Chapter VII (2)

In a little notebook where he jotted down some intended experiments we find evidence of those glimpses of divination in a few summary lines: “Show that life is in the germ, that it has been but in a state of transmission since the origin of creation. That the germ possesses possibilities of development, either of intelligence and will, or--and in the same way--of physical organs. Compare these possibilities with those possessed by the germ of chemical species which is in the chemical molecule. The possibilities of development in the germ of the chemical molecule consist in crystallization, in its form, in its physical and chemical properties. Those properties are in power in the germ of the molecule in the same way as the organs and tissues of animals and plants are in their respective germs. Add: nothing is more curious than to carry the comparison of living species with mineral species into the study of the wounds of either, and of their healing by means of nutrition--a nutrition coming from within in living beings, and from without through the medium of crystallization in the others. Here detail facts....”

In that same notebook, Pasteur, after writing down the following heading, “Letter to prepare on the species in connection with molecular dissymmetry,” added, “I could write that letter to Bernard. I should say that being deprived of a laboratory by the present state of France, I am going to give him the preconceived ideas that I shall try to experiment upon when better times come. There is no peril in expressing ideas _a priori_, when they are taken as such, and can be gradually modified, perhaps even completely transformed, according to the result of the observation of facts.”

He once compared those preconceived ideas with searchlights guiding the experimentalist, saying that they only became dangerous when they became fixed ideas.

Civil war had now come, showing, as Renan said, “a sore under the sore, an abyss below the abyss.” What were the hopes and projects of Pasteur and of Sainte Claire Deville now that the very existence of the divided country was jeopardized under the eyes of the Prussians? The world of letters and of science, helpless amidst such disorders, had dispersed; Saint Claire Deville was at Gex, Dumas at Geneva. Some were wondering whether lectures could not be organized in Switzerland and in Belgium as they had been under the Empire, thus spreading abroad the influence of French thought. Examples might be quoted of men who had served the glory of their country in other lands, such as Descartes, who took refuge in Holland in order to continue his philosophic meditations. Pasteur might have been tempted to do likewise. Already, before the end of the war, an Italian professor of chemistry, Signor Chiozza, who had applied Pasteur’s methods to silkworms in the neighbourhood of Villa Vicentina, got the Italian Government to offer him a laboratory and the direction of a silkworm establishment. Pasteur refused, and a deputy of Pisa, Signor Toscanelli, hearing of this, obtained for Pasteur the offer of what was better still--a professor’s chair of Chemistry applied to Agriculture at Pisa; this would give every facility for work and all laboratory resources. “Pisa,” Signor Chiozza said, “is a quiet town, a sort of Latin quarter in the middle of the country, where professors and students form the greater part of the population. I think you would be received with the greatest cordiality and quite exceptional consideration ... I fear that black days of prolonged agitation are in store for France.”

Pasteur’s health and work were indeed valuable to the whole world, and Signor Chiozza’s proposition seemed simple and rational. Pasteur was much divided in his mind: his first impulse was to renew his refusal. He thought but of his vanquished country, and did not wish to forsake it. But was it to his country’s real interests that he should remain a helpless spectator of so many disasters? Was it not better to carry French teaching abroad, to try and provoke in young Italian students enthusiasm for French scientists, French achievements? He might still serve his beloved country in that quiet retreat, amidst all those facilities for continuous work. He thought of writing to Raulin, who had relations in Italy, and who might follow his master. Finally, he was offered very great personal advantages, a high salary--and this determined his refusal, for, as he wrote to Signor Chiozza, “I should feel that I deserved a deserter’s penalty if I sought, away from my country in distress, a material situation better than it can offer me.”

“Nevertheless allow me to tell you, Sir (he wrote to Signor Toscanelli, refusing his offer), in all sincerity, that the memory of your offer will remain in the annals of my family as a title of nobility, as a proof of Italy’s sympathy for France, as a token of the esteem accorded to my work. And as far as you, M. le Député, are concerned it will remain in my eyes a brilliant proof of the way in which public men in Italy regard science and its grandeur.”

And now what was Pasteur to do--he who could not live away from a laboratory? In April, 1871, he could neither go back to Paris and the Commune nor to Arbois, now transformed into a Prussian dépôt. It seemed, indeed, from the letters he received that his fellow citizens were now destined but to feed and serve a victorious foe, whose exactions were all the more rigorous that the invasion of the town on January 25 had been preceded by an attempt at resistance on the part of the inhabitants. On that morning, a few French soldiers who were seeking their regiments and a handful of _franc tireurs_ had posted themselves among the vines. About ten o’clock a first shot sounded in the distance; in a turn of the sinuous Besançon road, when the Prussian vanguard had appeared, a Zouave--who the day before was begging from door to door, shaking with ague, and who had taken refuge in the village of Montigny, two kilometres from Arbois--had in despair fired his last cartridge. A squad of Prussians left the road and rushed towards the smoke of the gun. The soldier was seized, shot down on the spot, and mutilated with bayonets. Whilst the main column continued their advance towards the town, detachments explored the vines on either side of the road, shooting here and there. An old man who, with a courageous indifference, was working in his vineyard was shot down at his work. A little pastrycook’s boy, nicknamed Biscuit by the Arboisians, who, led by curiosity; had come down from the upper town to the big poplar trees at the entrance of Arbois, suddenly staggered, struck by a Prussian bullet. He was just able to creep back to the first house, his eyes already dimmed by death.

Those were but the chances of war, but other crueller episodes thrilled Pasteur to the very depths of his soul. Such things are lost in history, just as a little blood spilt disappears in a river, but, for the witnesses and contemporaries of the facts, the trace of blood remains. An incident will help the reader to understand the lasting indignation the war excited in Pasteur.

One of the Prussian sergeants, who, after the shot fired at Montigny, were leading small detachments of soldiers, thought that a house on the outskirts of Arbois, in the faubourg of Verreux, looked as if it might shelter _franc tireurs_. He directed his men towards it and the house was soon reached.

It was now twelve o’clock, all fighting had ceased, and the first Prussians who had arrived were masters of the town. Others were arriving from various directions; a heavy silence reigned over the town. The mayor, M. Lefort, led by a Prussian officer who covered him with a revolver whenever he addressed him, was treated as a hostage responsible for absolute submission. Every door in the small Town Hall was opened in succession in order to see that there were no arms hidden. The mayor was each time made to pass first, so that he should receive the shot in case of a surprise. In the library, three flags, which General Delort had brought back from the Rhine campaign when he was a captain in the cavalry and given to his native town, were torn down and the general’s bust overturned.

The sergeant, violently entering the suspected house with his men, found a whole family peacefully sitting down to their dinner--the husband, wife, a son of nineteen, and two young daughters. The invaders made no search nor asked any questions of those poor people, who had probably done nothing worse than to offer a few glasses of wine to French soldiers as they passed. The sergeant did not even ask the name of the master of the house (Antoine Ducret, aged fifty-nine), but seized him by his coat and ordered his men to seize the son too. The woman, who rushed to the door in her endeavour to prevent her husband and her son from being thus taken from her, was violently flung to the end of the room, her trembling daughters crouching around her as they listened to the heavy Prussian boots going down the wooden stairs. There is a public drinking fountain not far from the house; Ducret was taken there and placed against a wall. He understood, and cried out, “Spare my son!!” “What do you say?” said the sergeant to the boy. “I will stay with my father,” he answered simply. The father, struck by two bullets at close range, fell at the feet of his son, who was shot down immediately afterwards. The two corpses, afterwards mutilated with bayonets, remained lying by the water side; the neighbours succeeded in preventing the mother and her two daughters from leaving their house until the bodies had been placed in a coffin. On the tombs of Antoine and Charles Ducret the equivocal inscription was placed “Fell at Arbois, January 25, 1871, under Prussian fire.” For the honour of humanity, a German officer, having heard these details, offered the life of the sergeant to Ducret’s widow; but she entertained no thoughts of revenge. “His death would not give them back to me,” she said.

Pasteur could not become resigned to the humiliation of France, and, tearing his thoughts from the nightmare of the war and the Commune, he dwelt continually on the efforts that would be necessary to carry out the great task of raising the country once again to its proper rank. In his mind it was the duty of every one to say, “In what way can I be useful?” Each man should strive not so much to play a great part as to give the best of his ability. He had no patience with those who doubt everything in order to have an excuse for doing nothing.

He had indeed known dark moments of doubt and misgivings, as even the greatest minds must do, but notwithstanding these periods of discouragement he was convinced that science and peace will ultimately triumph over ignorance and war. In spite of recent events, the bitter conditions of peace which tore unwilling Alsace and part of Lorraine away from France, the heavy tax of gold and of blood weighing down future generations, the sad visions of young men in their prime cut down on the battlefield or breathing their last in hospitals all to no apparent purpose; in spite of all these sad memories he was persuaded that thinkers would gradually awaken in the nations ideas of justice and of concord.

He had now for nine years been following with a passionate interest some work begun in his own laboratory by Raulin, his first curator. Some of the letters he wrote to Raulin during those nine years give us a faint idea of the master that Pasteur was. It had been with great regret that Raulin had left the laboratory in obedience to the then laws of the University in order to take up active work at the Brest college, and Pasteur’s letters (December, 1862) brought him joy and encouragement: “Keep up your courage, do not allow the idleness of provincial life to disturb you. Teach your pupils to the very best of your ability and give up your leisure to experiments; this was M. Biot’s advice to myself.” When in July, 1863, he began to fear that Raulin might allow imagination to lead him astray in his work, he repeatedly advised him to state nothing that could not be proved: “Be very strict in your deductions”; then, apparently, loth to damp the young man’s ardour: “I have the greatest confidence in your judgment; do not take too much heed of my observations.”

In 1863 Pasteur asked Raulin to come with him, Gernez and Duclaux, to Arbois for some studies on wines, etc., but Raulin, absorbed in the investigations he had undertaken, refused; in 1865 he refused to come to Alais, still being completely wrapt up in the same work. Pasteur sympathized heartily with his pupil’s perseverance, and, when Raulin was at last able to announce to his master the results so long sought after, Pasteur hurried to Caen, where Raulin was now professor of Physics, and returned full of enthusiasm. His modesty in all that concerned himself now giving way to delighted pride, he spoke of Raulin’s discoveries to every one. Yet they concerned an apparently unimportant subject--a microscopical fungus, a simple mucor, whose spores, mingled with atmospheric germs, develop on bread moistened with vinegar or on a slice of lemon; yet no precious plant ever inspired more care or solicitude than that _aspergillus niger_, as it is called. Raulin, inspired by Pasteur’s studies on cultures in an artificial medium, that is, a medium exclusively composed of defined chemical substances, resolved to find for this plant a typical medium capable of giving its maximum development to the aspergillus niger. Some of his comrades looked upon this as upon a sort of laboratory amusement; but Raulin, ever a man of one idea, looked upon the culture of microscopic vegetation as a step towards a greater knowledge of vegetable physiology, leading to the development of artificial manure production, and from that to the rational nutrition of the human organisms. He started from the conditions indicated by Pasteur for the development of mucedinæ in general and in particular for a mucor which has some points of resemblance with the aspergillus niger, the _penicillium glaucum_, which spreads a bluish tint over mouldy bread, jam, and soft cheeses. Raulin began by placing pure spores of aspergillus niger on the surface of a saucer containing everything that seemed necessary to their perfect growth, in a stove heated to a temperature of 20°C.; but in spite of every care, after forty days had passed, the tiny fungus was languishing and unhealthy. A temperature of 30° did not seem more successful; and when the stove was heated to above 38° the result was the same. At 35°, with a moist and changing atmosphere, the result was favourable--very fortunately for Raulin, for the principal of the college, an economically minded man, did not approve of burning so much gas for such a tiny fungus and with such poor results. This want of sympathy excited Raulin’s solemn wrath and caused him to meditate dark projects of revenge, such as ignoring his enemy in the street on some future occasion. In the meanwhile he continued his slow and careful experiments. He succeeded at last in composing a liquid, technically called Raulin’s liquid, in which the aspergillus niger grew and flourished within six or even three days. Eleven substances were necessary: water, candied sugar, tartaric acid, nitrate of ammonia, phosphate of ammonia, carbonate of potash, carbonate of magnesia, sulphate of ammonia, sulphate of zinc, sulphate of iron, and silicate of potash. He now studied the part played by each of those elements, varying his quantities, taking away one substance and adding another, and obtained some very curious results. For instance, the aspergillus was extraordinarily sensitive to the action of zinc; if the quantity of zinc was reduced by a few milligrams the vegetation decreased by one-tenth. Other elements were pernicious; if Raulin added to his liquid 1/1600000 of nitrate of silver, the growth of the fungus ceased. Moreover, if he placed the liquid in a silver goblet instead of a china saucer, the vegetation did not even begin, “though,” writes M. Duclaux, analysing this fine work of his fellow student, “it is almost impossible to chemically detect any dissolution of the silver into the liquid. But the fungus proves it by dying.”

In this thesis, now a classic, which only appeared in 1870, Raulin enumerated with joyful gratitude all that he owed to his illustrious master--general views, principles and methods, suggestive ideas, advice and encouragement--saying that Pasteur had shown him the road on which he had travelled so far. Pasteur, touched by his pupil’s affection, wrote to thank him, saying: “You credit me with too much; it is enough for me that your work should be known as having been begun in my laboratory, and in a direction the fruitfulness of which I was perhaps the first to point out. I had only conceived hopes, and you bring us solid realities.”

In April, 1871, Pasteur, preoccupied with the future, and ambitious for those who might come after him, wrote to Claude Bernard: “Allow me to submit to you an idea which has occurred to me, that of conferring on my dear pupil and friend Raulin the Experimental Physiology prize, for his splendid work on the nutriment of mucors, or rather of a mucor, the excellence of which work has not escaped you. I doubt if you can find anything better. I must tell you that this idea occurred to me whilst reading your admirable report on the progress of General Physiology in France. If therefore my suggestion seems to you acceptable, you will have sown the germ of it in my mind; if you disapprove of it I shall make you partly responsible.”

Claude Bernard hastened to reply: “You may depend upon my support for your pupil M. Raulin. It will be for me both a pleasure and a duty to support such excellent work and to glorify the method of the master who inspired it.”

In his letter to Claude Bernard, Pasteur had added these words: “I have made up my mind to go and spend a few months at Royat with my family, so as to be near my dear Duclaux. We shall raise a few grammes of silkworm seed.”

M. Duclaux was then professor of chemistry at the Faculty of Clermont Ferrand, a short distance from Royat, and Pasteur intended to walk every day to the laboratory of his former pupil. But M. Duclaux did not countenance this plan; he meant to entertain his master and his master’s family in his own house, 25, Rue Montlosier, where he could even have one room arranged as a silkworm nursery. He succeeded in persuading Pasteur, and they organized a delightful home life which recalled the days at Pont Gisquet before the war.

Pasteur was seeking the means of making his seed-selecting process applicable to small private nurseries as well as to large industrial establishments. The only difficulty was the cost of the indispensable microscope; but Pasteur thought that each village might possess its microscope, and that the village schoolmaster might be entrusted with the examination of the moths.

In a letter written in April, 1871, to M. Bellotti, of the Milan Civic Museum, Pasteur, after describing in a few lines the simple process he had taken five years to study, added--

“If I dared to quote myself, I would recall those words from my book--

“‘If I were a silkworm cultivator I never would raise seed from worms I had not observed during the last days of their life, so as to satisfy myself as to their vigour and agility just before spinning. The seed chosen should be that which comes from worms who climbed the twigs with agility, who showed no mortality from flachery between the fourth moulting and climbing time, and whose freedom from corpuscles will have been demonstrated by the microscope. If that is done, any one with the slightest knowledge of silkworm culture will succeed in every case.’”

Italy and Austria vied with each other in adopting the seed selected by the Pasteur system. But it was only when Pasteur was on the eve of receiving from the Austrian Government the great prize offered in 1868 to “whoever should discover a preventive and curative remedy against pébrine” that French sericicultors began to be convinced. The French character offers this strange contrast, that France is often willing to risk her fortune and her blood for causes which may be unworthy, whilst at another moment, in everyday life, she shrinks at the least innovation before accepting a benefit originated on her own soil. The French often wait until other nations have adopted and approved a French discovery before venturing to adopt it in their turn.

Pasteur did not stop to look back and delight in his success, but hastened to turn his mind to another kind of study. His choice of a subject was influenced by patriotic motives. Germany was incontestably superior to France in the manufacture of beer, and he conceived the thought of making France a successful rival in that respect; in order to enable himself to do so, he undertook to study the scientific mechanism of beer manufacture.

There was a brewery at Chamalières, between Clermont and Royat. Pasteur began by visiting it with eager curiosity, inquiring into the minutest details, endeavouring to find out the why and the wherefore of every process, and receiving vague answers with much astonishment. M. Kuhn, the Chamalières brewer, did not know much more about beer than did his fellow brewers in general. Very little was known at that time about the way it was produced; when brewers received complaints from their customers, they procured yeast from a fresh source. In a book of reference which was then much in use, entitled _Alimentary Substances: the Means of Improving and Preserving them, and of Recognizing their Alterations_, six pages were given up to beer by the author, M. Payen, a member of the Institute. He merely showed that germinated barley, called malt, was diluted, then heated and mixed with hops, thus forming beer-wort, which was submitted, when cold, to alcoholic fermentation through the yeast added to the above liquid. M. Payen conceded to beer some nutritive properties, but added, a little disdainfully, “Beer, perhaps on account of the pungent smell of hops, does not seem endowed with stimulating properties as agreeable, or as likely to inspire such bright and cheerful ideas, as the sweet and varied aroma of the good wines of France.”

In a paragraph on the alterations of beer--“_spontaneous_ alterations”--M. Payen said that it was chiefly during the summer that beer became altered. “It becomes acid, and even noticeably putrid, and ceases to be fit to drink.”

Pasteur’s hopes of making French beer capable of competing with German beer were much strengthened by faith in his own method. He had, by experimental proof, destroyed the theory of spontaneous generation; he had shown that chance has no share in fermentations; the animated nature and the specific characteristics of those ferments, the methods of culture in appropriate media, were so many scientific points gained. The difficulties which remained to be solved were the question of pure yeast and the search for the causes of alteration which make beer thick, acid, sour, slimy or putrid. Pasteur thought that these alterations were probably due to the development of germs in the air, in the water, or on the surface of the numerous utensils used in a brewery.

As he advanced further and further into that domain of the infinitely small which he had discovered, whether the subject was wine, vinegar, or silkworms--this last study already opening before him glimpses of light on human pathology--new and unexpected visions rose before his sight.

Pasteur had formerly demonstrated that if a putrescible liquid, such as beef broth for instance, after being previously boiled, is kept in a vessel with a long curved neck, the air only reaching it after having deposited its germs in the curves of the neck, does not alter it in any way. He now desired to invent an apparatus which would protect the wort against external dusts, against the microscopic germs ever ready to interfere with the course of proper fermentation by the introduction of other noxious ferments. It was necessary to prove that beer remains unalterable whenever it does not contain the organisms which cause its diseases. Many technical difficulties were in the way, but the brewers of Chamalières tried in the most obliging manner to facilitate things for him.

This exchange of services between science and industry was in accordance with Pasteur’s plan; though he had been prophesying for fourteen years the great progress which would result from an alliance between laboratories and factories, the idea was hardly understood at that time. Yet the manufacturers of Lille and Orleans, the wine merchants and the silkworm cultivators of the South of France, and of Austria and Italy, might well have been called as enthusiastic witnesses to the advantages of such a collaboration.

Pasteur, happy to make the fortune of others, intended to organize, against the danger of alterations in beer, some experiments which would give to that industry solid notions resting on a scientific basis. “Dear master,” wrote he to J. B. Dumas on August 4, 1871, from Clermont, “I have asked the brewer to send you twelve bottles of my beer.... I hope you will find it compares favourably even with the excellent beer of Paris cafés.” There was a postscript to this letter, proving once more Pasteur’s solicitude for his pupils. “A thousand thanks for your kind welcome of Raulin’s work; Bernard’s support has also been promised him. The Academy could not find a better recipient for the prize. It is quite exceptional work.”

Pasteur, ever full of praises for his pupil, also found excuses for him. In spite of M. Duclaux’s pressing request, Raulin had again found reasons to refuse an invitation to come to Auvergne for a few days. “I regret very much that you did not come to see us,” wrote Pasteur to Raulin, “especially on account of the beer.... Tell me what you think of doing. When are you coming to Paris for good? I shall want you to help me to arrange my laboratory, where everything, as you know, has still to be done; it must be put into working order as soon as possible.”

Pasteur would have liked Raulin to come with him to London in September, 1871, before settling down in Paris.

The Chamalières brewery was no longer sufficient for Pasteur; he wished to see one of those great English breweries which produce in one year more than 100,000 hectolitres of beer. The great French _savant_ was most courteously received by the managers of one of the most important breweries in London, who offered to show him round the works where 250 men were employed. But Pasteur asked for a little of the barm of the porter which was flowing into a trough from the cask. He examined that yeast with a microscope, and soon recognized a noxious ferment which he drew on a piece of paper and showed to the bystanders, saying, “This porter must leave much to be desired,” to the astonished managers, who had not expected this sudden criticism. Pasteur added that surely the defect must have been betrayed by a bad taste, perhaps already complained of by some customers. Thereupon the managers owned that that very morning some fresh yeast had had to be procured from another brewery. Pasteur asked to see the new yeast, and found it incomparably purer, but such was not the case with the barm of the other products then in fermentation--_ale_ and _pale ale_.

By degrees, samples of every kind of beer on the premises were brought to Pasteur and put under the microscope. He detected marked beginnings of disease in some, in others merely a trace, but a threatening one. The various foremen were sent for; this scientific visit seemed like a police inquiry. The owner of the brewery, who had been fetched, was obliged to register, one after another, these experimental demonstrations. It was only human to show a little surprise, perhaps a little impatience of wounded feeling. But it was impossible to mistake the authority of the French scientist’s words: “Every marked alteration in the quality of the beer coincides with the development of micro-organisms foreign to the nature of true beer yeast.” It would have been interesting to a psychologist to study in the expression of Pasteur’s hearers those shades of curiosity, doubt, and approbation, which ended in the thoroughly English conclusion that there was profit to be made out of this object lesson.

Pasteur afterwards remembered with a smile the answers he received, rather vague at first, then clearer, and, finally--interest and confidence now obtained--the confession that there was in a corner of the brewery a quantity of spoilt beer, which had gone wrong only a fortnight after it was made, and was not drinkable. “I examined it with a microscope,” said Pasteur, “and could not at first detect any ferments of disease; but guessing that it might have become clear through a long rest, the ferments now inert having dropped to the bottom of the reservoirs, I examined the deposit at the bottom of the reservoirs. It was entirely composed of filaments of disease unmixed with the least globule of alcoholic yeast. The complementary fermentation of that beer had therefore been exclusively a morbid fermentation.”

When he visited the same brewery again, a week later, he found that not only had a microscope been procured immediately, but the yeast of all the beer then being brewed had been changed.

Pasteur was happy to offer to the English, who like to call themselves practical men, a proof of the usefulness of disinterested science, persuaded as he was that the moral debt incurred to a French scientist would in some measure revert to France herself. “We must make some friends for our beloved France,” he would say. And if in the course of conversation an Englishman gave expression to any doubt concerning the future of the country, Pasteur, his grave and powerful face full of energy, would answer that every Frenchman, after the horrible storm which had raged for so many months, was valiantly returning to his daily task, whether great or humble, each one thinking of retrieving the national fall.

Every morning, as he left his hotel to go to the various breweries which he was now privileged to visit in their smallest details, he observed this English people, knowing the value of time, seeing its own interests in all things, consistent in its ideas and in its efforts, respectful of established institutions and hierarchy; and he thought with regret how his own countrymen lacked these qualities. But if the French are rightly taxed with a feverish love of change, should not justice be rendered to that generous side of the French character, so gifted, capable of so much, and which finds in self-sacrifice the secret of energy, for whom hatred is a real suffering? “Let us work!” Pasteur’s favourite phrase ever ended those philosophical discussions.

He wanted to do two years’ work in one, regardless of health and strength. Beyond the diseases of beer, avoidable since they come from outside, he foresaw the application of the doctrine of exterior germs to other diseases. But he did not allow his imagination to run away with him, and resolutely fixed his mind on his present object, which was the application of science to the brewing industry.

“The interest of those visits to English breweries,” wrote Pasteur to Raulin, “and of the information I am able to collect (I hear that I ought to consider this as a great favour) causes me to regret very much that you should be in want of rest, for I am sure you would have been charmed to acquire so much instruction _de visu_. Why should you not come for a day or two if your health permits? Do as you like about that, but in any case prepare for immediate work on my return. We need not wait for the new laboratory; we can settle down in the old one and in a Paris brewery.”

When Pasteur returned to Paris, Bertin, who had not seen him since the recent historic events, welcomed him with a radiant delight. School friendships are like those favourite books which always open at the page we prefer; time has no hold on certain affections; ever new, ever young, they never show signs of age. Bertin’s love was very precious to Pasteur, though the two friends were as different from each other as possible. Pasteur, ever preoccupied, seemed to justify the Englishman who said that genius consists in an infinite capacity for taking pains; whilst Bertin, with his merry eyes, was the very image of a smiling philosopher. In spite of his position as sub-director, which he most conscientiously filled, he was not afraid to whistle or to sing popular songs as he went along the passages of the Ecole Normale. He came round to Pasteur’s rooms almost every evening, bringing with him joy, lightness of heart, and a rest and relaxation for the mind, brightening up his friend by his amusing way of looking at things in general, and--at that time--beer in particular.

Whilst Pasteur saw but pure yeast, and thought but of spores of disease, ferments, and parasitic invasions, Bertin would dilate on certain cafés in the Latin quarter, where, without regard to great scientific principles, experts could be asked to pronounce between the beer on the premises and laboratory beer, harmless and almost agreeable, but lacking in the refinement of taste of which Bertin, who had spent many years in Strasburg, was a competent judge. Pasteur, accustomed to an absolutely infallible method, like that which he had invented for the seeding of silkworms, heard Bertin say to him, “First of all, give me a good _bock_, you can talk learnedly afterwards.” Pasteur acknowledged, however, the improvements obtained by certain brewers, who, thanks to the experience of years, knew how to choose yeast which gave a particular taste, and also how to employ preventive measures against accidental and pernicious ferments (such as the use of ice, or of hops in a larger quantity). But, though laughing at Bertin’s jokes, Pasteur was convinced that great progress in the brewer’s art would date from his studies.

He was now going through a series of experiments, buying at Bertin’s much praised cafés samples of various famous beers--Strasburg, Nancy, Vienna, Burton’s, etc. After letting the samples rest for twenty-four hours he decanted them and sowed one drop of the deposit in vessels full of pure wort, which he placed in a temperature of 20° C. After fifteen or eighteen days he studied and tasted the yeasts formed in the wort, and found them all to contain ferments of diseases. He sowed some pure yeast in some other vessels, with the same precautions, and all the beers of this series remained pure from strange ferments and free from bad taste; they had merely become _flat_.

He was eagerly seeking the means of judging how his laboratory tests would work in practice. He spent some time at Tantonville, in Lorraine, visiting an immense brewery, of which the owners were the brothers Tourtel. Though very carefully kept, the brewery was yet not quite clean enough to satisfy him. It is true that he was more than difficult to please in that respect; a small detail of his everyday life revealed this constant preoccupation. He never used a plate or a glass without examining them minutely and wiping them carefully; no microscopic speck of dust escaped his short-sighted eyes. Whether at home or with strangers he invariably went through this preliminary exercise, in spite of the anxious astonishment of his hostess, who usually feared that some negligence had occurred, until Pasteur, noticing her slight dismay, assured her that this was but an inveterate scientist’s habit. If he carried such minute care into daily life, we can imagine how strict was his examination of scientific things and of brewery tanks.

After those studies at Tantonville with his curator, M. Grenet, Pasteur laid down three great principles--

1. Every alteration either of the wort or of the beer itself depends on the development of micro-organisms which are ferments of diseases.

2. These germs of ferments are brought by the air, by the ingredients, or by the apparatus used in breweries.

3. Whenever beer contains no living germs it is unalterable.

When once those principles were formulated and proved they were to triumph over all professional uncertainties. And in the same way that wines could be preserved from various causes of alteration by heating, bottled beer could escape the development of disease ferments by being brought to a temperature of 50° to 55°. The application of this process gave rise to the new word “_pasteurized_” beer, a neologism which soon became current in technical language.

Pasteur foresaw the distant consequences of these studies, and wrote in his book on beer--

“When we see beer and wine subjected to deep alterations because they have given refuge to micro-organisms invisibly introduced and now swarming within them, it is impossible not to be pursued by the thought that similar facts may, _must_, take place in animals and in man. But if we are inclined to believe that it is so because we think it likely and possible, let us endeavour to remember, before we affirm it, that the greatest disorder of the mind is to allow the will to direct the belief.”

This shows us once more the strange duality of this inspired man, who associated in his person the faith of an apostle with the inquiring patience of a scientist.

He was often disturbed by tiresome discussions from the researches to which he would gladly have given his whole time. The heterogenists had not surrendered; they would not admit that alterable organic liquids could be indefinitely preserved from putrefaction and fermentation when in contact with air freed from dusts.

Pouchet, the most celebrated of them, who considered that part of a scientist’s duty consists in vulgarizing his discoveries, was preparing for the New Year, 1872, a book called _The Universe: the Infinitely Great and the Infinitely Small_. He enthusiastically recalled the spectacle revealed at the end of the seventeenth century by the microscope, which he compared to a sixth sense. He praised the discoveries made in 1838 by Ehrenberg on the prodigious activity of infusories, but he never mentioned Pasteur’s name, leaving entirely on one side the immense work accomplished by the infinitely small and ever active agents of putrefaction and fermentation. He owned that “a few microzoa did fly about here and there,” but he called the theory of germs a “ridiculous fiction.”

At the same time Liebig, who, since the interview in July, 1870, had had time to recover his health, published a long treatise disputing certain facts put forward by Pasteur.

Pasteur had declared that, in the process of vinegar-making known as the German process, the chips of beech-wood placed in the barrels were but supports for the _mycoderma aceti_. Liebig, after having, he said, consulted at Munich the chief of one of the largest vinegar factories, who did not believe in the presence of the mycoderma, affirmed that he himself had not seen a trace of the fungus on chips which had been used in that factory for twenty-five years.

In order to bring this debate to a conclusion Pasteur suggested a very simple experiment, which was to dry some of those chips rapidly in a stove and to send them to Paris, where a commission, selected from the members of the Académie des Sciences, would decide on this conflict. Pasteur undertook to demonstrate to the Commission the presence of the mycoderma on the surface of the chips. Or another means might be used: the Munich vinegar maker would be asked to scald one of his barrels with boiling water and then to make use of it again. “According to Liebig’s theory,” said Pasteur, “that barrel should work as before, but I affirm that no vinegar will form in it for a long time, not until new mycoderma have grown on the surface of the chips.” In effect, the boiling water would destroy the little fungus. With the usual clear directness which increased the interest of the public in this scientific discussion, Pasteur formulated once more his complete theory of acetification: “The principle is very simple: whenever wine is transformed into vinegar, it is by the action of the layer of _mycoderma aceti_ developed on its surface.” Liebig, however, refused the suggested test.

Immediately after that episode a fresh adversary, M. Frémy, a member of the Académie des Sciences, began with Pasteur a discussion, which was destined to be a long one, on the question of the origin of ferments. M. Frémy alluded to the fact that he had given many years to that subject, having published a notice on lactic fermentation as far back as 1841, “at a time,” he said, “when our learned colleague--M. Pasteur--was barely entering into science.”... “In the production of wine,” said M. Frémy, “it is the juice of the fruit itself, which, put in contact with air, gives birth to grains of yeast by the transformation of albuminous matter, whilst M. Pasteur declares that the grains of yeast are produced by germs.” According to M. Frémy, ferments did not come from atmospheric dusts, but were created by organic bodies. And, inventing for his own use the new word _hemiorganism_, M. Frémy explained the word and the action by saying that there are some _hemiorganized_ bodies which, by reason of the vital force with which they are endowed, go through successive decompositions and give birth to new derivatives; thus are ferments engendered.

Another colleague, M. Trécul, a botanist and a genuine truth-seeking _savant_, arose in his turn. He said he had witnessed a whole transformation of microscopic species each into the other, and in support of this theory he invoked the names of the three inseparables--Pouchet, Musset and Joly. Himself a heterogenist, he had in 1867 given a definition to which he willingly alluded: “Heterogenesis is a natural operation by which life, on the point of abandoning an organized body, concentrates its action on some particles of that body and forms thereof beings quite different from that of the substance which has been borrowed.”

Old arguments and renewed negations were brought forward, and Pasteur knew well that this was but a reappearance of the old quarrel; he therefore answered by going straight to the point. At the Académie des Sciences, on December 26, 1871, he addressed M. Trécul in these words: “I can assure our learned colleague that he might have found in the treatises I have published decisive answers to most of the questions he has raised. I am really surprised to see him tackle the question of so-called spontaneous generation, without having more at his disposal than doubtful facts and incomplete observations. My astonishment was not less than at our last sitting, when M. Frémy entered upon the same debate with nothing to produce but superannuated opinions and not one new positive fact.”

In his passion for truth and his desire to be convincing Pasteur threw out this challenge: “Would M. Frémy confess his error if I were to demonstrate to him that the natural juice of the grape, exposed to the contact of air, deprived of its germs, can neither ferment nor give birth to organized yeasts?” This interpellation was perhaps more violent than was usual in the meetings of the solemn Academy, but scientific truth was in question. And Pasteur, recognizing the old arguments under M. Frémy’s hemiorganism and M. Trécul’s transformations, referred his two contradictors to the experiments by which he had proved that alterable liquids, such as blood or urine, could be exposed to the contact of air deprived of its germs without undergoing the least fermentation or putrefaction. Had not this fact been the basis on which Lister had founded “his marvellous surgical method”? And in the bitterness given to his speech by his irritation against error, the epithet “marvellous” burst out with a visible delight in rendering homage to Lister.

Pasteur, then in full possession of all the qualities of his genius, was feeling the sort of fever known to great scientists, great artists, great writers: the ardent desire of finding, of discovering something he could leave to posterity. Interrupted by these belated contradictors when he wanted to be going forward, he only restrained his impatience with difficulty.

His old master, Balard, appealed to him in the Académie itself (January 22, 1872), in the name of their old friendship, to disregard the attacks of his adversaries, instead of wasting his time and his strength in trying to convince them. He reminded him of all he had achieved, of the benefits he had brought to the industries of wine, beer, vinegar, silkworms, etc., and alluded to the possibility foreseen by Pasteur himself of preserving mankind from some of the mysterious diseases which were perhaps due to germs in atmospheric air. He ended by urging him to continue his studies peacefully in the laboratory built for him, and to continue the scientific education of young pupils who might one day become worthy successors of Van Tieghem, Duclaux, Gernez, Raulin, etc.... thus forming a whole generation of young scientists instructed in Pasteur’s school.

M. Duclaux wrote to him in the same sense: “I see very well what you may lose in that fruitless struggle--your rest, your time and your health; I try in vain to see any possible advantage.”

But nothing stopped him; neither Balard’s public advice, his pupils’ letters, even J. B. Dumas’ imploring looks. He could not keep himself from replying. Sometimes he regretted his somewhat sharp language, though--in his own words--he never associated it with feelings of hostility towards his contradictors as long as he believed in their good faith; what he wanted was that truth should have the last word. “What _you_ lack, M. Frémy, is familiarity with a microscope, and you, M. Trécul, are not accustomed to laboratories!” “M. Frémy is always trying to displace the question,” said Pasteur, ten months after M. Balard’s appeal.

Whilst M. Frémy disputed, discussed, and filled the Académie with his objections, M. Trécul, whose life was somewhat misanthropical and whose usually sad and distrustful face was seen nowhere but at the Institute, insisted slowly, in a mournful voice, on certain transformations of divers cells or spores from one into the other. Pasteur declared that those ideas of transformation were erroneous; but--and there lay the interest of the debate--there was one of those transformations that Pasteur himself had once believed possible: that of the _mycoderma vini_, or wine flower, into an alcoholic ferment under certain conditions of existence.

A modification in the life of the mycoderma when submerged had led him to believe in a transformation of the mycoderma cells into yeast cells. It was on this question, which had been left in suspense, that the debate with Trécul came to an end, leaving to the witnesses of it a most vivid memory of Pasteur’s personality--inflexible when he held his proofs, full of scruples and reserve when seeking those proofs, and accepting no personal praise if scientific truth was not recognized and honoured before everything else.

On November 11 Pasteur said: “Four months ago doubts suddenly appeared in my mind as to the truth of the fact in question, and which M. Trécul still looks upon as indisputable.... In order to disperse those doubts I have instituted the most numerous and varied experiments and I have not succeeded through those four months in satisfying myself by irrefragable proofs; I still have my doubts. Let this example show to M. Trécul how difficult it is to conclude definitely in such delicate studies.”

Pasteur studied the scientific point for a long time, for he never abandoned a subject, but was ever ready to begin again after a failure. He modified the disposition of his first tests, and by the use of special vessels and slightly complicated apparatus succeeded in eliminating the only imaginable cause of error--the possible fall, during the manipulations, of exterior germs, that is, the fortuitous sowing of yeast cells. After that he saw no more yeast and no more active alcoholic fermentation; he had therefore formerly been the dupe of a delusion. In his _Studies on Beer_ Pasteur tells of his error and its rectification: “At a time when ideas on the transformations of species are so readily adopted, perhaps because they dispense with rigorous experimentation, it is somewhat interesting to consider that in the course of my researches on microscopic plants in a state of purity I once had occasion to believe in the transformation of one organism into another, the transformation of the _mycoderma vini_ or _cerevisiae_ into yeast, and that this time I was in error; I had not avoided the cause of illusion which my confirmed confidence in the theory of germs had so often led me to discover in the observations of others.”

“The notion of species,” writes M. Duclaux, who was narrowly associated with those experiments, “was saved for the present from the attacks directed against it, and it has not been seriously contested since, at least not on that ground.”

Some failures are blessings in disguise. When discovering his mistake, Pasteur directed his attention to a strange phenomenon. We find in his book on beer--a sort of laboratory diary--the following details on his observation of the growth of some mycoderma seed which he had just scattered over some sweetened wine or beer-wort in small china saucers.

“When the cells or articles of the mycoderma vini are in full germinating and propagating activity in contact with air on a sweetened substratum, they live at the expense of that sugar and other subjacent materials absolutely like the animals who also utilize the oxygen in the air while freeing carbonic acid gas, consuming this and that, and correlatively increasing, regenerating themselves and creating new materials.

“Under those conditions not only does the mycoderma vini form no alcohol appreciable by analysis, but if alcohol exists in the subjacent liquid the mycoderma reduces it to water and carbonic acid gas by the fixation of the oxygen in the air.” Pasteur, having submerged the mycoderma and studied it to see how it would accommodate itself to the new conditions offered to it, and whether it would die like an animal asphyxiated by the sudden deprivation of oxygen, saw that life was continued in the submerged cells, slow, difficult, of a short duration, but undoubtedly life, and that this life was accompanied by alcoholic fermentation. This time fermentation was due to the fungus itself. The mycoderma, originally an aërobia--that is, a being to the life and development of which air was necessary--became, after being submerged, an anaërobia, that is, a creature living without air in the depths of the liquid, and behaving after the manner of ferments.

This extended the notions on aërobiæ and anaërobiæ which Pasteur had formerly discovered whilst making researches concerning the vibrio which is the butyric ferment, and those vibriones which are entrusted with the special fermentation known as putrefaction. Between the aërobiæ who require air to live and the anaërobiæ which perish when exposed to air, there was a class of organisms capable of living for a time outside the influence of air. No one had thought of studying the mouldiness which develops so easily when in contact with air; Pasteur was curious to see what became of it when submitted like the mycoderma to that unexpected _régime_. He saw the penicillium, the aspergillus, the mucor-mucedo take the character of ferments when living without air, or with a quantity of air too small to surround their organs as completely as was necessary to their aërobia-plant life. The mucor, when submerged and thus forced to become an anaërobia, offers budding cells, and there again it seemed as if they were yeast globules. “But,” said Pasteur, “this change of form merely corresponds to a change of function, it is but a self-adaptation to the new life of an anaërobia.” And then, generalizing again and seeking for laws under the accumulation of isolated facts, he thought it probable that ferments had, “but in a higher degree, a character common to most mucors if not to all, and probably possessed more or less by all living cells, viz., to be alternately aërobic or anaërobic, according to conditions of environment.”

Fermentation, therefore, no longer appeared as an isolated and mysterious act; it was a general phenomenon, subordinate however to the small number of substances capable of a decomposition accompanied by a production of heat and of being used for the alimentation of inferior beings outside the presence and action of air. Pasteur put the whole theory into this concise formula, “Fermentation is life without air.”

“It will be seen,” wrote M. Duclaux, “to what heights he had raised the debate; by changing the mode of interpretation of known facts he brought out a new theory.”