare serums which could strengthen the higher elements

of the organism

Attacks of infectious diseases incurred during life frequently shorten

its duration and it has been observed that most centenarians have

enjoyed good health throughout their lives. Syphilis is the most

important of these diseases. It is not really a cause of death itself,

but it predisposes the organism to the attacks of other diseases,

amongst the latter being some particularly fatal to old people,

such as diseases of the heart and blood-vessels (angina pectoris

and aneurism of the aorta) and some malignant tumours, especially

cancer of the tongue and of the mouth. To lengthen human life, it

is a fundamental necessity to avoid infection by syphilis. To reach

this result everything must be done to spread medical knowledge about

such diseases. It is absolutely necessary to overcome the deeply

rooted prejudice in favour of concealing everything relating to

sexual matters. Complete information should be widely spread as to

the means of protecting humanity against this awful scourge. It has

now been possible to apply experimental methods to the investigation

of this disease, and science has obtained a series of results of the

highest practical utility. Prof. Neisser of Breslau, one of the most

distinguished of modern venereal physicians, has summed up the present

state of knowledge of these matters in the following lines.[116] “It is

our duty as medical men,” he says, “to recommend strongly as a means of

disinfection in all possible cases of contagion the calomel ointment

which Metchnikoff and Roux have advised.” It is to be hoped that future

generations, by following this advice, will see an enormous diminution

in the number of cases of syphilis.

Syphilis, however, although a very important factor, is not alone

in shortening the life of man. A very large number of persons die

prematurely although they have not contracted that disease. We do not

know the duration of human life before the arrival of syphilis in

Europe, but there is no reason to think that it was very different

from what it is to-day. We must, therefore, try to prevent as many

infectious diseases as possible, and recent advances in medicine

have made this task much less difficult. Pneumonia, it is true, the

most common infectious disease amongst the old, cannot yet be easily

avoided. All the anti-pneumonic serums which have hitherto been

prepared have turned out to have little efficacy; but there is no

reason to give up the hope that this problem will yet be solved.

Diseases of the heart, which are common in extreme old age, are

particularly difficult to avoid, because in most cases we do not know

sufficiently well their primary causes. In so far as they depend upon

intemperance or infectious diseases such as syphilis, they can be

avoided by the employment of suitable measures.

As the higher elements of the body in old people become weaker and are

devoured by the macrophags, it seems probable that the destruction or

deterioration of these voracious cells would tend to the prolongation

of life. However, as the macrophags are indispensable in the struggle

against the microbes of infectious diseases, and particularly of

chronic disease, such as tuberculosis, it is necessary to preserve

them. We must turn rather to the idea of a remedy which could

strengthen the higher elements and make them a less ready prey to the

macrophags.

In the “Nature of Man” (Chap. III.) in discussing the simian origin

of mankind, I touched on the existence of animal serums that have the

power of dissolving the blood corpuscles of other species of animals.

There is now, in biological science, a new chapter upon such serums,

which have been called cytotoxic serums because they are able to poison

the cells of organs.

The blood and blood serum of some animals act as poisons when they

are introduced into an organism. Eels and snakes, even non-poisonous

snakes, are cases in point. A small quantity of the blood of a snake,

an adder for instance, injected into a mammal (rabbit, guinea-pig, or

mouse) soon brings about death. The blood of some mammals is poisonous

to other mammals, although in a lesser degree than that of snakes. The

dog is specially notable from the fact that its blood is poisonous to

other mammals, whilst, on the other hand, the blood and blood serum

of the sheep, goat, and horse have generally little effect on other

animals and on man. It is for this reason that these animals, and

particularly the horse, are used in the preparation of the serums

employed in medicine.

Now, these harmless serums become poisonous when they have been taken

from animals which have been first treated with the blood or the

organs of other species of animals. For instance, the blood serum of

a sheep which has been treated with the blood of a rabbit becomes

poisonous because it has acquired the power of dissolving the red blood

corpuscles of the rabbit. It is a poison in the case of the rabbit,

but is harmless to most other animals. The injection of the rabbit’s

blood into the sheep has conferred on the sheep a new property which

comes into operation only with regard to the red blood corpuscles

of the rabbit. We have here to do with something analogous to what

has been observed in the cases of serums used to arrest infectious

disease. When the bacilli of diphtheria, or their products, have been

injected into horses, there is produced an anti-diphtheric serum,

capable of curing diphtheria, but powerless against tetanus or plague.

After M. J. M. Bordet of the Pasteur Institute had made his discovery

of serums that had acquired the power of dissolving the red blood

corpuscles of other animals, the attempt was made to prepare similar

serums directed against all the other elements of the body, such as

white blood corpuscles, renal and nervous cells. In the course of

these investigations it was proved to be necessary to employ a certain

dose of the serum in order to obtain the poisonous result. If smaller

quantities of the poisonous dose were used, the reverse effect was

produced. Thus a serum, strong doses of which dissolved the red blood

corpuscles and so made them less numerous in the blood, increased the

number of these when given in very small doses.

M. Cantacuzène was the first to establish this fact in the case of

the rabbit, whilst M. Besredka and I myself did it in the case of

man.[117] Since then M. Bélonovsky of Cronstadt has confirmed the

result on anæmic patients, treating them with small quantities of

serum. He has been able to produce in them an increase in the number

of the red blood corpuscles, and in the quantity of the red colouring

matter (hæmoglobin) in the blood. Later on M. André[118] devoted much

attention to this matter at Lyons. He prepared a serum by injecting

human blood into animals and made use of it in the case of several

persons who suffered from anæmia from different causes. In the case

of patients, the anæmic condition of which had hitherto remained

stationary, Dr. André found a sudden increase in the number of red

corpuscles after injecting small doses of the serum. M. Besredka,

in the case of laboratory animals, increased the number of white

corpuscles by injecting them with a small quantity of a serum, strong

doses of which destroyed these cells.

These facts are only a special case of the general rule that small

doses of poisons increase the activity of the elements that are killed

by large doses. In order to increase the activity of the heart, medical

men give successfully small doses of cardiac poisons such as digitalis.

As a commercial process, the activity of yeasts is increased by

submitting them to weak doses of substances (fluoride of sodium) which,

given in larger quantities, would kill them.

My general conclusion from these facts is that it is logical to lay

down the principle that the higher elements of our body could be

strengthened by subjecting them to the action of small doses of the

appropriate cytotoxic serums. There is, however, much difficulty in

putting this into practice. It is quite easy to obtain human blood

to inject into animals with the object of preparing a serum which

can increase the number of red corpuscles. On the other hand, it is

extremely difficult to get human bodies sufficiently fresh to use them

for a practical purpose. According to law, _post mortem_ examinations

can be made only after an interval of time in course of which the

tissues have changed; besides, the organs obtained in this way are

frequently affected by injuries or diseases militating against their

use. Even in Paris, with its three million inhabitants, it is extremely

rare that there is a good opportunity for the preparation of human

cytotoxic serums. In two or three years, during which Dr. Weinberg has

collected the organs from human bodies fairly fresh, he has been unable

to obtain sufficiently active serums.

The best results have been obtained from new-born infants which have

been killed by some accident in the process of child-birth, as in them

the organs are in a normal state. However, owing to the advance in

the practice of obstetrics, such accidents, already infrequent, are

becoming extremely rare. In such conditions we may have to wait long

before getting a positive result, unless the future will find some

method of obtaining the necessary materials for this difficult and

interesting purpose.

As it is so difficult to prepare a remedy which can strengthen the

weakened higher elements of the body, it may be easier to find a means

of preventing the weakening which interferes so much with our desire to

live long. As the products of microbes are the most active agents in

deteriorating our tissues, we must look towards them for the solution

of the problem.

IV

INTESTINAL PUTREFACTION SHORTENS LIFE

Uselessness of the large intestine in man—Case of

a woman whose large intestine was inactive for six

months—Another case where the greater part of the

large intestine was completely shut off—Attempts to

disinfect the contents of the large intestine—Prolonged

mastication as a means of preventing intestinal

putrefaction

The general measures of hygiene directed against infectious diseases

play a part in prolonging the lives of old people, but, in addition to

the microbes which invade the body from outside, there is a rich source

of harm in the microbes which inhabit the body. The most important of

these belong to the intestinal flora, which is abundant and varied.

The intestinal microbes are most numerous in the large intestine. This

organ, which is useful to mammals the food of which consists of rough

bulky vegetable matter, and which require a large reservoir for the

waste of the process of digestion, is certainly useless in the case

of man.[119] In the “Nature of Man” I have dealt with this question

at length, as it was an important example of what I regard as the

disharmonies of the human constitution. A case upon which I have always

laid great stress is that of a woman who lived for thirty-seven years,

although her large intestine was atrophied and inactive, as this seems

to be a remarkable proof of the uselessness of the organ in the human

body. The small size or complete absence of the large intestine in

many vertebrates confirms my conclusion. None the less, some of my

critics think that my argument is incomplete. To strengthen it, I may

call their attention to a medical observation which is as valuable as

if it had been an experiment. It relates to a woman, sixty-two years

old, a patient of Prof. Kocher at Berne. She had been suffering from a

strangulated hernia associated with gangrene of part of the intestine,

and had to be operated upon suddenly.

The gangrenous portion of the ileum having been removed, the healthy

part was implanted in the skin so as to form an artificial aperture

through which waste matter from the food passed to the exterior

without traversing the large intestine. Although the patient was old

and seriously ill, the operation, performed by M. Tavel, was quite

successful. Six months later, in a new operation, the small intestine

was rejoined to the large intestine so that the fæces were again able

to pass to the exterior by the natural channel. In this case, then, the

large intestine was thrown out of use for half a year, not only without

injury to the general health, but with the result that the patient was

completely cured and gained in weight. MM. Macfadyen, Nencki, and Mde.

Sieber[120] studied the digestive processes in the small intestine

and the nutritive metabolism, and determined that these were active

and healthy, the absence of intestinal putrefaction, that evil of the

constitution, being specially favourable.

[Illustration: FIG. 19.—Diagram of the lower bowel in a female patient.

_A.C.N._, Artificial anus: _A.S._, Insertion of the ileum to the colon.

(After M. Mauclaire.)]

[Illustration: FIG. 20.—Diagram of the lower bowel, after a third

operation, on the case in Fig. 19.

(After M. Mauclaire.)]

In six months of non-action, the part played by an organ can be

satisfactorily estimated. M. Mauclaire,[121] however, has put on record

a case the history of which was longer. In 1902 he operated on a young

woman and produced an artificial anus, there being no escape of fæcal

matter by the ordinary channel. Ten months later M. Mauclaire operated

a second time and shut off a portion of the intestine. He left the

artificial anus, but cut across the lower end of the small intestine

and inserted it near the iliac end of the descending colon (Fig. 19).

For several days after the operation the fæces were passed by the

normal aperture, as the small intestine now communicated directly with

the large intestine, near the rectum. This condition, however, did not

persist, for the fæcal matter began to flow back through the excluded

portion of the large intestine, so reaching the artificial anus, and

causing inconvenience. Giving up the hope that this would cease, M.

Mauclaire performed a third operation twenty months later. He cut

across the large intestine near the point where the small intestine

had been artificially led into it (Fig. 20), so dividing the digestive

tube into two parts, one of which remained in communication with the

natural anus, whilst the other, consisting of nearly the whole of

the large intestine, communicated with the exterior by the artificial

anus. In the new state of affairs, the food refuse passed directly

into the terminal portion of the large intestine, and thence, by way

of the rectum, to the exterior through the normal anus without being

able to pass up the large intestine towards the artificial anus. In

this last operation about a yard of the small intestine and the greater

part of the large intestine, the cæcum, and ascending, transverse and

descending colons were removed from activity.

By the kindness of M. Mauclaire, I have been able to watch his patient

during the last four years. I satisfied myself that after the supposed

exclusion of the large intestine, food dejecta ascended the colon and

emerged by the artificial anus. There was such an accumulation of

waste in the large intestine that fragments did not emerge until three

weeks after the meal of which they had formed part. It was only after

the final operation, that in which the large intestine was separated,

that the dejecta escaped only by the natural anus, whilst a little

mucus containing microbes was passed through the artificial aperture.

Even three years after the operation, mucus continued to escape by the

latter aperture, it being shown thus that after the large intestine had

ceased to be a channel for the fæces, its walls continued to secrete

although otherwise it had lost its function completely. Nevertheless

the condition of this patient improved and she lived perfectly well

without a functional large intestine. She takes food well but has to go

to stool three or four times a day and has a tendency to diarrhœa.

The excreta are smooth and often nearly liquid, especially after fruit

has been eaten.

The case I have been describing, and which I am still keeping under

observation, demonstrates once more the uselessness of the human large

intestine; it should convert the most sceptical critic. But it also

shows that the suppression of nearly the entire large intestine for

several years does not completely get rid of the intestinal flora. Even

without this evidence, however, I do not suggest that removal of the

large intestine can be thought of as a means to prevent the pernicious

effect of the intestinal flora.

Is it possible, without operative interference, to take direct action

against the intestinal flora by the use of antiseptics? Consideration

of this is already ancient history. When the theory that the intestine

was a source of auto-intoxication was propounded, M. Bouchard[122] made

the attempt to cure such cases by disinfecting the digestive tube with

[Greek: b]-naphthol. He found, however, that that antiseptic, like

many others, not only did not completely disinfect the intestine but

sometimes had a harmful effect on the body.

M. Stern[123] has shown, in an elaborate memoir, that such antiseptics

as calomel, salol, [Greek: b]-naphthol, naphthaline, and camphor, when

administered in quantities compatible with health, do not disinfect

the digestive tube at all. More recently M. Strasburger[124] has shown

that when naphthaline has been given in quantities sufficient to impart

its odour to the fæces, the intestinal microbes, so far from being

diminished, are even increased in numbers. On the other hand, after

meals consisting of milk to which there has been added an antiseptic

in the proportion of a quarter of a gram to the litre, the intestinal

microbes are really reduced in number. Strasburger obtained his best

results with tanocol. Two persons who used, according to this method,

three to six grams of tanacol per day, displayed a notable reduction in

quantity of the intestinal flora.

Strasburger’s conclusion was that “the attempt to destroy the

intestinal microbes by the use of chemical agents has little chance of

success.” It cannot be denied that under special circumstances it is

possible to decrease the number of microbes, especially in the small

intestine. But this result is small and may be followed by the contrary

effect, for the natural means of defence of the intestine against

microbes are weakened, and the intestine itself may be harmed more than

the microbes.

Strasburger, moreover, is no convinced advocate of the use of

purgatives. The diminution of the sulpho-conjugate ethers in the

urine, which certainly may follow the use of purgatives, does not

necessarily indicate reduced putrefaction in the intestine, but may

point only to a lessened absorption of the bacterial products. Such an

interpretation is supported by an observed fact; in the case of a dog

belonging to Strasburger, which had a fistula of the small intestine,

the diarrhœa induced by calomel was accompanied by an indubitable

increase in the total quantity of intestinal microbes.

Strasburger thinks that the most favourable results can be obtained

by aiding the intestine in the discharge of its normal function. If

it can be brought to digest the food more completely, there is the

less pabulum left for the microbes. A similar result can be reached by

lowering the amount of food taken, and to this course the beneficial

effects of starvation in acute diseases of the intestine may be

attributed.

The general conclusion, reached after many experiments on the

disinfection of the intestine, is unfavourable. Very little is to be

expected from the method. None the less I cannot regard the matter

as definitely settled. Cohendy has investigated the effect on the

intestinal flora of thymol which was administered in several cases with

the object of destroying parasites. From nine to twelve grammes of

thymol were administered to each patient in the space of three days,

and there was a notable antiseptic effect, Cohendy believing that the

quantity of microbes had been reduced to a thirteenth.

Such facts prove only that the antiseptic treatment is available

up to a certain point. To attain the results, however, such large

quantities must be used that the treatment can be applied only in

special cases and at long intervals. More use can be made of simple

purgatives which do not kill the microbes but eliminate them by the

normal channel. It has been urged repeatedly that calomel, which is

often used as a purgative, acts also as an intestinal antiseptic;

but it is probable that its influence in reducing the intestinal

flora is merely mechanical. It has been shown that calomel, like

some other purgatives, lessens intestinal putrefaction, the evidence

being the decrease in the sulpho-conjugate ethers in the urine. But

although the diarrhœa induced by purgatives generally has such a

result, spontaneous diarrhœas such as those of typhoid fever and of

intestinal tuberculosis are associated with increased putrefaction.[125]

It is clear, however these matters may be settled, that regular

activity of the bowels, increased by the occasional use of purgatives,

must diminish the formation of intestinal poisons, and therefore also

the damage done by these to the higher elements of the body.

When I asked the relatives of Mde. Robineau if they could tell me of

any special circumstance which in their opinion had contributed to

the extreme duration of the life of this old lady, they replied as

follows:—“We are convinced that a slight bodily derangement, present

for the last fifty years, has tended to prolong the life of the old

lady. It cannot be said that she has suffered from diarrhœa, but

she has been often subject to frequent calls of nature.” It was most

remarkable that the old lady showed no traces of sclerosis of the

arteries. I may mention the strongly contrasting case of one of my

old colleagues to whom a natural desire to empty the bowels came only

once a week. A more frequent call was a sign of illness in his case.

Now sclerosis of the arteries appeared in so marked a form that he

died from it before he had reached the age of fifty years. This may be

added to the list of facts which point to a close association between

sclerosis of the arteries and the functions of the digestive tube.

Recently, at the suggestion of Mr. Fletcher,[126] the advantage of

eating extremely slowly has been recognised, the object being to

prepare for the utilisation of the food materials, and to prevent

intestinal putrefaction. Certainly the habit of eating quickly favours

the multiplication of microbes round about the lumps of food which have

been swallowed without sufficient mastication. It is quite harmful,

however, to chew the food too long, and to swallow it only after it

has been kept in the mouth for a considerable time. Too complete a

use of the food material causes want of tone in the intestinal wall,

from which as much harm may come as from imperfect mastication. In

America, where Fletcher’s theory took its origin, there has already

been described under the name of “Bradyfagy” a disease arising from the

habit of eating too slowly. Dr. Einhorn,[127] a well-known specialist

in the diseases of the digestive system, has found that several cases

of this disease were rapidly cured when the patients made up their

minds to eat more quickly again. Comparative physiology supplies us

with arguments against too prolonged mastication. Ruminants, which

carry out to the fullest extent Mr. Fletcher’s plan, are notable for

extreme intestinal putrefaction and for the short duration of their

lives. On the other hand, birds and reptiles, which have a very poor

mechanism for breaking up food, enjoy much longer lives.

Prolonged mastication, then, cannot be recommended as a preventative

of intestinal putrefaction any more than the surgical removal of the

large intestine or the disinfection of the digestive tube. The field

lies open for other means which may probably solve the problem more

completely and more practically.

V

LACTIC ACID AS INHIBITING INTESTINAL PUTREFACTION

The development of the intestinal flora in

man—Harmlessness of sterilised food—Means of

preventing the putrefaction of food—Lactic fermentation

and its anti-putrescent action—Experiments on

man and mice—Longevity in races which use soured

milk—Comparative study of different soured

milks—Properties of the Bulgarian _Bacillus_—Means

of preventing intestinal putrefaction with the help of

microbes

At birth the human intestine is full, but contains no microbes.

Microbes very soon appear in it, because the meconium, the contents

of the intestines of new-born children, composed of bile and cast-off

intestinal mucus cells, is an excellent culture medium for them. In the

first hours after birth, microbes begin to reach the intestine. In the

first day, before the child has taken any food whatever, there is to

be found in the meconium a varied flora, composed of several species

of microbes. Under the influence of the mother’s milk this flora is

reduced and comes to be composed almost entirely of a special microbe

described by M. Tissier and called by him _Bacillus bifidus_.

The food, therefore, has an influence on the microbes of the intestine.

If the child be fed with cow’s milk, the flora is richer in species

than in the case of a child suckled by its mother. Later on, also,

the flora varies with the food, as has been proved by MM. Macfadyen,

Nencki, and Mde. Sieber in the case of a woman with an intestinal

fistula. The dependence of the intestinal microbes on the food makes

it possible to adopt measures to modify the flora in our bodies and

to replace the harmful microbes by useful microbes. Unfortunately,

our actual knowledge of the intestinal flora is still very imperfect

because of the impossibility of finding artificial media in which it

could be grown. Notwithstanding this difficulty, however, a rational

solution of the problem must be sought.

Man, even in the savage condition, prepares his food before eating it.

He submits much of it to the action of fire, thus notably lessening the

number of microbes. Microbes enter the digestive tube in vast numbers

with raw food, and in order to lessen the number of species in the

intestines, it is important to eat only cooked food and to drink only

liquids that have been previously boiled. In that way, although we

cannot destroy all the microbes in the food, because some of them can

withstand the temperature of the boiling point of water, we can kill

the great majority of them.

It has sometimes been supposed that cooked or completely sterilised

food (that is to say food that has been subjected to a temperature of

from 248°-284° Fahr.) is harmful to the organism and that much of it

is not well digested. From this point of view protests have been made

against the feeding of infants with sterilised milk or even with boiled

milk. Although in certain cases sterilised milk is not well supported

by infants, it cannot be doubted but that boiled milk and cooked

food are generally successful. The large number of children brought

up successfully on boiled cow’s milk and the health of travellers in

arctic regions are ample proof of this. I have been told by M. Charcot

that in his voyage to the antarctic regions, he and his companions

lived entirely on sterilised food, or on cooked food such as the flesh

of seals and penguins. As they had no green food nor fresh fruit, the

only raw food that they ate was a little cheese. Living under these

conditions, all the members of the expedition enjoyed good health,

and there was no case of digestive disturbance in the whole period of

sixteen months.

It is obvious that abstaining from raw food, and so reducing largely

the entrance of new microbes, by no means causes the disappearance

of the intestinal flora already existing. We must reckon with that

and with the evil that it does by weakening the higher cells of the

tissues. As the part of the flora that does most damage consists of

microbes which cause putrefaction of the contents of the intestine and

harmful fermentations, particularly butyric fermentation, it is against

these that our efforts must be directed.

Long before the science of bacteriology was in existence, men had

turned their attention to methods of preventing putrefaction. Food,

especially if it be kept in a warm place or in a moist atmosphere, soon

begins to putrefy and to become unpleasant to the taste and dangerous

to the health. Everyone has known cases of poisoning from putrid flesh

or other food material. Foà,[128] the explorer of Central Africa, has

related that once, when they were starving, he and his men came on the

putrefying body of an elephant. The negroes rushed to lay hold of the

carrion, but Foà tried to dissuade them, explaining that to eat flesh

in such a state was as bad as taking poison. All did not listen to him,

and three negroes, who had taken pieces of the body, swallowed them

before they had been properly cooked. All three died in a few days,

with the neck and throat swollen, the tongue almost paralysed, and the

abdomen inflated.

In another case, sausages made of putrid horse flesh caused an epidemic

at Rohrsdorf, in Prussia, in 1885.[129] About forty people fell ill

after having eaten the sausages, which, according to witnesses, were

green in colour, smelt badly, and had a revolting appearance. One

person died, whilst the others recovered after cholera-like symptoms.

It is true that all putrefying food does not produce the same effect.

MM. Tissier and Martelly[130] found no digestive trouble after having

eaten food that was quite putrid. Everyone knows that the Chinese

prepare a dish particularly pleasant to gourmets by allowing eggs

to putrefy. Some decaying cheeses are harmful to the health, but

others can be eaten with impunity. The reason of this is that whilst

putrefying food may contain microbes and dangerous toxins, it does

not contain them in all cases. On the other hand, we must take into

account the different susceptibilities of people to the harmful action

of microbes and their products. Some can swallow without any evil

result a quantity of microbes which in the case of other individuals

would produce a fatal attack of cholera. Everything depends upon the

resistance offered to the microbes by the invaded organism.

Experiments on animals fed on putrefying food have also given varied

results. Some animals eat it without any harm resulting, others have

attacks of vomiting and show such a repugnance that it is impossible to

continue the experiment.

Not only flesh and other animal substances, but vegetables can undergo

putrefaction and fermentation (butyric) which make it dangerous

to eat them. Many accidents have occurred in man as the result of

deteriorated preserved fruit. Vegetables, preserved in silos to feed

cattle, sometimes go wrong. “If, for instance, rainy days come after

sunny days, so that the uncovered fodder is wetted again, the resulting

ensilage is poor and has an extremely unpleasant butyric odour, so that

the animals turn from it.” Sometimes the fodder grows black in the

silo, and acquires a special smell. “The animals will take it only in

the absence of other food; their excreta become black, and if they are

kept on such a diet for a time they waste in a marked manner.”[131]

In popular practice, the value of acids for preserving animal

and vegetable food and for preventing putrefaction has long been

recognised. Meats of all kinds, fish and vegetables have been

“marinated” with vinegar, as the acetic acid in that substance, the

product of bacteria, wards off putrefaction. If the materials which

it is desired to preserve give off acids themselves, the addition of

vinegar may be unnecessary. For this reason some animal products such

as milk, or vegetables rich in sugar become acid spontaneously and so

can be preserved. Soured milk can be made into many kinds of cheese,

and these last for longer or shorter times. Many vegetables can undergo

a natural process of souring, when they “keep” without difficulty.

Thus cabbage becomes “sauerkraut” and beetroot and cucumbers pass

into an acid state. In many countries, as for instance in Russia, the

use of acidified vegetables is of great importance in the food-supply

of the populace. Fresh fruit and vegetables cannot be obtained in the

long winters, during which the people consume large quantities of

cucumbers, melons, apples, and other fruits which have undergone an

acid fermentation in which lactic acid is the chief product. During

summer, milk, which acidifies readily, is the chief source of acid

materials for consumption. The chief beverage is “kwass,” of which

black bread is the main ingredient, and this passes through not only an

alcoholic fermentation, but an acidifying change in which lactic acid

is the most important product.

Rye bread, the chief food of the populace, is also a product of

fermentations amongst which the lactic acid fermentation is most

important, but in other kinds of bread also there is a fermentation in

which some of the sugar is transformed to lactic acid.

Soured milk, because of the lactic acid in it, can impede the

putrefaction of meat. In certain countries, accordingly, meat is

preserved in acid skimmed milk with the result that putrefaction

is prevented. Lactic acid fermentation is equally important in the

food supply of cattle. It is the chief agent that, in the process of

preserving vegetation in silos, hinders putrefaction. Finally, the same

fermentation serves in distilleries to preserve the must from which

alcohol is prepared.

This short review is in itself enough to show the great importance of

lactic fermentation as a means of stopping putrefaction and butyric

fermentation, both of which hinder the preservation of organic

substances and are capable of exciting disturbances in the organism.

As lactic fermentation serves so well to arrest putrefaction in

general, why should it not be used for the same purpose within the

digestive tube?

It is a matter of common knowledge that putrefaction and butyric

fermentation are arrested in the presence of sugar. Whereas meat

preserved without special care soon putrefies, milk in exactly the

same conditions does not putrefy, but becomes sour, the reason being

that meat is poor in sugar whereas milk contains a good deal of it.

However, the scientific explanation of this fundamental fact is

difficult. It has been shown conclusively that sugar itself cannot

prevent putrefaction. Milk, for instance, however rich in sugar it

may be, readily putrefies in certain conditions. Sugar preserves

organic matter from putrefaction only because it can readily undergo

lactic fermentation, and this fermentation is the work of the microbes

described fifty years ago by Pasteur. That great discovery proved the

part played by microbes in fermentation and founded bacteriology, a

science equally rich in theory and in practice.

I need not pause to develop the theme that the anti-putrescent action

of the lactic fermentation depends on the production of lactic acid by

microbes, because I have explained the matter at length in the tenth

chapter of the “Nature of Man.” If the lactic acid be neutralised,

the organic matter soon putrefies, notwithstanding the presence of

the lactic microbes. The most important point is as to whether lactic

fermentation really arrests intestinal putrefaction. Several sets of

observations have been made upon this matter. Dr. Herter,[132] of

New York, injected directly into the small intestine of a number of

dogs quantities of different microbes. To test the action of these on

intestinal putrefaction, he investigated the sulpho-conjugate ethers

in the urine, as he believed, in accordance with current and well

justified opinion, that these substances are the best proofs of the

existence of putrefaction. He found that whilst the introduction of

quantities of _Bacillus coli_ or _Bacillus proteus_ increased the

intestinal putrefaction, lactic bacilli notably lessened it. Herter

found a notable diminution of sulpho-conjugate ethers in the urine of

dogs which had been treated with the lactic microbes.

The experiments which Dr. M. Cohendy[133] performed upon himself during

a period of nearly six months are still more interesting.

When Dr. Cohendy had proved that much intestinal putrefaction occurred

during a period of 25 days, in which he lived on an ordinary mixed

diet, he began to take pure cultures of lactic bacillus, taken from

yahourth. In a period of 74 days, he took quantities varying from 280

to 350 grams of the culture.

Analysis of the urine during the progress of the experiment showed

that intestinal putrefaction had notably decreased whilst the lactic

bacilli were being taken, and that the diminution persisted seven weeks

after the taking of the bacilli ceased. Dr. Cohendy gives it as the

direct result of his experiment that the introduction of lactic ferment

into the intestine definitely arrests putrefaction. He obtained this

result on a diet consisting of 400 grams of soup, 150 of meat, 700 of

grain-food, 400 of green vegetables, 300 of fruits and dessert and a

litre of water. He came to the conclusion that the elimination of meat

from the diet was unnecessary, as the particular kind of lactic ferment

he employed was extremely active in inhibiting the proteolytic ferments.

Later experiments made by Dr. Cohendy showed that the lactic bacillus

became so acclimatised in the human intestine that it was to be found

there several weeks after it had been swallowed.

Dr. Pochon, assistant to Professor Combe[134] at Lausanne, has repeated

on himself the experiments of Cohendy. He took for several weeks

milk curdled with pure cultures of lactic acid microbes and obtained

“results that were quite definite as to intestinal putrefaction.”

Analysis of his urine showed that there was a marked diminution of

indol and phenol, substances which are certain indexes of intestinal

putrefaction.

In addition to such observations on lactic bacilli there is a good deal

of knowledge as to the effect of lactic acid taken in bulk. The result

of the various observations[135] shows that the acid lessens intestinal

putrefaction and lowers the quantity of sulpho-conjugate ethers in the

urine. This fact explains why favourable results follow the use of

lactic acid in many intestinal diseases such as infantile diarrhœa,

tuberculous enteritis and even Asiatic cholera. The addition of this

remedy to practical therapeutics is due chiefly to Professor Hayem.

It is employed not only in the treatment of diseases of the digestive

system (dyspepsia, enteritis and colitis), but is indicated also in

diabetes and is used locally in tuberculous ulcerations of the larynx.

As quantities up to twelve grams can be given by the mouth daily, it is

plain that the system is tolerant of this acid. It is either oxidised

in the tissues or excreted with the urine. In the case of a diabetic

woman who had taken 80 grams of lactic acid in four days, Nencki and

Sieber[136] found no traces of it in the urine. On the other hand,

Stadelmann[137] found a notable quantity of the acid in another

diabetic patient who had been taking over four grams daily.

The general interpretation of the benefits gained from the use of

lactic acid ferments is that they depend solely on the action of the

lactic acid which they produce in preventing the multiplication of

the microbes which cause putrefaction. Recent investigations made by

Dr. Bélonowsky, at the Pasteur Institute, show that a lactic ferment

isolated from yahourth and described as the Bulgarian bacillus owes

its antiseptic powers not only to lactic acid but to another substance

which it secretes. Dr. Bélonowsky has studied the effects of this

bacillus upon mice, by adding to their previously sterilised food

quantities of this lactic microbe. As control experiments he fed

other mice on food to which lactic acid had been added in quantities

corresponding to the quantity produced by the Bulgarian bacillus, or

which had been mixed with other kinds of bacilli. Another set of mice

were given normal food without the addition of either microbes or

lactic acid.

Out of these groups of mice, those which had been given the Bulgarian

bacillus thrived best and had most progeny. Their droppings showed

fewest microbes, particularly microbes of putrefaction.

The next stage in Dr. Bélonowsky’s experiments was to feed mice not

with living quantities of the Bulgarian bacillus, but with cultures

which had been sterilised by heat (120°-140° Fahr.). These mice lived

as well as those to which living cultures had been supplied, and

notably better than those supplied with pure lactic acid. It is evident

therefore that there is some other product of this bacillus which

favours life by preventing intestinal putrefaction.

Dr. Bélonowsky showed, moreover, that the Bulgarian bacillus cures a

special intestinal disease known as mouse typhus.

The experiments which I have described show that intestinal

putrefaction is to be combated not by lactic acid itself, but by the

introduction into the organism of cultures of the lactic bacilli.

The latter become acclimatised in the human digestive tube as they

find there the sugary material required for their subsistence, and by

producing disinfecting bodies benefit the organism which supports them.

From time immemorial human beings have absorbed quantities of lactic

microbes by consuming in the uncooked condition substances such as

soured milk, kephir, sauerkraut, or salted cucumbers which have

undergone lactic fermentation. By these means they have unknowingly

lessened the evil consequences of intestinal putrefaction. In the Bible

soured milk is frequently spoken of. When Abraham entertained the three

angels he set before them soured milk and sweet milk and the calf which

he had dressed (Genesis xviii. 8). In his fifth book, Moses enumerates

amongst the food which Jehovah had given his people to eat “Soured milk

of kine and goat’s milk, with fat of lambs and rams of the breed of

Bashan, and goats with the fat of kidneys” (Deut. xxxii. 14).[138]

A food known as “Leben raib,” which is a soured milk, prepared from

the milk of buffaloes, kine or goats, has been used in Egypt from

the remotest antiquity. A similar preparation known as “yahourth” is

familiar to the populations of the Balkan Peninsula. The natives of

Algiers make a kind of “leben” not identical with the Egyptian form.

Soured milk is consumed in great quantities in Russia in two forms,

“prostokwacha,” which is raw milk spontaneously coagulated and soured,

and “varenetz,” which is boiled milk soured with a yeast.

The chief food of many natives of tropical Africa consists of soured

milk. The staple diet of the Mpeseni is “a curdled milk, almost

solidified.” “Meat is eaten only on ceremonial occasions.” According

to Foà, a tribe of the Nyassa-Tanganyika plateau, like the Zulus, take

milk only in the form of a raw cheese mixed with salt and pepper.

Dr. Lima of Mossamedes, in West Africa, has told me that the natives

of many regions south of Angola live almost entirely on milk. They

employ the cream as an ointment for the skin, whilst the milk, soured

and curdled, is their staple food. M. Nogueira reported the same

circumstances nearly fifty years ago after his journey in the province

of Angola.

Just as cheeses vary in different countries, so curdled milk varies

slightly according to the nature of the flora of microbes. Taking all

the soured milks that are produced by natural processes, it may be said

that the greater number of them contain not only microbes that produce

lactic acid, but also yeasts that cause alcoholic fermentations.

Kephir, which is prepared from the milk of kine, and koumiss, which

is a product of mares’ milk, are notably alcoholic. Koumiss is the

well-known national beverage of the Kirghises, Tartars and Kulmucks,

nomads of Asiatic Russia who are famous horse breeders, whilst kephir

is the native drink of the mountaineers of the Caucasus, the Ossetes,

and some other tribes.

It has been supposed that the chief merit of kephir was that it was

more easy to digest than milk, as some of its casein is dissolved in

the process of fermentation. Kephir, in fact, was supposed to be partly

digested milk. This view has not been confirmed. Professor Hayem thinks

that the good effects of kephir are due to the presence of lactic acid

which replaces the acid of the stomach and has an antiseptic effect.

The experiments of M. Rovighi, which I spoke of in _The Nature of Man_,

have confirmed the latter fact, which now may be taken as certain. The

action of kephir in preventing intestinal putrefaction depends on the

lactic acid bacilli which it contains.

Kephir, although in some cases certainly beneficial, cannot be

recommended for the prolonged use necessary if intestinal putrefaction

is to be overcome. It is produced by combined lactic and alcoholic

fermentations, and as it contains up to one per cent. of alcohol, its

use as a food for years would involve the absorption of considerable

quantities of alcohol. The yeasts which produce it can be acclimatised

in the human digestive tract, in which, however, they are harmful, as

they are favourable to the germs of infectious diseases such as the

bacillus of typhoid fever, and the vibrio of Asiatic cholera.

Kephir has also the disadvantage that its flora varies considerably and

is not well known. There has been little success in producing it by

pure cultures as would be necessary were it to be brought into general

use. When it is prepared from a dried remnant there is the risk of

stray microbes being included, and these may bring about pernicious

fermentations. Professor Hayem prohibits its use in the case of

persons in whom food is retained for long in the stomach. “When it

is retained in the stomach, kephir goes on fermenting, and there are

developed in the contents butyric and acetic acids which aggravate the

digestive disturbances.”[139]

As it is the lactic and not the alcoholic fermentation on which the

valuable properties of kephir depend, it is correct to replace it by

soured milk that contains either no alcohol or merely the smallest

traces of it.

The fact that so many races make soured milk and use it copiously is

an excellent testimony to its usefulness. M. Nogueira has written

to me to say how much he was astonished, on revisiting after a long

period of absence the district of Mossamedes, to find the natives so

well preserved and displaying so few traces of senility. Dr. Lima has

stated that amongst the natives of the region south of Angola “many

individuals of extraordinary longevity are to be found.” Although they

are thin and withered, these old people are very active and can make

long journeys.

Mr. Wales, a lawyer at Binghampton, U.S.A., has been so good as to

make me acquainted with some extremely interesting facts taken from a

work by James Riley which is now a bibliographical rarity.[140] In the

narrative of a shipwreck of the vessel on which he made a voyage in

1815, James Riley states that the wandering Arabs of the desert live

almost wholly on the milk of camels, fresh or soured.

On this diet they enjoy excellent health, display great vigour and

reach advanced ages. Riley estimated that some of the old men must have

lived for two to three hundred years. No doubt these figures are much

too high, but it is probable that the Arabs Riley encountered lived

really unusually long.

Mr. Wales has examined Riley’s work critically, and is of the opinion

that that author was a well-informed, sagacious and conscientious

observer.

M. Grigoroff, a Bulgarian student at Geneva, has been surprised by

the number of centenarians to be found in Bulgaria, a region in which

yahourth, a soured milk, is the stable food. Some of the centenarians,

described by M. Chemin in his memoir, lived chiefly on a milk diet.

Marie Priou, for example, who died in the Haute-Garonne in 1838 at the

age of 158 years, had lived for the last ten years of her life entirely

on cheese and goat’s milk (_op. cit._ p. 100). Ambroise Jantet, a

labourer of Verdun, who died in 1751 at the age of 111 years, “ate

nothing but unleavened bread and drank nothing but skimmed milk” (p.

133). Nicole Marc, who died aged 110 years, at the chateau of Colemberg

(Pas-de-Calais), a hunch-back and cripple, “lived only on bread and

milk-food. It was only towards the end of her life and after much

persuasion that she took a little wine” (Chemin, p. 139).

I owe to the kindness of M. Simine, an engineer in the Caucasus, the

following communication, taken from the newspaper _Tiflissky Listok_,

Oct. 8th, 1904. “In the village of Sba, in the district of Gori, there

is an old Ossete woman, Thense Abalva, whose age is supposed to be

about 180 years (?). This woman is still quite capable and looks after

her household duties and sews. Although she is bent, she walks firmly

enough. Thense has never taken alcoholic liquors. She rises early in

the morning, and her chief food is barley bread and butter milk, taken

after the churning of the cream. Butter milk is a liquid containing

very many lactic microbes.

Mrs. Jenny Read, an American, has written to me that her father,

eighty-four years old, “owes his health to the curdled milk which he

has taken for the last 40 years.”

Curdled milk and the other products of milk to which I have referred

are the work of the lactic microbes which produce lactic acid at the

expense of milk sugar. As many different kinds of soured milk have been

consumed on a vast scale and have proved to be useful, it might be

supposed that any of them is suitable for regular consumption with the

object of preventing intestinal putrefaction.

From the point of view of flavour I find that soured milk, prepared

from raw milk, is much the more agreeable. However, when a food is to

be selected for consumption during a long period of time, we must keep

hygiene strictly in view. It is certain, therefore, that the Russian

“prostokwacha,” as well as any other soured raw milk, must be rejected.

Raw milk contains a large assortment of microbes, and frequently some

of these are harmful. The bacillus of bovine tuberculosis, as well

as other pernicious microbes, may be found in it. According to the

investigations of Heim[141] the vibrios of Asiatic cholera, when placed

in raw milk, survive even when the milk has become quite soured. In

similar conditions the bacillus of typhoid fever remains alive for 35

days and dies only after it has been kept for 48 days in completely

soured milk.

As raw milk nearly always contains traces of fæcal matter from the

cow, it sometimes happens that pernicious microbes are introduced from

that source, and remain alive notwithstanding the acid coagulation of

the milk. The lactic microbes certainly prevent the multiplication

of other microbes, as, for instance, those of putrefaction, but are

incapable of destroying them. Moreover, raw milk often contains fungi

(yeasts, torulas, and oïdia) the presence of which is favourable to the

development of such pernicious microbes as the cholera vibrio and the

bacillus of typhoid fever.

Prolonged consumption of raw milk increases the risk of introducing

dangerous microbes into the organism, and this possibility drives me to

recommend soured milk prepared after heating. Theoretically, it would

be best to sterilise the milk completely so that all the contained

microbes would be destroyed. This, however, requires heating the milk

to a temperature of from 226° to 248° Fahr., by which it acquires an

unpleasant flavour. On the other hand, the pasteurising of milk at a

temperature of about 140° Fahr. is not sufficient to get rid entirely

of the bacilli of tuberculosis and the spores of the butyric bacilli.

We have, therefore, to fall back on a middle course, and be content

with boiling the milk for several minutes. By so doing we certainly

kill the tubercle bacilli and the spores of some of the butyric

bacilli,[142] there being left only some butyric spores and the spores

of _Bacillus subtilis_, to destroy which a much higher temperature is

necessary.

As some kinds of soured milk, such as “varenetz,” “yahourth,” “leben,”

etc., are prepared from boiled milk, it might be supposed that

they fulfil the conditions necessary for prolonged use. A closer

examination, however, makes us reject them.

Boiled milk, to make it undergo the lactic fermentation properly,

must have added to it a prepared ferment. What is necessary is not

merely rennet, as was formerly supposed, but a number of organised

ferments, that is to say, microbes. In the preparation of these soured

milks, a leaven is employed, one of the names of which is “Maya,”

and which contains not only lactic microbes, but several others. MM.

Rist and Khoury[143] have come to the conclusion that the Egyptian

“leben” contained a flora composed of five species, three of which

are bacteria and two yeasts. The bacteria produce lactic acid and the

yeasts alcohol. Although the result is that “leben” is a nearly solid

substance, whilst kephir is a liquid, the two are closely similar.

In both cases we have to do with coincident lactic and alcoholic

fermentations, and my remarks regarding kephir apply equally well to

the Egyptian “leben.”

Through the agency of Prof. Massol of Geneva, I have obtained a

specimen of the Bulgarian “yahourth.” Working with his pupil, M.

Grigoroff, M. Massol[144] has isolated several microbes from this milk,

amongst these being a very active lactic bacillus. The same soured

milk has been studied in my laboratory by Drs. M. Cohendy[145] and

Michelson. They found in it a very powerful lactic ferment, which has

been named the Bulgarian bacillus. This was the microbe employed in the

experiments of M. Bélonowsky, to which I have already referred. More

recently, it has been carefully investigated from the chemical point of

view by MM. G. Bertrand and Weisweiler[146] at the Pasteur Institute.

It proved to be an extremely active producer of lactic acid, supplying

25 grammes per litre of milk. The other acids which this bacillus

produces, such as succinic and acetic acids, are formed only in very

small quantities (about 50 centigrams a litre). Formic acid is produced

only in traces. On the other hand, the Bulgarian bacillus forms neither

alcohol nor acetone, two frequent products of bacterial fermentation.

The bacillus also differs from other lactic ferments inasmuch as it

has no action on albuminoids (casein, etc.), nor on fats. All these

qualities make the Bulgarian bacillus much the most useful of the

microbes which can be acclimatised in the digestive tube for the

purpose of arresting putrefactions and pernicious fermentations, such

as the butyric fermentation.

As in all the known soured milks (yahourth, leben, prostokwacha,

kephir, and koumiss) the lactic bacilli are associated with a rich

flora in which pernicious microbes may be met (such as the red torula,

a microbe which predisposes to cholera and typhoid fever, which I found

in the leaven of yahourth, bought in Paris), it is necessary to work

out a method by which good curdled milk can be produced with the aid of

pure cultures of the lactic microbes.

It was the obvious course to begin with the Bulgarian bacillus, as

that is known to be the best producer of lactic acid. It coagulates

milk rapidly, giving it a strongly acid flavour, but it often also

gives a disagreeable taste of tallow. It is true that after it has been

kept for a long time in the laboratory in the form of pure cultures

in sterilised milk, the bacillus loses to a large extent its power

of saponifying fats, the taste of the curdled milk being then more

agreeable. If necessary, therefore, soured milk prepared exclusively

with the Bulgarian bacillus can be used. In practice, however, it

is useful to associate with it another lactic microbe, known as the

paralactic bacillus, as the latter, although producing less lactic acid

than the Bulgarian bacillus, does not break up the fats and gives the

curdled milk a very pleasant flavour.

As it is undesirable to absorb too much fatty matter, it is necessary

to prepare curdled milk for regular use from skimmed milk. After the

milk has been boiled and rapidly cooled, pure cultures of the lactic

microbes are sown in it, in sufficient quantities to prevent the

germination of spores already in the milk and not destroyed in the

process of boiling. The fermentation lasts a number of hours, varying

according to the temperature, and finally produces a sour curdled milk,

pleasant to the taste and active in preventing intestinal putrefaction.

This milk, taken daily in quantities of from 300 to 500 cubic

centimetres, controls the action of the intestine, and stimulates the

kidneys favourably.[147] It can therefore be recommended in many cases

of disorder of the digestive apparatus, of the kidneys, and in several

skin diseases.

The Bulgarian bacillus taken from yahourth or from soured milk,

prepared from pure cultures of lactic microbes, can live in warm

temperatures, and, as has been shown by Dr. Cohendy, is able to take

its place in the intestinal flora of man.

Soured milk, prepared according to the receipt which I have given, has

been analysed by M. Fouard, an assistant at the Pasteur Institute.

When it was ready to be taken, M. Fouard found in it about 10 grammes

of lactic acid per litre. Moreover, a large proportion (nearly

38 per cent.) of the casein had been rendered soluble during the

fermentation, which shows that its albuminous matter is prepared for

digestion much as in kephir. Of the phosphate of lime (which is the

chief mineral substance of milk) 68 per cent. was rendered soluble

during the fermentation. These facts all confirm the utility of the

soured milk prepared from pure cultures of lactic bacteria.

Those persons who, from some reason or other, cannot take milk, may

swallow the bacilli in a pure culture without milk. However, as the

microbes need sugar to produce lactic acid, it is necessary to take

with them a certain quantity of sweet food (jam, sweet-meats, and

especially beetroot).

The Bulgarian bacillus produces lactic acid not only from milk sugar,

but also from many other sugars, for instance, cane sugar, maltose,

levulose and especially glucose.

Cultures of the bacillus can be made not only in milk, but in vegetable

broths, or broths of animal peptone to which sugar has been added. The

cultures can be taken in a dry form (powders or tabloids), or in the

liquid in which the bacilli had themselves been developed.

A reader who has little knowledge of such matters may be surprised

by my recommendation to absorb large quantities of microbes, as the

general belief is that microbes are all harmful. This belief, however,

is erroneous. There are many useful microbes, amongst which the lactic

bacilli have an honourable place. Moreover, the attempt has already

been made to cure certain diseases by the administration of cultures

of bacteria. M. Brudzinsky[148] has used cultures of lactic microbes

in certain intestinal diseases of infants, whilst Dr. Tissier[149] has

used them in similar affections of infants and adults.

From the general point of view of this book, the course recommended

consists of the absorption either of soured milk prepared by a group of

lactic bacteria, or of pure cultures of the Bulgarian bacillus, but in

each case taking at the same time a certain quantity of milk sugar or

saccharose.

For more than eight years I took, as a regular part of my diet, soured

milk at first prepared from boiled milk, inoculated with a lactic

leaven. Since then, I have changed the method of preparation and have

adopted finally the pure cultures which I have been describing. I am

very well pleased with the result, and I think that my experiment

has gone on long enough to justify my view. Several of my friends,

some of whom suffered from maladies of the intestine or kidneys, have

followed my example, and have been well satisfied. I think, therefore,

that lactic bacteria can render a great service in the fight against

intestinal putrefaction.

If it be true that our precocious and unhappy old age is due to

poisoning of the tissues (the greater part of the poison coming from

the large intestine inhabited by numberless microbes), it is clear

that agents which arrest intestinal putrefaction must at the same time

postpone and ameliorate old age. This theoretical view is confirmed by

the collection of facts regarding races which live chiefly on soured

milk, and amongst which great ages are common. However, in a question

so important, the theory must be tested by direct observations. For

this purpose the numerous infirmaries for old people should be taken

advantage of, and systematic investigations should be made on the

relation of intestinal microbes to precocious old age, and on the

influence of diets which prevent intestinal putrefaction in prolonging

life and maintaining the forces of the body. It can only be in the

future, near or remote, that we shall obtain exact information upon

what is one of the chief problems of humanity.

In the meantime, those who wish to preserve their intelligence as

long as possible and to make their cycle of life as complete and as

normal as is possible under present conditions, must depend on general

sobriety and on habits conforming to the rules of rational hygiene.