_facing p. 44._]

Now--and I appeal to the good sense of my readers--would it be better to efface the suffering of those rats, those guinea-pigs, those rabbits, and return to the olden times when the mortality in lying-in hospitals was often 40 per cent. (it is to-day, 0.02 per cent.!)? Must we condemn Lister and Pasteur as great criminals because they dared to inoculate microbes into a few rabbits and bring about in those unfortunate animals--they would have died a long time ago even without that--experimental ailments in order to ward off malignant diseases from thousands and thousands of human beings?

The second discovery which I shall mention is that of the infectiousness of tuberculosis. Thousands and thousands of doctors had had tuberculous patients under their care. Three thousand years ago, Hippocrates described tuberculosis with as much precision as could be done to-day. Ill.u.s.trious physicians in every land had tried to a.n.a.lyse the nature of this terrible disease and to unravel its cause; nevertheless, they were unable, from clinical observation alone, to prove what is to-day quite commonplace knowledge, viz., that tuberculosis is infectious. In 1864, a French doctor, Villemin, conceived the simple and ingenious idea of inoculating rabbits with the tuberculous matter found in the lungs of consumptive patients.

These rabbits became tuberculous; they died in a few weeks with tuberculous granulations in lungs and liver. It was thus demonstrated that tuberculosis was infectious. Later on, in 1878, Koch discovered that the active agent of this infection is a special microbe. But, however important may be the discovery of the microbe of tuberculosis (the tubercle-bacillus of Koch), the essential dominating fact is that tuberculosis is infectious.

As soon as this great fact became known, a profound revolution occurred in social hygiene, in the treatment and in the prevention of this terrible evil. We know now the consumptive man carries in his lungs and sputum the germ capable of developing the same evil in others; consequently we know how to preserve ourselves against tuberculosis. We must purify or destroy the habitations wherein consumptives have lived, burn or carbolise all the sputum, make spitting in public places a punishable offence, take sanitary measures against unhealthy meat, defend our children against contaminated milk--in a word, we are armed against a disease, the sole and unique cause of which, as experimentation alone has taught us, is infection.

Formerly it was believed that diseases were due to a sort of divine anger, or, what amounts pretty much to the same thing, to certain imperceptible epidemic exhalations stretching over whole populations, or attacking isolated individuals, striking like an exterminating angel, as his fancy chose, such or such an unhappy victim. A sort of will or caprice, governed only by chance, was exercised in relation to this disease, and man was powerless, because he was unarmed against chance. He did not even think of it. He resigned himself to being ill, and waited for the disease, without doing anything to fight against it, benumbed under a kind of Oriental fatalism. The doctor shook his head, bore testimony to the evil, and confined himself to prescribing inefficacious treatments which were only, according to a celebrated saying, a long meditation on death.

But the times have changed; there is no longer any fatality in tuberculosis; there is imprudence, there is error, there is vice, and, specially, social vice. We may almost say that, if there are still consumptives in our midst, it is because of our defective social inst.i.tutions. We leave innumerable populations steeped in misery, seven or eight individuals living in the same infected hovel. In the slums of our large cities, swarms of infants are to be found morally and materially perverted by misery. Therefore, if consumption still exists, it is our own fault; it is no longer as it was in olden times, when we knew not, because _now_ we know. The plague can be battled with; and if it still has so much power left, it is because we have not the courage to apply to public and individual hygiene the treatment science has definitely shown us should be applied. To foresee is to know; and now that we know, we must not forget that it is to experimenters, and to experimenters alone, that we are indebted for this great benefit.

Moreover, however imperfect our defence against tuberculosis may still be, it is by no means _nil_; great progress has been made; the mortality has decreased in a considerable proportion. During the last twenty-five years, it has decreased by about 25 per cent., and notably in England, where the laws of public hygiene, energetically upheld by the good sense of the people, are strictly applied, the mortality has diminished by 50 per cent.

This is only a beginning, and the near future will bring about the complete extermination of the disease.

Now, honestly, I ask if the rabbits which Villemin sacrificed weigh more in the scales of universal progress, and even in public morality, than the three millions of individuals who, by progress in hygiene, have been preserved from an early and painful death. I estimate at a high price the life and the sufferings of fifty rabbits, but, at the risk of appearing a barbarian, I prefer, to these fifty rabbits, the three millions of young people who have been saved by Villemin's discovery, and the millions which it will still save.

All the more so, inasmuch as experimental studies on tuberculosis have not only preserved men; they have also preserved animals. Thanks to Koch, there is now a very simple way of recognising if an animal is or is not tuberculous. Koch was able to extract from tubercle bacilli, a substance which he has called _tuberculin_. At first he thought tuberculin cured the disease; but this was an error. Subsequent experiments showed that tuberculin exercised quite a different action to that of healing. It has the property, when injected in small doses into a tuberculous animal, of provoking an intense fever, whilst it produces no reaction whatsoever in a normal animal. If, therefore, tuberculin is injected into every animal in the cattle shed, we can feel sure--and this is impossible otherwise--that such or such animals are tuberculous or healthy. All cows that show a rise in temperature after an injection of tuberculin are tuberculous; the others, on the contrary, are in good health.

Thus the sanitary inspection of stables and cattle-sheds can be carried out thoroughly; and we are now able to protect not only men but also animals from the disease of tuberculosis.

Such results could only have been obtained at the cost of many and methodical experiments. Whatever may be the genius of anti-vivisectionists, they would never have been able to imagine anything similar had they been left to their own intellectual powers. It is not in the study that we are able to discover this long series of unforeseen, extraordinary, almost miraculous facts which laboratory experimentation has been able to find out. Man, said Pascal, tires of conceiving sooner than Nature tires of providing; and experimentation is man's method of interrogating Nature.

The third discovery which I shall take as an example demonstrating the value of experimentation, is the history of _Serotherapy_. And I may be permitted to dwell somewhat on this subject as I had the good fortune, in 1888, of making the decisive experiment which was the beginning of serotherapy.

Whilst inoculating some rabbits and dogs with a microbe taken from pus (_Staphylococcus pyosepticus_), I developed a certain disease both in the rabbits and in the dogs. But the dogs did not die, whilst all the rabbits died from the results of the inoculation. I thought then that, the cause of that resistance being due to the difference of blood, I might be able to make the rabbit refractory to the infection by injecting it with the blood of a dog in normal health. The experiment succeeded. The rabbits which had received the blood of the dog, when they were afterwards infected with the staphylococcus, became very ill but did not die. Later on, I took, not the blood of a dog in normal health, but the blood of a dog that had received the infection of the staphylococcus and had recovered from that infection, and I injected this blood into the rabbits. _Now the rabbits that received the blood of the infected, healed dog had acquired complete immunity to this form of microbe infection_: the principle of serotherapy was discovered (5th Nov. 1888).

[Ill.u.s.tration: "L'ENFANT."

_In Musee du Luxembourg, Paris._

_facing p. 53._]

Since then, serotherapy has been applied, by Behring in Germany and by Roux in France, to diphtheria (1892). These two savants showed that the blood of animals, and especially of horses, that had been infected with diphtheria and cured, could, when injected into patients attacked by diphtheria, diminish, in an extraordinary proportion, the duration and intensity of the disease. There is no other treatment for diphtheria to-day. A doctor is guilty, and even criminal, if he does not use it, for the therapeutic results of this treatment are marvellous.

I do not speak of clinical observation only. All those who have seen the effects of one of these injections of serum on children down with diphtheria are veritably stupefied at the resurrection which they witness only a few minutes after the injection. The unfortunate child with his purple face and convulsed limbs, scarcely breathing, comes back to fresh life as soon as he has received the beneficent injection of serum. The facts are so decisively clear that even if we have only seen them once we can never again forget them. But I shall simply call the attention of my readers to the following statistics, the result of more than 500,000 observations made in England, in the United States, in France, in Russia, in Germany, in Italy, in Austria, in fact everywhere: the death-rate in diphtheria before 1892 (for the serotherapic method took four years to become known and practised) was 45 per cent. After 1892, this death-rate fell to 12 per cent.[8] Consequently, out of every hundred patients suffering from diphtheria, thirty are saved by the serotherapic treatment.

Let us stop for a moment to consider these figures, which seem mere abstractions to those who have not reflected. At the present time, about 300,000 children per annum in France are attacked by diphtheria; that makes 4,500,000 from 1892 to 1907. The proportion of 30 per cent. is therefore 1,350,000. The number of children who have been saved in France alone by serotherapy in fifteen years is therefore 1,350,000. Let us put it in round numbers at one million only; this would be sufficient to justify the death of the twenty-five dogs and the one hundred rabbits which I sacrificed, and of the two hundred horses which Behring and Roux used for the preparation of the anti-diphtheria serum. A million families in mourning, a million hopes mowed down in the bud! Only fanatics would dare to say this weighs for nought in the balance.

Moreover--and why should I not say it aloud?--this so-called humanity of anti-vivisectionists seems to me the ant.i.thesis of humanity. To satisfy a conception which they have forged out of a certain hazy ideal, they make quick shrift of human life and suffering. A hundred weeping mothers, a hundred unfortunate children with gaping throats, suffocating, gasping, the death-rattle at hand--that is what these sensitive souls declare is nothing beside one rabbit which has had to receive a little blood of a dog into its abdomen! These philanthropists are creatures of a fixed idea! Let humanity suffer, weep and die! What does that matter, provided that their fixed idea, driven right up to the hilt of delirium, triumphs! After all, if they persist in believing that the faint and uncertain suffering of a sick rabbit is not worth the certain and excruciating suffering of a thousand human creatures, I can say but one thing: I pity them from the very bottom of my heart.

These examples--antisepsis, tuberculosis, and serotherapy--will suffice perhaps to justify experimental pathology. There is now another experimental science which I am going to try to justify also. This is _Therapeutics_.

We are only able to learn the action of medicaments by studying the action of poisons, for all medicaments in strong doses are poisonous. Now, to understand a poison thoroughly, we must experiment with it on the animal.

Simpson administered chloroform to men only after Flourens had determined its anaesthesic properties on animals. Liebreich, after he discovered chloral, studied its physiological properties on animals, and only after long and learned studies was he able to give it a place in human therapeutics. At the present day, chloral is one of the most extensively used medicines, one which has relieved innumerable patients. When I carried out my research on chloralose, before studying its effects on myself, I began by giving it to cats and fowls. I was ignorant of the degree of toxic power of this new, still unknown substance, and, at the risk of appearing very pusillanimous, I did not wish to begin on myself; I preferred trying it on a fowl. Not that I estimate my life very highly, but after all, however low an estimate I may place on my own life, I think it is worth more than that of a fowl. Many other medicines have been thus experimented with on animals before it was possible to ascertain their effects on man.

Kocher discovered cocaine, Knorr antipyrine; and these two admirable medicines did not find their way into therapeutics until their mode of action and their toxic power had been ascertained on animals.

In a word, the whole of present-day therapeutics has for foundation, not only ancient clinical observation, which it would be supremely foolish to disdain, but also the experiments of modern times, which it would be equally foolish to proscribe.

Perhaps certain people imagine that there are no therapeutics, and that we can replace by auto-suggestion, prayer, or hypnotisation, everything which doctors generally use to cure or allay disease. It is difficult to reply to such objections, because those who make them have never opened a work of science nor seen a patient. They see things as they wish to see them. They imagine that the exterior world is constructed according to their interior vision, and they do not deign to come into contact with reality. They believe that enthusiasm can supply the place of instruction, and that a certain doubtful generosity can replace profound and patient study. They maintain perhaps that chloral does not make one sleep, that salicylate of soda does not alleviate rheumatic pains, that bromide of pota.s.sium does not check attacks of epilepsy. Perhaps they will even continue to say so for a long time to come. Let them talk; progress will be made without them.

_Les chiens aboient et la caravane pa.s.se._

FOOTNOTES:

[7] See footnote, p. 17.

[8] These statistics can be found in all technical works; and I refer those who may be curious to study them in detail to the special memoirs and excellent treatises on pathology which have been published in England, France, and Germany.

See also appendix.

CHAPTER V

SERVICES RENDERED TO SCIENCE AND HUMANITY BY EXPERIMENTAL PHYSIOLOGY

I now come to a favourite theme of anti-vivisectionists, viz., that experimental physiology has produced nothing, and that the differences of opinion among _savants_ are so considerable that this alone proves the impossibility of vivisection ever establishing anything permanent.

Here again it is difficult to reply because of the very ignorance of the honourable gentlemen who criticise us. Most certainly there still remain many disputed and disputable points in physiology, and nothing is easier than to find therein striking and abundant contradictions. If we wished to amuse ourselves, we might write five or six big volumes on the subject; but let us leave this tedious and useless labour to the anti-vivisectionists to accomplish to their hearts' content. I prefer to tell them, what they do not wish to know perhaps, that contradiction is the very essence of science. As our demonstrations appeal not to faith but to reason; as we admit free discussion, free investigation from every side; any proposition must have mult.i.tudinous and positive proofs in its favour before it can be adopted without hesitation. Even our opinions were never prescribed by faith or violence; we take pleasure in provoking discussion and contradiction. With our adversaries' leave be it said that a dogmatic, irreproachable book, where there was no place for hesitation or doubt, would be the very negation of science. Even the treatises of geometry and mechanics, although non-experimental, rational sciences, sometimes contradict themselves. It has been rightly said that the history of science is the history of human errors--errors which, little by little, draw nearer and nearer to supreme truth without ever attaining it. We must understand this, or we shall be rebelling against the conception of scientific truth.

Now, in treatises on physiology, we find a number of well-demonstrated truths, and a still larger number of truths only half demonstrated, and, consequently, contested. Our successors will also certainly find in our books of to-day an enormous number of errors.

What conclusion is to be drawn from this fact? Have those who reproach the science of physiology with being only a tissue of contradictions and errors ever opened a book on physiology (for example, the text-book of Schaefer, in two large, compact, closely written volumes of 1000 pages each)? They would there find thousands of positive, incontestable facts on all the questions which concern physiology.

Let us take, each in its turn, the great functions of life, and we shall see that they have become known only by experimentation.

1. _The Circulation of the Blood_, suspected by Michel Servet, Realdo Colombo, and Andreas Cesalpin, was really established by Harvey in 1628.

Yet Harvey was only able to demonstrate it by experiments performed on the living bodies of frogs and deer. Since Harvey's time, the laws of the circulation have been established with admirable precision. Hales demonstrated the pressure of blood in the vessels. Chauveau and Marey introduced into the heart of a horse an apparatus which enabled the pressure of the blood in the heart, in the arteries, and in the veins, to be measured. Weber found that the pneumogastric nerve stopped the heart's action. Ludwig applied the graphic method to the circulation. Delicate instruments have been constructed which give diagrams of the pulsations and measure the pressure of the blood in the arteries and in the heart of man.

Claude Bernard discovered the nerves which regulate the movements of the vessel walls. In short, the whole history of the circulation is due solely to vivisections, and it would be ridiculous to speak of our uncertainties in this respect; for the essential mechanical or nervous laws of the circulation are as well known now as those of the combinations of nitrogen with oxygen.

2. _The Respiration_ remained profoundly unknown, as to its inmost nature, right up to Lavoisier's time. Lavoisier placed some guinea-pigs in a box filled with ice, measured the quant.i.ty of heat thrown off, the quant.i.ty of oxygen consumed, the quant.i.ty of carbonic acid produced; and he was thus able to deduce a fundamental law of life, viz., that life is essentially combustion. He made experiments on himself also; but however great one's respect for the life of a guinea-pig may be, must it be considered wrong that Lavoisier should have experimented on the guinea-pig before experimenting on himself?

As for the laws which regulate this consumption of oxygen and this production of carbonic acid, to discover these it was necessary to put into cages animals of every species and of every size. And there is, perhaps, not a single physiologist who has not made this experiment, at the risk of annoying the cats and dogs thus exposed--without, as far as that goes, doing them any harm--to varied temperatures or to different diets.

Moreover, in order to study the respiratory exchanges, physiologists experiment on man as well; is, therefore, the extraordinary scruple against experimenting on animals to be imposed upon them also?

To take an excellent example of the services which experimental physiology can render not to science only--which would, indeed, be quite sufficient to justify them--but to humanity, I will cite the experiments of Paul Bert with relation to elevated atmospheric pressures. There are certain workmen who are obliged to work under water, at a depth of 20 to 30 yards, for the construction of piers and bridges, or the exploration of sunken vessels.

Now, it had long been observed that some of these men died suddenly on returning to the surface. Experimental physiology was able to discover the cause of that sudden death. When a man (or an animal), after having been subjected to several times the normal atmospheric pressure, is suddenly released from this pressure, the nitrogen dissolved in the blood is disengaged suddenly: this produces gaseous embolism, that is to say, bubbles of gas are formed, which block the blood-vessels and prevent the blood circulating in the capillaries. Knowing this, the death of men working at a pressure of four atmospheres could then be avoided by releasing them slowly, that is by bringing them slowly back to the normal atmospheric pressure. Is it barbarous to attach more importance to the death of these men than to the death of the few dogs and mice that served to establish this law?