About the middle of his career Bernard suffered from a succession of attacks of a mysterious malady that we now recognize to have been appendicitis. Once at least his life was despaired of, and recurring attacks made life miserable. After a year of enforced rest on the old farm of his boyhood, now become his own, he seems to have recovered more or less completely. His health, however, was never so robust as before. Toward the end of his life he lived alone. His wife and daughters were separated from him, and one of the daughters devoted her time and means to suffering animals in order to make up, as she proclaimed, for all her father"s cruelty.

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Bernard lived almost directly opposite to the College de France, in a small apartment in the rue des Ecoles. An old family servant took care of him, and his life was one of uttermost simplicity, devoted only to science. Once at court, in 1869, Napoleon III insisted on knowing, after an hour"s conversation with him, what he could do for him.

Bernard asked only for new facilities for his experimental work, and new apparatus and s.p.a.ce for his laboratory.

Honors came to him, but left him modest as before. He was elected a member of the French Academy--one of the forty immortals. Only five times in the history of the Academy has the honor of membership been conferred upon a medical man. Before Bernard, Flourens, the father of brain physiology, had occupied a _fauteuil_, while Cabanis and Vicq d"Azyr are two other names of medical immortals.

Bernard was elected to the 24th _fauteuil_, which had been occupied by Flourens, and according to custom had to p.r.o.nounce his predecessor"s panegyric. The conclusion of his address was the expression: "There is no longer a line of demarcation between physiology and psychology."

Physiology had become the all-ruler for Bernard in human function, and he drifted into what would have been simple materialism only for the saving grace of his own utter sanity, his active imagination, and the unconscious influence of early training. During his most successful years of scientific investigation, wrapped up in his experiments and their suggestions, Bernard was drawn far away from the spiritual side of things. This partial view of man and nature could not endure, however. In an article on Bernard in the _Revue des Questions scientifiques_ for April, 1880, Father G. Hahn, S. J., says of him: "A man of such uprightness of character could not be allowed to persist to the end in this restless skepticism. His mental condition was really a kind of vertigo caused by the {287} depths of nature that he saw all around him. At the threshold of eternity he came back to his true self and his good sense triumphed. The great physiologist died a true Christian."

Bernard was one of the great thinkers of an age whose progress in science will stamp it as one of the most successful periods of advance in human thought. He accomplished much, but much more he seemed to have divined. He seldom gave out the slightest hint of the tendencies of his mind, or of his expectations of discovery in matters of science, until fully satisfied that his theoretic considerations were justified and confirmed by observation and experiment. In one thing, however, he allowed favored friends to share some of his antic.i.p.ations, and the notes published after his death show that he was on the very point of another great discovery in biology which has since been made. He was a firm friend of Pasteur"s, and had ably seconded the great chemist-biologist"s efforts to disprove spontaneous generation. Bernard"s demonstration that air pa.s.sed through a tube heated red hot might be suffered with impunity to come in contact with any sort of organic material, yet would never cause the development of germ life, was an important link in the proof that if life were carefully destroyed, no life, however microscopic in character, would develop unless the seeds of previously existent life were somehow brought in contact with the organic matter.

With regard to fermentation, too, Bernard was for many years in close accord with Pasteur, who taught that fermentation was the result of the chemical activity of living cells, the ferments. Toward the end of his life Bernard came to the view, however, that the action of ferments was really due to the presence in them of chemically active substances called diastases. These substances are of varied chemical {288} composition, but each one has a constant formula. Their presence in a fermentescible solution is sufficient of itself, even in the absence of living cells, to bring about fermentation. It has since been shown that after this substance is removed from ferment-cells by pressure, and the liquid carefully filtered so that absolutely no cells remain, fermentation will yet take place.

This does not disprove the necessity for life to produce the diastases originally, though it advances science a step beyond the theory that it is the actual vital interchange of nutritious substances within the ferment-cell that causes fermentation. With each step of advance in biological science the mystery of life and its processes deepens.

No one has done more to bring out the depths there are in vital function than Bernard. His early training was of the type that is, according to many prominent educators of our day, least calculated to develop originality of view, or capacity for initiating new lines of thought. Our pedagogic Solons would claim that the narrow orthodoxy that wrapped itself around his developmental years must surely stifle the precious genius for investigation that was in him. It is due, on the contrary, very probably to the thorough conservatism of his early training and the rounded fulness of the mental development acquired under the old system of cla.s.sical education, that we have to chronicle of Bernard none of the errors by exaggeration of personal bias that are so common among even great scientific men. Few successful men have ever owed less to luck or to favoring circ.u.mstances in life. He was in the best sense a self-made man, and he owed his success to a large liberality of mind that enabled him to grasp things in their true proportions. With an imaginative faculty that constantly outstripped his experimental observations he was singularly free from prejudgment and was able to {289} control his theories by what he found, never allowing them to warp his powers of observation. Bernard is without doubt the greatest example of the century that a fully rounded youthful training is much more favorable to successful investigation than the early specialization which is falsely supposed to foster it.

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PASTEUR, FATHER OF PREVENTIVE MEDICINE

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More than two hundred and fifty years ago, Descartes, the most original mind of the modern age, who, more than any other thinker, has determined the course both of speculative and of scientific inquiry, declared that if any great improvement in the condition of mankind was to be brought about, medicine would provide the means, and what he foresaw we see.

--Bishop Spalding.

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PASTEUR, FATHER OF PREVENTIVE MEDICINE.

Louis Pasteur is the most striking figure in nineteenth century science. In biology, in chemistry, in physics, in medicine and surgery, and in the important practical subjects of fermentation, spontaneous generation and sanitation, he has left landmarks that represent great advances in science and starting-points for new explorations into the as yet unmapped domain of scientific knowledge.

His was a typically scientific mind. His intuitions were marvellous in their prophetic accuracy, yet were surpa.s.sed by his wonderful faculty for evolving methods of experimental demonstrations of his theories.

His work has changed the whole aspect of biology and medicine, and especially the precious branches of it that refer to the cure and treatment of disease.

To such a man our generation owes a fitting monument. It has been given him. He was modest in life with the sincere modesty of the true man of science, who knows in the midst of great discoveries that he is only on the edge of truth, who realizes that "abyss calls to abyss" in the world of knowledge that lies beyond his grasp. Pasteur"s monument, very appropriately for a man of his practical bent, is no idle ornamental memorial. It is a great inst.i.tution for the perpetual prosecution of his favorite studies and for the care of patients suffering from the diseases to whose investigation the best part of his life was devoted.

In this Inst.i.tut Pasteur repose his ashes. They find a suitable resting-place in a beautiful chapel. Situate just below the main entrance a little lower than the ground floor, {294} of the inst.i.tute proper, this chapel seems to form the main part of the foundation of the building. It is symbolic of the life of the man in whose honor it was erected. He who said, "The more I know the more nearly does my faith approach that of the Breton peasant. Could I but know it all my faith would doubtless equal even that of the Breton peasant woman." On a firm foundation of imperturbable faith this greatest scientific genius of the century raised up an edifice of acquisitions to science such as it had never before been given to man to make.

Above the entrance of this chapel-tomb, and immediately beneath the words "Here lies Pasteur," is very fittingly placed his famous confession of faith:

"Happy the man who bears within him a divinity, an ideal of beauty and obeys it; an ideal of art, an ideal of science, an ideal of country, an ideal of the virtues of the Gospel." [Footnote 12]

[Footnote 12: Heureux celui qui porte en soi un dieu, un ideal de beaute et qui lui obeit; ideal de l"art, ideal de la science, ideal de la patrie, ideal des vertus de l"Evangile.]

When we turn to the panegyric of Littre in which the words occur we find two further sentences worth noting here: "These are the living springs of great thoughts and great actions. Everything grows clear in the reflections from the infinite." [Footnote 13]

[Footnote 13: Ce sont les sources vives des grandes pensees et des grandes actions. Toutes s"eclairent des reflets de l"infini.]

These words are all the more striking from the circ.u.mstances in which they were uttered. When a vacant chair (_fauteuil_) in the French academy is filled by the election of a new member of the Forty Immortals, the incoming academician must give the panegyric of his predecessor in the same chair. Pasteur was elected to the fauteuil that had been occupied by Littre. Littre, who by forty years of unceasing toil made a greater dictionary of the French language than {295} the Academy has made in the nearly two hundred years devoted to the task, was the greatest living positivist of his day. He and Pasteur had been on terms of the greatest intimacy. Pasteur"s appreciation of his dead friend is at once sincere and hearty, but also just and impartial. Littre had been a model of the human virtues.

Suffering had touched him deeply and found him ever ready with compa.s.sionate response. His fellow-man had been the subject of his deepest thoughts, though his relationship to other men appealed to him only because of the bonds of human brotherhood. Pasteur called him a "laic" saint. For many of us it is a source of genuine consolation and seems a compensation for the human virtues exercised during a long life that the great positivist died the happy death of a Christian confident in the future life and its rewards.

But Pasteur himself rises above the merely positive. The spiritual side of things appeals to him and other-worldliness steps in to strengthen the merely human motives that meant so much for Littre.

Higher motives dominate the life and actions of Pasteur himself. In the midst of his panegyric of the great positivist the greatest scientist of his age makes his confession of faith in the things that are above and beyond the domain of the senses--his ideals and his G.o.d.

There is said to exist a constant, unappeasable warfare between science and religion. Perhaps it does exist, but surely only in the narrow minds of the lesser lights. In no century has science developed as in the one that has just closed. Faraday the great scientific mind of the beginning of the century, said, at one of his lectures before the Royal Academy of Sciences of England, when the century was scarcely a decade old: "I do not name G.o.d here because I am lecturing on experimental science. But the notion of respect for G.o.d comes to my mind by ways as sure as those {296} which lead us to physical truth."

At the end of the century the monument of a great man of science is a chapel with an altar on which the sacrifice of Him that died for men is commemorated on Pasteur anniversaries.

The walls of the chapel are inscribed with the scientific triumphs of the master whose ashes repose here. It is a striking catalogue. Each heading represents a great step forward in science:

1848, Molecular Dissymmetry.

1857, Fermentations.

1862, So-called Spontaneous Generation.

1863, Studies in Wine.

1865, Diseases of Silk Worms.

1871, Studies in Beer.

1877, Virulent Microbic Diseases.

1880, Vaccinating Viruses.

1885, Prophylaxis of Rabies.

Apparently these various subjects are widely separated from one another. It might seem that Pasteur was an erratic genius. As a matter of fact, each successive subject follows its predecessor by a rigid logic. Pasteur"s life-work can be best studied by a consideration of these various topics and an appreciation of the advance made in each one.

Pasteur was first of all and always a chemist! He was interested in chemistry from his early years. In the decade from 1840 to 1850 organic chemistry--or as we prefer to call it now, the chemistry of the carbon compounds--was just opening up. Great discoveries were possible as they were not before or since. Pasteur, with a devotion to experimental work that amounted to a pa.s.sion, was a pupil at the Ecole Normale, in Paris. Bruited about he heard all the suggestive questions that were insoluble problems even to the great men around him. He was especially interested in the burning {297} question of the day, the internal const.i.tution of molecules and the arrangement of atoms in substances which, though they are composed of exactly the same const.i.tuents, exhibit very different physical and chemical qualities.

The subject is, almost needless to say, a basic problem in chemistry and remains to our own day the most attractive of scientific mysteries.

Mitscherlich, one of the greatest chemists of the time, had just announced that certain salts--the tartrates and paratartrates of soda and ammonia--"had the same chemical composition, the same crystalline form, the same angles in the crystalline condition, the same specific weight, the same double refraction and, consequently, the same inclination of the optic axes. Notwithstanding all these points of similarity, if the tartrate is dissolved in water it causes the plane of polarized light to rotate while the paratartrate exerts no such action." Pasteur could not believe that all the chemical and physical qualities of two substances could be identical and their action to polarized light be so different. Mitscherlich was known, however, as an extremely careful observer. For several years Pasteur revolved all the possibilities in Mitscherlich"s observations and, finally, came to the conclusion that there perhaps existed in the paratartrates, as prepared by Mitscherlich, two different groups of crystals, the members of one of which turned the plane of polarization to the right, the other to the left. These two effects neutralized each other and apparently the paratartrates have no influence on the polarized beam of light.

Pasteur found that the paratartrates were composed of crystals that were dissymmetrical--that is, whose image reflected in a mirror cannot be superposed on the crystal itself. This idea Pasteur makes clear by reference to the mirrored image of a hand. The image of the right hand as {298} seen in a mirror is a left hand. It cannot be superposed on the hand of which it is the reflection any more than the left hand can be superposed on the right and have corresponding parts occupy corresponding places. Pasteur found that the paratartrates were not only dissymmetrical, but that they possessed two forms of dissymmetry.

The mirrored image of some of the crystals could be superposed on certain of the other crystals just as the mirror image of the right hand can be superposed on the actual left hand. He concluded that if he separated these two groups from each other he would have two very different substances, and so the mystery propounded by Mitscherlich would be solved.

With Pasteur to conceive an idea was to think out its experimental demonstration. He manufactured the paratartrates according to the directions given by Mitscherlich, and then proceeded to sort the two varieties of crystals by hand. It was slow, patient work, and for hours Pasteur strove feverishly on alone in the laboratory. At length, the crystals were ready for solution and examination as to their effect upon polarized light. If Pasteur"s idea as to the dissymmetry of crystals were confirmed, a great scientific advance was a.s.sured.

Tremblingly the young enthusiast adjusted his polariscope. He tells the story himself of his first hesitant glance. But hesitation was changed to triumph. His prevision was correct. There were two forms of crystals with different effects on polarized light in Mitscherlich"s supposed simple substance. Pasteur could not stay to put his instrument away. The air of the laboratory had become oppressive to him. Drunk with the wine of discovery, as a French biographer remarks, he rushed into the open air and almost staggered into the arms of a friend who was pa.s.sing. "Ah," he said, "I have just made a great discovery. Come to the Luxembourg garden and I will tell you all about {299} it." It was characteristic of the man all through life to have no doubt of the true significance of his work. He was sure of each step in the demonstration and his conclusions were beyond doubt.

Pasteur"s discovery made a profound sensation. The French Academy of Sciences at once proceeded to its investigation. Among the members who were intensely interested, some bore names that now belong to universal science--Arago, Biot, Dumas, De Senarmont. Pasteur told long years afterward of Biot"s emotion when the facts were visibly demonstrated to him. Greatly moved, the distinguished old man took the young man"s arm and, trembling, said: "My dear child, I have loved science so well that this makes my heart beat." How deeply these men were bound up in their work! How richly they were rewarded for their devotion to science! There were giants in those days.

Pasteur"s discovery was much more than a new fact in chemistry and physics. It was the foundation-stone that was to support the new science of stereochemistry--the study of the physiochemical arrangement of atoms within the molecule--that took its rise a few years later. Much more, it was a great landmark in biology. Pasteur pointed out that all mineral substances--that is, all the natural products not due to living energy--have a superposable image and are, therefore, not dissymmetrical. All the products of vegetable and animal life are dissymmetrical. All these latter substances turn the plane of polarization. This is the great fundamental distinction between organic and inorganic substances--the only one that has endured thus far in the advance of science. Dissymmetry probably represents some essential manifestation of vital force. Often there seem to be exceptions to this law; but careful a.n.a.lysis of the conditions of the problem shows that they are not real.

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An apparent contradiction, for instance, to this law of demarcation between artificial products and the results of animal and vegetable life is presented by the existence in living creatures of substances like oxalic acid, formic acid, urea, uric acid, creatine, creatinin, and the like. None of these substances, however, has any effect on polarized light or shows any dissymmetry in the form of its crystals.

These substances, it must be remembered, are the result of secondary action. Their formation is evidently governed by the laws which determine the composition of the artificial products of our laboratory, or of the mineral kingdom properly so called. In living beings they are the results of excretion rather than substances essential to life. The essential fundamental components of vegetables and animals are always found to possess the power of acting on polarized light. Such substances as cellulose, fecula, alb.u.min, fibrin, and the like, never fail to have this power. This is sufficient to establish their internal dissymmetry, even when, through the absence of characteristic crystallization, they fail to manifest this dissymmetry outwardly.

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