Chapter II (2)

After all, there is nothing surprising in the fact that the vital resistance of a newly-born guinea-pig should differ from that of an adult one. But what is very remarkable is, that if an older guinea-pig be inoculated with the blood of one a day old; if a third, still older, be inoculated with the blood of the second; and so on; the virulence of the microbe will be gradually reinforced--that is to say, the usual habit of this parasite to develop itself in the body of the animal will be restored. The process may be likened to that of an animal or vegetable species, passing by successive stages and long sojourns, from one region to another very distant one, subjected to quite new conditions of climate, and gradually becoming acclimatised to the last one. How great, then, must be the importance of the medium of cultivation, with regard to the virulence of the microbes of communicable diseases! Cultivating the microbe by passing it from one guinea-pig to another, we soon arrive at a strength capable of killing guinea-pigs of a week, a month, or several years old, until at last the smallest drop of the blood of these guinea-pigs suffices to kill a sheep; and from the sheep we may pass on to the ox.

The same is the case with the microbe of fowl cholera. When it has ceased to have any effect upon fowls, its virulence can be restored by inoculating small birds. Blackbirds, canaries, sparrows, all die, if the virus has not been too much attenuated; and the effect is similar on young chicks. Thus by several successive transitions from bird to bird a virulence may be fostered capable of destroying full-grown fowls.

These facts suggested to Pasteur certain inductions which may be well founded. Is not the attenuation of the virus by the influence of the air one of the factors in the extinction of great epidemics? And may not the reappearance of these scourges be accounted for by the reinforcement of the virulence?

'The accounts which I have read,' Pasteur remarked some months ago, 'of the spontaneous appearance of the plague in Benghazi in 1856 and in 1858 tend to prove that this outbreak could not be traced to any original contagion. Let us suppose, guided by the facts now known to us, that the plague, a malignant disease belonging to certain countries, has germs of long duration. In all these countries its attenuated virus must exist, ready to resume its active form whenever the conditions of climate, of famine, of misery present themselves afresh. The condition of long duration in the vitality of the germs of evil is not even indispensable; for, if I may believe the doctors who have visited these countries, in all places subject to the plague, and in the intervals of the great outbreaks of the epidemic, cases may be met with of people attacked with boils, not fatal, but resembling those of the deadly plague. Is it not probable that these boils contain an attenuated virus of the plague, and that the passage of this virus into exhausted bodies, which abound only too freely in periods of famine, may restore to it a greater virulence?

'The same may be the case with other maladies which appear suddenly, like typhus in armies and in camps. Without doubt, the germs which are the authors of these diseases are everywhere scattered around, but attenuated; and in this state a man may carry them about him or in his intestinal canal without great damage. They only become dangerous when, by conditions of overcrowding, and perhaps of successive developments on the surfaces of wounds, in bodies enfeebled by disease, their virulence is reinforced.'

_ETIOLOGY OF SPLENIC FEVER._

M. Pasteur had triumphed over splenic fever with as much rigour as precision. But he considered that he had still to make one further investigation. He had established the effects of the pest; he had discovered a preventive method with which to combat it: he now wished to know the origin of the evil. Whence comes splenic fever? Why is it endemic in certain departments of France, in certain parts of Russia, Germany, Austria, Italy, Spain, and America? How is it sustained? It was for a long time believed that splenic fever was born spontaneously under the influence of various accidental causes. M. Bouley has related, in his learned work on the 'Progress of Medicine by Experimentation,' that in 1842 the Minister of Agriculture, M. Cunin-Gridaine, at the request of the deputies of the departments that were ravaged by the epidemic, entrusted to M. Delafond, a professor of the school at Alfort, the task of investigating this malady, commonly called the 'blood disease,' in the districts in which it was raging. He was to search out its causes, and ascertain whether they did not result from the system of cultivation prevalent in the country.

M. Delafond arrived in Beauce. One fact struck him--namely, that almost all the animals attacked by the disease were young, fine, and vigorous: those, in short, that gave the best promise. Viewing the richness of the soil and the abundance and quality of the crops in conjunction with this observation, Delafond at once elaborated a speculative theory. 'The blood disease,' said he, 'is nothing but an overfulness--an excess of blood circulating in the vessels, and especially the predominance in that liquid of red globules.'

Starting from this idea, his one object was, by means of logical deduction, to trace everything to this fundamental error. He analysed the soil, and demonstrated to what extent it was fitted to furnish crops that were rich and abounding in nutritive properties. He analysed the plants. He then complacently referred the richness of blood of the Beauce sheep to the richness in nitrogenous principles of the substances on which they were fed. He examined the lesions of the diseased animals, and concluded that they were the consequence of the blood containing too large a proportion of the organic elements, called globules, fibrine, albumen, and too small a proportion of water.

'Reduce the proportion of nutritious elements,' he wrote as his advice to the agriculturists, 'mix roots with all that is too rich in nitrogenous principles, and you will reduce in proportion the losses caused by the excess of the ultra-nutritious substances with which you supersaturate your cattle.'

'Such is the very logical conclusion to which Delafond was led,' adds M. Bouley, ridiculing these observations, based on a method of reasoning, instead of on the experimental method. 'And as a fresh proof of his theory he mentions the fact that the disease decreases as you descend the country towards the Loire. On the right bank of that river--in Sologne, for instance, which is a low, sandy, damp district--blood disease is unknown. In the arrondissements of Gien and Montargis and in parts of those of Orleans and Pithiviers it prevails but little. There, Delafond imperturbably remarks, the soil is sandy and the herbage not nearly so rich as in the Beauce plateau; and there the blood disease is consequently less common.'

When we consider that such opinions could be written unchallenged only forty years ago, that they could even borrow a scientific character from the inspiration that gave them birth, we can see the progress that has since been made, and can realise how great were the obscurity and uncertainty which have been dispelled by the experimental method.

The presence of a parasite having been brought to public notice in the blood of animals suffering from splenic fever, at the very time when Pasteur had shaken the belief in spontaneous generation, people grew accustomed to the idea that the stricken animals might have contracted the germs of the malady from the outer world, without any spontaneous birth, strictly so called, of the disease. This opinion was strengthened by a knowledge of the spores of the splenic bacillus. Pasteur, aided by Messieurs Chamberland and Roux, commenced experiments with a view to solving this difficult etiological question. The first experiments took place in the fields of a farm at the village of St. Germain, near Chartres. Several groups of sheep were fed on lucern grass which had been sprinkled with artificially-reared splenic fever bacteria, or with their germs or spores. Although all the sheep of the same group absorbed an immense number of the spores of the parasite, many survived, even after being visibly affected. Those that died showed all the symptoms of what is called spontaneous splenic fever. The period of incubation lasted as long as eight or ten days, although, in its latter stages, the disease exhibited those startling features which have caused a belief that the incubating period is a very short one--short, that is to say, for those conditions of contagion where the parasite is not deposited in its pure state under the animal's skin.

But if prickly plants (notably the pointed ends of dried thistle leaves, or beards of barley blades cut into little bits about a centimeter in length) were added to this infected food, the mortality increased to a striking extent. On examination after death, the lesions of these animals were found to be similar to those observed in sheep which were attacked by splenic fever in sheds, or which died of the disease in the open fields.

From that time forward, the idea which had been predominant in the minds of Pasteur and his fellow-workers during all their inquiries, was materially strengthened. They were convinced that the animals which died of blood disease in the department of Eure et Loire had been infected by germs or spores of the splenic microbe contained in their food; but the question remained, Whence came these germs?

From the moment when all belief in the spontaneous generation of the parasite is rejected, attention is naturally drawn to the possible consequences which may arise from burying in the earth animals which have died of splenic fever. In the greater number of cases, when the knacker's establishment is too far off and the dead animal is of little value, a trench is dug on the spot, at a depth varying from half a meter to a meter. If the animal dies in a field, it is buried where it falls; if it dies in a shed the body is carried into a neighbouring field. There it is buried, and putrefaction sets in; and since all the splenic fever filaments of the blood are destroyed by putrefaction, it was thought that no dissemination of the germs of splenic fever, after the animal had been buried, could occur. Pasteur showed that this opinion rested on a superficial observation. Even when the animal is not cut up, blood spreads itself outside of the body in more or less abundance. Is it not an habitual characteristic of the disease, that at the time of death blood issues from the nostrils and the mouth, and that the urine is often bloody? All around the corpse, therefore, the earth is polluted with blood. Moreover it takes several days for the splenic fever microbe to resolve itself into harmless granulations by the action of gases, other than oxygen, which putrefaction generates. During this time, the excessive inflation of the dead body causes the liquids of the interior to issue from all the natural apertures. How often also, a rent in the skin or the tissues increases this flow. The blood and other matters, mixed with the surrounding aerated soil, are no longer in the conditions of putrefaction, but rather in those which form a suitable medium of cultivation for the microbe. Experiments confirmed these views. Adding some splenic fever blood to earth sprinkled with the water of yeast, or with urine, at summer temperature, or at the temperature which the fermentation of a dead body keeps up around it, as in a dung heap, in less than twenty-four hours the splenic fever filaments deposited with the blood had multiplied and resolved themselves into spores. These spores were afterwards found in their state of latent life, ready to germinate and to communicate splenic fever, after remaining in the earth for months, and even years.

These experiments, curious as they were, were only, so to speak, laboratory experiments. It was necessary to investigate what happened in the open country with all the variations of dryness, of damp, and of cultivation. A happy inspiration came to Pasteur and his assistants. They had buried in the midst of summer, in an isolated corner of the farm of St. Germain, near Chartres, a sheep which had died of natural splenic fever, and of which they had made the autopsy. Ten months afterwards, and again fourteen months afterwards, the idea occurred to them of collecting some of the earth from this grave. After having examined it, and established the presence of the spores of the microbe, they produced, by the inoculation of guinea-pigs, the splenic disease and death. But the circumstance which deserves the greatest attention, is that the same experiment was successfully made with the earth on the _surface_ of the grave, though this earth had not been disturbed during the interval. Some experiments were afterwards made on the earth of some trenches dug in a meadow of the Jura, where some cows which had died of splenic fever had been buried at a depth of two meters. Two years afterwards, by successive washings of the earth on the surface of the graves, deposits were extracted which at once produced splenic disease. At three trials within these two years the same surface earths produced splenic fever, while, away from the graves, the earth exhibited nothing of the kind. Finally, Pasteur and his assistants proved that on the surface of the earth which covered the buried animals, the germs were again found, after all the operations of ploughing, sowing, and reaping.

But how, it will be asked, can the earth, which is so powerful a filter, allow the germs of microscopic organisms to rise again to its surface? Is one not tempted here to quote Pasteur against himself, since, in his joint researches with M. Joubert, Pasteur had proved that the waters of springs issuing from the earth, even at a shallow depth, are entirely free from germs? Such waters, nevertheless, being supplied from the earth's surface, which is constantly washed by rain, the effect must be to carry down the finest particles to the springs. But these latter, notwithstanding conditions so conducive to their pollution, remain perfectly pure. Can there be a better proof that earth of a certain thickness will arrest all solid particles, even the most minute? Nevertheless, in these experiments on splenic fever, we hear of microscopic germs, starting from the depths and coming up to the surface--that is to say, in a direction contrary to the flow of the rain. This is an enigma.

The explanation will cause surprise. The earth-worms transport the germs, and bring up, from the depths where they lie buried, the terrible microbes. In the tiny cylinders of earth which the worms deposit on the surface of the soil, after the dews of the morning or after rain, the splenic germs are to be found. It is easy to prove this directly. If in earth, with which spores of the microbe have been previously mingled, we place some worms, and at the end of several days open the bodies of these worms, with all necessary precautions, so as to extract from them the earthy matter which fills their intestinal canals, we find in them large numbers of splenic fever spores. It is, then, absolutely proved, that if splenic fever germs exist, as they often do, in the light earth which covers the pits in which animals dead of that disease lie buried, these germs result from the disintegration by rain of the little excremental cylinders deposited by the earth-worms. The dust of this disintegrated earth spreads itself over the grasses on a level with the soil, and thus it is that animals come to find on the pasture-field, and in particular kinds of forage, the germs of splenic fever by which they are infected.

'In these results,' said Pasteur a short time ago at the Academy of Medicine, 'what outlooks are opened to the mind in regard to the possible influence of earths in the etiology of diseases, and the possible danger of the earth of cemeteries!'

The earth-worms also bring to the surface other germs, which, while they are as harmless to the worms as the splenic germs, are nevertheless bearers of diseases to which animals are liable. All sorts of germs are found in them, and the germs of splenic fever are in fact always associated with those of putrefaction and septicæmia.

* * * * *

'And now,' concluded Pasteur, when laying before the Academy a rapid survey of the etiology of splenic fever, 'is not the remedy naturally indicated? We should never bury animals in fields destined either for cultivation, for forage, or for sheep pasture. When it is possible a sandy soil should be chosen for the purpose, or any poor calcareous soil, dry, and easily desiccated--in a word, soil not suited to the existence of earth-worms.' M. Tisserand, Director of Agriculture, has remarked that splenic fever is unknown in the region of the Savarts of Champagne, although it is surrounded by countries invaded by the disease. If the conditions of commerce introduce splenic fever, it is but a passing accident. Must not this be attributed to the fact that in these poor soils, such as that of the camp at Châlons, where the thickness of arable soil is only from 4 to 5 inches, superposed upon chalk, the worms cannot live? In such a soil the burial of a splenic fever animal will give rise to great quantities of germs, which, owing to the absence of earth-worms, will abide in the depths of the soil and remain harmless. Finally, it has been proved that the countries subject to splenic fever have an argillaceous-calcareous soil, and that the disease is unknown in schistose and granitic soils. The contrast of the results, in relation to such differences of soil, is seen sometimes in the Department of the Aveyron, between the right and left side of one and the same road or watercourse.

May we not now in all confidence assert that, if the cultivators choose, splenic fever may soon be a thing of the past among their animals, their shepherds, and among the butchers and the tanners of the towns, because splenic fever and malignant pustule are never spontaneous? The disease exists only where it has been sown, or where it has been diffused by the unconscious instrumentality of the earth-worm.

The progress of vaccination will also contribute to the disappearance of splenic fever; for this preventive, if extensively used, as there is no doubt it will be, must end by establishing a race of domestic animals which, having all sprung from vaccinated parents, will in consequence be more resistant to the disease in its worst form. It will be with them in relation to splenic fever as it is with ourselves in relation to small-pox. It is a well-known fact that the ravages of small-pox are much less considerable in our days than when it first appeared in Europe. It is difficult not to attribute this, at least in part, to the prevalence of vaccination.

In the populations where small-pox is introduced for the first time it has an exceptional intensity. Some months ago a significant fact of this nature occurred in Paris. A whole family of Esquimaux perished from small-pox in the 'Jardin d'Acclimatation.' They had never been vaccinated, nor had their ancestors. They were new to the attacks of small-pox, which did not spread beyond them.

_METHOD OF DISCUSSION AND CONTRADICTIONS._

Every new discovery produces a revolution in general ideas; a revolution gladly hailed by some, but opposed by others as disturbing their habits of thought and reasoning. Those also who are thrown out in their calculations, while engaged in working out a problem in any way similar to the one that has been solved, too often atone for their dilatoriness by furious denial of the newly asserted truth. The great fact of the attenuation of virus, the artificial production of the vaccines of chicken cholera and of splenic fever, the importance of their employment for the preservation of animals from these diseases, excited throughout the world a surprise and enthusiasm which passionate critics soon sought to disparage. The fiercest attack was from Germany. It commenced immediately after Pasteur's triumph at the International Congress of Medicine held in London in 1881. The German doctor Koch and his colleagues, MM. Gaffki and Lœffler, published in Berlin, in the report of the German Sanitary Office, a kind of scientific tirade against the discovery of virus vaccine, and the possibility of utilising it in the large operations of cattle-breeding.

At the London Congress Dr. Koch had said to a French physician that the possibility of attenuating virus was a thing too good to be true. The whole question was therefore reopened by Dr. Koch and his disciples. At first Pasteur let the torrent flow; but, not being the man to give way before an adversary, he at last declared that the attacks of the German savants must be repelled at Berlin itself. Continual applications for splenic vaccine were made to him from different parts of Germany. M. Pasteur replied that, seeing that the discovery was so formally contested in Prussia, it would be well, before sending any vaccine abroad, to institute a great demonstrative experiment, as had been done at Pouilly-le-Fort.

Dr. Roloff, head of the Veterinary School of Berlin, hastened to take the initiative, by an application to the German Minister of Agriculture. The minister at once nominated a Commission to follow the experiments in vaccination and to draw up a report for the German Government. M. Pasteur entrusted the conduct of the vaccinations to his new colleague, Louis Thuillier, who accepted with deep and silent joy the management of an experiment that was to test a French discovery. He was always ready for anything, this brave Thuillier, who was destined to die, a martyr to the cause of science, in the full promise of his youth, and in the full hope of glory. His courage and his work were alike great and silent. In the laboratory he would spend days, even weeks, without speaking, bent over his microscope with tenacious resolution, endeavouring to follow Pasteur in all his investigations: proud to live near his illustrious master, happy to be his disciple and to be loved by him almost as a son. What a vacancy he has left in the laboratory! What a place he might have held in science!

The composition of the German Commission, over which M. Beyer, member of the Superior Council of Government, presided, showed clearly the importance attached by Germany to the investigation of this French discovery. Among its members was the famous Professor Virchow.

The experiments were carried out on the estate of Pakisch. The minutes and reports of the Commission left no doubt as to the correctness of the facts announced by Pasteur. But, as the negations of Dr. Koch and his colleagues embraced questions beyond that of the prophylaxy of splenic fever, Pasteur did not rest content with this initial success; he sought for a fresh opportunity of convincing his opponents. This opportunity occurred in September 1882, when an International Hygienic Congress was held at Geneva. Thither went Pasteur, hoping to meet Dr. Koch at the sittings; and he was not disappointed. Dr. Koch was there, surrounded by his disciples. From the tribune of the Congress, Pasteur refuted his criticism, exposed his errors, and challenged him to a discussion in the presence of competent judges. There was an instantaneous salvo of applause, and everyone awaited Dr. Koch's reply. But he declined all debate, reserving his case for careful and deliberate statement in the press.

It took three months for Dr. Koch to bring out a small pamphlet, and these three months had borne their fruit. The discovery of the attenuation of virus, which had been so vehemently attacked only a year before in the report of the Sanitary Office, was now extolled by Dr. Koch as a discovery of the first importance. Being, however, unwilling absolutely to stultify himself, he continued the attack by denying its efficacy in practical agriculture.

* * * * *

The clear, direct style of argument, which goes straight to its point, was invariably adopted by Pasteur.

'Contradictions may retard, although they cannot ultimately prevent, the recognition of truth,' he once remarked to me when walking in the gardens of the École Normale; 'that is why it is so important to remove the obstacles which temporarily clog and hamper it. In scientific discussions, it is not as in politics,' he added with a smile, 'where demonstration is often difficult. In the natural sciences, doctrines must be based on an assemblage of results, of observations, and of experiments. If a doctrine is challenged, it seldom happens that its truth or falsehood cannot be established by the application of some crucial test. Even a single experiment will often suffice either to refute or consolidate the doctrine.'

Reviewing the labours of the past forty years, Pasteur then called to mind the numerous controversies in which he had been engaged. Not only had he been attacked by Pouchet and Joly on the question of spontaneous generation, by Liebig on the subject of fermentation, by Germans and Italians regarding the attenuation of virus, but every one of his assertions had been met with such passionate opposition that, from sheer weariness, he had invariably ended by referring the matter to some authorised commission, only asking it to put an end to all strife by coming to some definite decision.

The upshot was at times somewhat amusing. For instance, when Pasteur described to the Academy of Medicine how, simply by lowering the temperature of a hen, he had made her susceptible to inoculation with splenic fever, the facts were at once denied by M. Colin, a professor of the school of Alfort. Pasteur immediately requested that a commission might be named, which should include both himself and his opponent among its members. This was on a Tuesday, one of the Academy days of sitting. The following Saturday, in presence of the whole commission, Pasteur produced four hens that had died of splenic fever. M. Colin himself conducted the autopsy. It was clear to everyone that their blood was full of the filaments of the splenic fever parasite. The _procès-verbal_ was drawn up and signed by all the members of the commission, necessarily including M. Colin. The following Tuesday it was read at the sitting of the Academy. To cover his retreat M. Colin now contended that the hens had taken splenic fever not because they had been subjected to a chilling process, but because, so as to keep them in the water, the poor creatures had had their wings and feet tied to planks. This sentimental objection was disposed of by comparative experiments that had been made on hens similarly tied and inoculated, but not chilled. The latter had in no case taken the disease.

At the Academy of Sciences, some days later, a mine was sprung upon Pasteur by a posthumous publication of Claude Bernard's. He again submitted this abruptly raised question to the decision of the Academy. A series of experiments had been found among Bernard's papers, having as their object the inauguration of a new method of spontaneously generating the substance which causes the fermentation of the must of the grape.

'I will start for the Jura,' said Pasteur. 'In the midst of my vineyard, which,' he proudly added, 'is ten meters square, I will cover over some stocks with an improvised frame. These stocks will go on living and bearing grapes, which will ripen. It is now July. At this time of year, as I have already declared, the germs of the cellules which form the ferment of the grape in the vats do not yet exist, either on the green grapes, on the bunches, or on the vine leaves. I will envelop the bunches of the stocks that are underneath the frame with a layer of cotton wool that has been raised to a temperature of 150 degrees Centigrade. This done, I will come back to Paris with the keys of the frame in my pocket, not returning to the Jura until the vintage season, at the beginning of October. I predict to the Academy, that the grapes wrapped in cotton wool under the frame, and which will have grown ripe, may be crushed in the open air, and that the juice coming from them will not be capable of fermentation.'

This prediction was fulfilled. In October, Pasteur returned to the Jura, plucked off several of these stocks, laden with ripe bunches, and brought them with the utmost care to Paris. He had at last the satisfaction of depositing them intact on the table of the Academy of Sciences. He then invited M. Berthelot (editor of Bernard's pamphlet), and all his colleagues, to cut off as many bunches as they pleased. 'Only crush them in contact with pure air,' said he, 'and I defy you to produce fermentation.'

How often was Pasteur obliged to return to facts already proved, not only at the Academy of Sciences, but at the Academy of Medicine, where M. Jules Guérin, at the age of eighty, challenged him to a duel as his scientific ultimatum! If M. Pasteur at times pleaded his cause with too much passion, it was the passion of truth, the burning desire to convince, which lent such power and defiance to his vibrating voice. He could not endure his work to be attacked--not from pride, none was more modest than he--but from irritation at the denial of positive facts; facts of which he was a thousand times assured, and which all the world might verify. No one now remembers these discussions. Time has passed, and opposition has been overthrown. It has been granted to Pasteur to see, everywhere around him, the beneficent results of his discoveries. From all parts, from his own as well as from foreign countries, such proofs of admiration and gratitude have been showered upon him as are usually granted only to those whose death has atoned for their genius. He has opened up such sources of wealth to industry and agriculture that, as the learned English professor Huxley has truly said, 'Pasteur's discoveries suffice, of themselves, to cover the war indemnity of five milliards of francs paid by France to Germany.' His investigations of contagious diseases have revealed immense possibilities in prophylaxy. But Pasteur considered these marvellous discoveries as a mere beginning. 'You will see,' he often said, 'how it will all grow by-and-by. Would that my time were longer!'

_THE LABORATORY OF THE ÉCOLE NORMALE._

VARIOUS STUDIES. HYDROPHOBIA.

Since the day when a minister told Pasteur, that there were not 1,500 francs in the budget to allow for the expenses of his laboratory, science has obtained a little more consideration. At the present time she has nothing to complain of: her sovereignty is recognised; her schools are becoming palaces; she has an amply sufficient civil list: she is rich enough, in short, to pay for her researches. M. Pasteur's laboratory has had its full share of the well-bestowed generosity of the State. The municipal council of Paris even wished to attach vast dependencies to this laboratory. The old garden of the ancient Collège Rollin was placed at the disposal of Pasteur; who at once hastened to build stables for lodging horses attacked by glanders, stalls for sheltering splenic fever sheep, and kennels for the reception of mad dogs. But, while taking advantage of these hospitable premises, Pasteur still retained, in the basement of his laboratory in the Rue d'Ulm, a whole population of animals under experiment. Isolated in round cages which impart some sense of security, are the rabid dogs; some attacked with furious madness, biting their bars, devouring hay, uttering doleful howls which those who have once heard can never forget; others carrying the germ of this terrible disease, still fawning with a humble look of tenderness, as if imploring attention. Hens and chickens pass their heads through the wooden bars of their coops. From time to time a cock from the bottom of his den crows 'a gloomy dawn.' Rabbits eat peaceably, while little families of guinea-pigs cluster together, and at the least alarm utter a frightened cry. All these animals are destined to be shortly inoculated. Each morning a round of inspection is made in this little hospital of condemned animals. The dead are taken out, carried to one of the upper rooms, and placed on the dissecting-boards.

* * * * *

It is also to such boards that living animals are fastened when it is necessary to experiment upon them. Certainly when one sees a dog lying with a forlorn look, its feet tied, its body trembling from fright, on the point of undergoing, though in full health, a bloody operation, one cannot suppress the feelings of pity. But a single visit to a physiological laboratory suffices to reveal vivisection in its only and true light; that of the interest it offers to science, and the results it may have in store for the benefit of humanity. Moreover, in Pasteur's laboratory, every dog subjected to vivisection is chloroformed. The persons who take up the controversy about vivisection are careful that the outside world shall see only the suffering and anguish of the animal, where the solution of a problem should be the object kept in view. Would the English physiologist Harvey have discovered the circulation of the blood, if he had not practised vivisection on deer in the park of Charles I.? Would Claude Bernard have been able, without vivisection, to demonstrate the glycogenic function of the liver? If Pasteur had not sacrificed some fowls and sheep, would the great scientific fact of the attenuation of virus have been discovered? If 500 dogs had to perish, what would that be, compared with the discovery tomorrow of the cause of hydrophobia, and of the means of protecting humanity against this frightful scourge?

On one occasion, in presence of a large assembly, Pasteur made an experiment on atmospheric oxygen. He placed under a glass bell a bird, which in a short time, after having consumed the oxygen contained in the bell, gathered itself up into a ball, opened its beak, and shut its eyes, as if it were going to die. At this moment Pasteur introduced a second sparrow, which, passing directly from the ordinary air into the bell, without any gradual preparation, immediately fell, asphyxiated. There was a little exclamation of horror and a movement of pity in the audience. While the first sparrow, which had gone through the ordeal unharmed, was set free, and gradually revived, Pasteur turned towards the assembly and said--

'I never had the courage to kill a bird in sport, but when it is a question of experiment I am deterred by no scruple. Science has the right to assert the sovereignty of its aims.'

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But to return to the animals of the laboratory: From the little white mice, which hide themselves in a packet of wadding, to the dogs which bark furiously in their iron cages, all are devoted to death. But it is not only the inmates of the laboratory which daily succeed each other upon the operating and dissecting tables. From divers parts of France, hampers full of fowls which have died of cholera, or of some other disease, are sent to Pasteur. Here is an enormous basket packed with straw containing the dead body of a pig which had died of measles. This fragment of lung, packed in a tin box, belonged to a cow which died of peripneumonia. Other packets are still more precious. Since Pasteur went to Pauillac two years ago, to watch for the return of a ship which was to bring back some passengers attacked with yellow fever, he sometimes receives from a distant country a bottled dose of _vomito negro_.

Everywhere, on the work tables, are to be seen tubes filled with blood, microscope slides carrying little drops. In the stoves are ranged the cultivating flasks, which resemble little flasks of liqueur. The point of a needle dipped into one of these flasks is sufficient to cause death. Enclosed in their glass prison, millions upon millions of microbes live and multiply.

It is really a curious spectacle this workshop of research and discovery. How numerous and varied are the subjects which are being studied, and with what energy and patience does Pasteur attack them! It is not only to the most dreaded diseases that he has applied the germ theory. He has extended it to certain common disorders. Everything to him is a subject for experiment. In May 1879, a person who was working in the laboratory was troubled with boils, which reappeared, as usually happens, at short intervals, sometimes on one part of the body, sometimes on another. Pasteur, whose mind was constantly dwelling on the part played by microscopic organisms, asked himself if the pus of the boils did not contain a parasite, the presence and development of which, and its accidental transport here and there in the body, might be the cause of the local inflammation and of the formation of the pus. The constant reappearance of the evil would be thus accounted for.

The pus of the first boil, which was situated on the nape of the neck, was collected in great purity; some days afterwards, the pus of a second boil, then of a third boil, was collected. The pus, or the blood-stained lymph of the red swelling which preceded the formation of the pus, were sown in a sterilised infusion, and each time a microbe, formed of little spherical points connected in pairs, frequently united in small clusters, was seen to develop itself. The cultivating liquid was sometimes infusion of fowl, sometimes of yeast. In the infusion of yeast the little grains are suspended in pairs throughout the liquid, which is uniformly thickened with them. In the fowl infusion, the grains are united into little clusters, which cover the sides of the vessels, the liquid remaining clear as long as it is not shaken.

New observations were made upon a series of boils, in the case of a man sent to Pasteur by Dr. Maurice Raynaud. The same parasite was again found--a unique parasite, distinct from all others. At the Hospital Lariboisière, a woman whose back was covered with boils, offered another opportunity for experiment, and with the same result. It appears certain, then, that every boil contains a microscopic aerobic microbe, and that to it are due the local inflammation and the consequent formation of pus.

When guinea-pigs or rabbits are inoculated with the cultivating liquids, little abscesses are formed, which, however, quickly disappear. As long as the cure of these little abscesses is not quite completed, one can extract from them the microscopic organism which has formed them. When the little parasite is sought for in the general blood of those attacked with boils it is not found. The cause of this, no doubt, is that an aerobic parasite has always some difficulty in developing itself in the blood. The blood corpuscles appropriate, and do not willingly give up to a foreign organism, the oxygen which they require. There is a struggle for life, and in the struggle against the boils the victory is not doubtful. It might be thought, then, that the little organism of boils does not exist in the blood, but there is no doubt that if, instead of a small drop of blood, one could put several grammes or more into cultivation fruitful results would follow. The little parasite is no doubt conveyed by the blood at one time or other. It is transported from a boil, in the process of development, to another point of the body, where it may be fortuitously arrested, there to cultivate itself and form a new boil.

'It is to be wished,' said Pasteur, 'that a patient would submit to a number of punctures on different parts of the body, distant from boils already formed or in process of formation, and that with the blood thus taken from the general circulation a multitude of cultivations might be carried on. I am persuaded,' he added, 'that, among these cultivations, we should find some fruitful in the little organism of the boils.'

But whilst Dr. Maurice Raynaud gave Pasteur the means of studying boils, Dr. Lannelongue enabled him to investigate that serious disease of the bones and marrow called 'osteomyelitis.' In February 1880 that skilful surgeon, who has published a highly esteemed work on osteomyelitis, and on the possibility of its cure by trepanning the bone, followed by washings and antiseptic dressings, conducted Pasteur to the Hospice Trousseau. A little girl twelve years of age, attacked with this cruel malady, was about to be operated upon. The right knee was much swollen, as was also all the leg to below the calf, and a part of the thigh above the knee. After having chloroformed the child, Dr. Lannelongue made a long incision below the knee, from which pus flowed abundantly. The bone of the tibia was laid bare for a considerable length. Three trepanning perforations were then made in the bone, from each of which the pus issued in great quantities. Pasteur carefully collected, with all the conditions necessary to the preservation of their purity, the pus of the exterior and the pus of the interior of the bone, and, returning to his laboratory, he examined them attentively. The direct observation, by a microscope, of the two specimens of pus was extremely interesting. It was obvious that they contained, in large quantities, an organism like that of boils, in pairs of two or four, and also in parcels, some with a clearly defined outline, others scarcely visible, and with very faint outlines. The external pus showed an abundance of pus globules, but that of the interior did not show any. It was like a paste entirely composed of microbes, so numerous and fertile that, in less than six hours after sowing them in the cultivating liquid, the development of the little microbe had commenced, and was rendered visible to the naked eye by a slight but general turbidity of the liquid.

Its close resemblance to the organism of the boil might lead to the assertion that they are identical, if it were not known how great are the physiological differences that may exist between microscopic parasites of the same appearance and the same dimensions.