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 surpassed 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 institution 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 Institut 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 institute
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 circumstances 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
compassionate 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 God.
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 God here because I am lecturing
on experimental science. But the notion of respect for God 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 passion, 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 constitution of molecules and the arrangement of atoms in
substances which, though they are composed of exactly the same
constituents, 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 assured.
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 passing. "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 analysis of the
conditions of the problem shows that they are not real.
{300}
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, albumin,
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.
It would scarcely be possible to indicate a more profound distinction
between the respective products of living and of mineral nature than
the existence of the dissymmetry among living beings and its absence
in all merely dead matter. It is strange that not one of the thousands
of artificial products of the laboratory, the number of which is each
day growing greater and greater, should manifest either the power of
turning the plane of polarization or non-superposable dissymmetry.
Natural dissymmetrical substances--gum, sugar, tartaric and malic
acids, quinine, strychnine, essence of turpentine, and the like--may
be and are employed in forming new compounds which remain
dissymmetrical though they are artificially prepared. It is evident,
however, that all these new {301} products only inherit the original
dissymmetry of the substances from which they are derived. When
chemical action becomes more profound--that is, becomes absolutely
analytic or loosening of the original bonds imposed by nature--all
dissymmetry disappears. It never afterward reappears in any of these
successive ulterior products.
"What can be the causes of so great a difference?" We quote from
Pasteur's life by his son-in-law: "Pasteur often expressed to me the
conviction," says M. Radot, "that it must be attributed to the
circumstance that the molecular forces which operate in the mineral
kingdom and which are brought into play every day in our laboratory
are forces of the symmetrical order; while the forces which are
present and active at the moment when the grain sprouts, when the egg
develops, and when under the influence of the sun the green matter of
the leaves decomposes the carbonic acid of the air and utilizes in
diverse ways the carbon of this acid, the hydrogen of the water and
the oxygen of these two products are of the dissymmetrical order,
probably depending on some of the grand dissymmetrical cosmic
phenomena of our universe."
For the first few years after this discovery Pasteur endeavored by
every possible means to secure experimental modifications of some of
these phenomena of dissymmetry. He hoped thus to learn more fully
their true nature. Magnetic influences especially would, he hoped,
enable him to pierce, at least to some degree, this fundamental
mystery of nature. While acting as professor at Strasburg, he procured
powerful magnets with the view of comparing the actions of their poles
and, if possible, of introducing by their aid among the forms of
crystals a manifestation of dissymmetry. At Lille, where he was for
several years dean of the scientific faculty, he contrived a piece of
clockwork intended {302} to keep a plant in continual rotary motion,
first in one direction and then in the other. "All this was crude," he
says himself, "but further than this I had proposed with the view of
influencing the vegetation of certain plants to invert, by means of a
heliostat and a reflecting mirror, the motion of the solar rays which
should strike them from the birth of their earliest shoots. In this
direction there was more to be hoped for."
He did not have time, however, to follow out these ingenious
experiments. He became involved, as we shall see, in labors more than
sufficient to take up all his time and all his energy. These labors
were of great practical importance for France. Pasteur always
insisted, however, that great discoveries will yet be made in
following out this order of ideas, and that there is in this subject
magnificent opportunity for young men possessed of the genius of
discovery and the power of persistent work.
When, only a few years ago, Professor Duclaux, Pasteur's successor as
the head of the Pasteur Institute, and himself one of the greatest
living authorities on biological chemistry, wrote the story of the
mind of the master, [Footnote 14] he said, of this subject of
dissymmetry: "A living cell appears to us, then, as a laboratory of
dissymmetrical forces, a bit of dissymmetrical protoplasm acting under
the influence of the sun--that is to say, under the influence of
exterior dissymmetrical forces. It presides over actions of very
different kinds. It can manufacture, in its turn, new dissymmetrical
substances which add to or take away from its energy. It can, for
instance, utilize one of the elements of a paratartrate without
touching another. It can manufacture crystalline sugar at one moment
and consume it at another, laying by stores for itself to-day using
them up to-morrow. In a word, the living cell {303} presents a
marvellous plasticity, which exerts itself without the slightest
disturbance by minimal deviations of forces due to dissymmetrical
influence. Ah, if spontaneous generation were only possible! If we
could only create living matter, raise up in the midst of inactive
mineral material a living cell, then it would be easy for us to
understand something more of vital manifestations and to comprehend
better the mystery of dissymmetry."
[Footnote 14: L'Histoire d'un esprit, par M. Duclaux, Paris, 1896.]
But spontaneous generation is as far off as ever. Pasteur's
discoveries in dissymmetry have brought us closer than ever before to
the mystery of life. Scientists still hope, but it is with ever-waning
confidence, that they may pluck out the heart of the mystery.
Pasteur's own thoughts with regard to dissymmetry rose above even the
lofty heights of mere earthly biology. He saw in it the great force
that links the universe together. On one occasion, at the Academy of
Sciences, he expressed himself as follows:
"The universe is a dissymmetrical whole. I am inclined to think that
life, as manifested to us, must be a function of the dissymmetry of
the universe or of the consequences that follow in its train. The
universe is dissymmetrical; for, placing before a mirror the group
of bodies which compose the solar system with their proper movement,
we obtain in the mirror an image not superposable on the reality.
Even the motion of solar light is dissymmetrical. A luminous ray
never strikes in a straight line. Terrestrial magnetism, the
opposition which exists between the north and the south poles of a
magnet, the opposition presented to us by positive and negative
electricity, are all the resultants of dissymmetrical actions and
motions."
This raising of his thoughts far above the sordid realities he is
concerned with into the realms of suggestive theory is typical of
Pasteur. His was a true creative mind--poetic {304} in its highest
sense. The imagination properly controlled is of as great value to the
scientist as to the poet. Pasteur's theories were ever pregnant with
truth to be. All his life he kept this question of dissymmetry before
his mind and hoped to get back to work at it. But opportunity failed.
Other and more practical work was destined to occupy the busy
half-century of investigation that followed.
Most of Pasteur's work, after this first thrilling discovery and its
possible significance, is very well known. His meditations on the
distinction between material derived from living and non-living
sources led him to investigate certain processes called
fermentations--before his time considered merely chemical. It is well
known that if a dilute solution of sugar be exposed to the air
anywhere in the world it will ferment--that is, certain changes will
take place in the liquid, some gas will escape from its surface and
alcohol will be formed. There are changes that take place in other
organic substances--milk, meat solutions, butter, etc.--that resemble
quite closely alcoholic fermentations, though the end-product of the
process is not alcohol. Pasteur showed that all these supposed
chemical changes are really due to the presence of minute living
cells, called ferments. During the growth of these cells they split up
the substances contained in the material in which they occur, using
parts of them for their nutrition. He proved this very clearly for the
lactic acid and butyric acid fermentations. Milk was supposed to
become sour and butter rancid because they are unstable organic
compounds, liable to change in the presence of the oxygen of the air.
These changes were now shown to be due to minute living things that
grow in the milk and the butter.
When Pasteur offered the same explanation of the origin of vinegar he
found a strenuous opponent in Liebig, the great chemist. Liebig
admitted the existence of specific substances, {305} called ferments,
but said that they were nitrogenous compounds in unstable equilibrium
as regards their composition, and with a marked tendency to undergo
alteration when exposed to the air or free oxygen. These alterations,
once begun, affect also the liquids in which the ferments are
contained--milk, blood, sugar solutions and the like. Theodore Schwann
had shown the existence of certain yeast-like bodies in fermenting
liquids, but these were considered to be effects, not causes, of the
fermentation, and even Schwann, himself, believed that they originated
in the liquids in which they were found. It remained for Pasteur to
demonstrate, as he did by a brilliant series of ingenious and
conclusive experiments, that ferments are living cells, that they
never originate except from previous cells of the same species, and
that no fermentation takes place unless they are present.
The changes that take place in organic liquids when exposed to the air
and the frequent development in such liquids of moving bodies
evidently possessed of life constituted, before Pasteur's time, the
principal reason for believing that life might originate from some
special combination of chemical forces, and without the necessity for
preceding life of the same species as its efficient cause. The new
explanation of fermentation greatly weakened the position of those who
believed in spontaneous generation--that is, the origin of life from
dead matter under certain specially favorable circumstances. Pasteur
proceeded to show, by rigid demonstration, that if all life were
destroyed in organic substances, living beings never originated in
them unless living seeds from the air gained access to them. After a
meat solution has been thoroughly boiled nothing living develops in
it, even though the air is allowed free access, if the air admitted
has been previously filtered through cotton, He showed that even the
{306} bending of the neck of the tube into the shape of an "S," so as
to prevent the entrance of dust particles, suffices to protect the
most changeable organic material from the growth of micro-organisms in
it. His teaching was not accepted at once. Details of his experiments
were impugned. Apparently complete counter-demonstrations were made,
but Pasteur knew how, by his marvellous intuition, to detect the
fallacy of supposed demonstration, and to invent new crucial tests of
the proof of biological succession.
These studies in minute life and in fermentation led him almost
naturally to the study of disease. Two centuries before, Robert Boyle,
of whom his notorious descendant the great bullster, Sir Boyle Roche,
had said that he was the father of chemistry and the brother of the
Earl of Cork, made use of an expression wonderfully prophetic in its
accurate penetration of the future. "He that thoroughly understands
the nature of ferments and fermentations," said Boyle, "shall probably
be much better able than he that ignores them to give a fair account
of divers phenomena of certain diseases (as well fevers as others)
which will perhaps be never properly understood without an insight
into the doctrine of fermentations." The marvel is that the very first
man who understood the nature of fermentation proved to be the one
destined to unlock the mystery of contagious disease and its origin.
Pasteur's first investigations in the field of disease concerned a
mysterious malady that affected the silkworm and was ruining the silk
industry of France. This disease was first noted seriously about 1850.
When a colony of silkworms had been attacked it was useless to try to
do anything with them. The only resource for the silk farmers was to
get the eggs of an unaffected race of worms from some distant country.
These became infected after several generations, {307} and untainted
eggs had to be brought from a distance once more. Soon the silkworm
plague invaded most of the silk-growing countries of Europe. In 1864,
only the races of silkworms in China and Japan were surely not
infected. Great suffering had been entailed on many departments of
France by the failure of the silk industry. The most careful
investigation failed to reveal any method of combating the disease.
Acute observers had been at work and some very suggestive observations
on the affected worms had been made, but the solution of the problem
of the prevention of the disease seemed as far off as ever. In 1863
the French minister of agriculture formally agreed to pay 500,000
francs (about $100,000) to an Italian investigator who claimed to have
found a remedy for the disease, if his remedy proved efficient. The
offer was to no purpose. In 1865 the weight of cocoons of silk had
fallen to 4,000,000 kilos. It had formerly been nearly 30,000,000
kilos. This involved a yearly loss of 100,000,000 francs (about
$20,000,000).
Pasteur showed that the failure of the silkworm was not due to one
disease, but to two diseases--pebrine and flacherie. These diseases
are communicated to the eggs of the worms, so that the young begin
life handicapped by the maladies. The crawling of the worms over
leaves and stems makes these liable to communicate the diseases. The
prevention of the diseases is accomplished by procuring absolutely
healthy eggs and then never letting them come in contact with anything
that may have been touched by diseased worms. If, at the egg-laying
period, worms show any signs of disease their eggs are to be rejected.
These simple suggestions were the result of rigid experimental
demonstration of the spread of the diseases from worm to worm,
including the demonstration of the microbic causes of the two
diseases. These precautions proved effective, {308} but their
introduction met with opposition. The strain of the work and the worry
of controversy brought Pasteur to the brink of the grave by a
paralytic stroke. From this he never entirely recovered and was always
afterward somewhat lame. After the severest symptoms had passed off he
was given the opportunity to make a crucial test of preventing the
silkworm diseases at the villa of the French Prince Imperial. The
products obtained from the silkworms on the estate had, for years, not
sufficed to pay for the fresh supplies of eggs obtained from a
distance. Pasteur was given full charge of the silk industry on the
estate. The sale of the cocoons at the end of the year gave a net
profit of 26,000,000 francs (over $5,000,000). This decisive
demonstration effectually ended all opposition.
His attention was next naturally directed to the diseases of animals
and human beings. His studies in fermentations and in silkworm
diseases had taught him the use of the microscope for such
investigations. Splenic fever--known also as anthrax--a disease that
attacks most species of domestic animals and may also prove fatal to
man, was the first to yield the secret of its origin. The cause proved
to be a bacterium--that is, a small, rod-shaped plant. This was but
the first of a series of similar discoveries, until now the science of
bacteriology has become one of the most important branches of
knowledge. Pasteur's investigations included much more, however, than
the mere discovery of the germ of the disease. He showed that a series
of diseases which passed under different names in different animals
were all due to the same cause. Further, he discovered one of the
methods of distributing the disease. When the carcasses of animals
that have died from the disease are not buried deeply below the
surface of the ground, animals grazing above may become infected with
the disease. {309} The germs of the disease can be shown to occur in
the grass above the graves. It is carried to the surface in the bodies
of earth-worms. This important observation was the first hint of the
methods of disease distribution by some living intermediary. Modern
medicine has come to understand that these biological distributing
agents are far more important than the fabled transmission through the
air.
Pasteur overturned the notion of spontaneous generation of life. Then
his work eradicated the idea of the spontaneous generation of disease.
It opened up a new era by showing that the origin of many diseases is
not due to changes in the atmosphere nor to some morbid productivity
of soil or water under favoring circumstances, but to minute living
organisms whose multiplication is encouraged by the conditions that
were supposed to produce disease. Finally, came the precious
suggestion that living things always convey and distribute disease;
man to man, for epidemics travel not with the velocity of the wind but
only as fast as the means of communication between distant points;
animal to man, as is well known, for many diseases now; and, lastly,
insects, worms and the like were also shown to be real carriers of
disease.
In investigating chicken cholera Pasteur discovered another great
basic principle in the knowledge of disease, especially of its
treatment. After considerable difficulty he succeeded in finding the
germ of this disease which was causing great losses in the poultry
industry of France and other European countries. This germ was
cultivated for a number of generations on artificial media and never
failed to produce the disease when fowls had been inoculated. During
the course of his studies in the malady Pasteur was called away to a
distant part of France in connection with his investigation of
anthrax. He was away from his laboratory for several months. When he
returned he inoculated {310} some fowls with the cultures of chicken
cholera which he had left behind. To his surprise and annoyance the
inoculations failed to produce the typical symptoms of the disease.
The fowls suffered from some slight symptoms and then recovered. When
he left his laboratory inoculations had been invariably fatal. It took
considerable time and trouble to procure fresh cultures of the
chicken-cholera microbe. Meantime, the fowls which had been only
slightly affected by the old cultures were carefully preserved. When
these birds were inoculated with the fresh virulent cultures they
failed to take the disease. Other fowls promptly died, exhibiting all
the characteristic symptoms of chicken cholera. Those that had
suffered from the mild form of the disease produced by the old
cultures were protected from further attacks of the disease.
One of the great mysteries of medicine, the varying virulence of
disease, had been thus solved by what seemed an accident. There are no
accidents in the lives of great investigators. There are surprises,
but genius knows how to reconcile their occurrence with the principles
they are working out. Pasteur understood at once the wonderful utility
there might be in this discovery for the protection of men and animals
from disease. He proceeded to practical applications of the new theory
by providing old cultures for the inoculation of fowls in districts
where chicken cholera produced serious ravages. Then, working on the
same lines as for chicken cholera, he proceeded to elaborate vaccine
material for anthrax.
Vaccine was the name deliberately selected for the inoculating
substance in order to honor the genius of the English physician
Jenner, who had discovered the power of vaccination to protect from
smallpox. The weakening of the germs of anthrax, so as to produce only
a mild form of the disease, was a much more intricate problem than for
chicken cholera, {311} because the anthrax bacillus does not weaken
with age, but enters a resting or spore stage, resembling the seed
stage in large plants. After a patient series of investigations
Pasteur accomplished his object by some ingenious methods that served
to show, perhaps better than any other details of his career, how
thoroughly practical was his inventive genius.
Unfortunately the absorption in his work proved too much for his
health. He was seized by a series of apoplectic attacks which for a
time threatened to put an end to his invaluable career. When he did
begin to recover his health one of the most serious problems in his
regard was to keep him from hindering his convalescence by a return to
his old-time absorption in the important problems of the cure and the
prevention of disease, at which he had been so happily engaged. The
keynote of Pasteur's life was to prevent human suffering as far as
possible, and any time not given to this important duty seemed to him
to be utterly wasted. With regard to this unfortunate break in
Pasteur's work Dr. Christian Herter, in his address on the "Influence
of Pasteur in Medical Science," delivered before the Medical Society
of Johns Hopkins University, [Footnote 15] has an interesting passage,
in which he discusses the significance of the master's work up to this
time, and the interest that his illness awakened among all the
distinguished medical scientists of Europe at the time:
[Footnote 15: New York: Dodd, Mead & Co., 1904.]
"It is likely that excessive work and mental stress in some degree
contributed to the onset of the series of paralytic seizures which
in October, 1868, threatened the life of Louis Pasteur. During the
critical period of his illness, many of the most distinguished
scientific men of France vied with each other to share with Mme.
Pasteur the privilege of nursing the man they loved so well and of
rescuing the life {312} that had already placed science and a nation
under enduring obligation through discoveries which were either of
the greatest practical utility or appeared susceptible of almost
unlimited development. Had Pasteur died in 1868, he would have left
a name immortal in the annals of science. Others would in some
degree have developed his ideas. Already inspired by the researches
on fermentation, Lister would have continued to develop those
life-saving surgical methods which will forever be associated with
his name. But we may well question whether investigations in biology
and medicine would not have been for a time at least conducted along
less fruitful paths. Who shall say how soon the great principle of
experimental immunity to pathogenic bacteria, the central jewel in
the diadem of Pasteur's achievements, would have been brought to
light?"
When Pasteur recovered sufficiently to resume work, it was soon clear
to apprehensive friends that he had no intention of leaving his ideas
to be worked out by other men. The miseries of the Franco-Prussian War
deeply affected him, and could not fail to inhibit his productiveness,
but after a time the unquenchable love for experimental research was
once more ascendant and there began a new epoch, the epoch of great
discoveries relating to the origin and cure or prevention of the
infectious diseases of man and the domestic animals. As in the case of
Ignatius Loyola, it seems as if the lamp of the genius shone with a
larger and more luminous flame after the onset of bodily infirmity in
defiance of the physical mechanism which is too often permitted to
master the will.
After his illness Pasteur devoted himself even more than before to the
study of the various biological problems connected with human
diseases. There was one exception to this, in his series of studies on
beer, undertaken shortly after {313} the Franco-Prussian War. Pasteur
was an ardent patriot, so much so, indeed, that after the war he sent
back to the German government certain decorations and diplomas that
had been conferred upon him. He thought that his country had been
overreached by a scheming, political statesman, bent on the
aggrandizement of the kingdom of Prussia. To the end of his life this
feeling of hostility never entirely vanished. It was his hope, then,
that by improving the character of French beer it might not only be
made more wholesome in the best sense of the word, but also that the
French brewing industry might be made a serious rival of its German
competitors. Pasteur's discoveries are the most important for the
brewing industry that have ever been made. The Germans proved,
however, even more capable of taking advantage of them than his French
compatriots.
After this Pasteur devoted himself without further interruption to the
study of the microbic diseases of man. His greatest practical triumph
was undoubtedly with regard to hydrophobia, or, as it is more properly
called, rabies. The mystery of the disease was most illusive. Pasteur
could not succeed in finding the germ of the disease. Even down to our
own day it has not been satisfactorily demonstrated. In spite of this
lack of an important element of knowledge, which might be supposed
absolutely essential for the successful therapeutics of rabies from a
biological standpoint, Pasteur succeeded in producing material that
would protect those bitten by rabid dogs from developing the affection.
Long and bitter was the opposition to the introduction of his method
of treatment. The greatest living German bacteriologist said that it
was idle to provide "remedies of which we know nothing for diseases of
which we know less." The reference was to the failure to find the germ
of the disease and the claim, nevertheless, of having discovered {314}
a cure. Wherever the Pasteur treatment for rabies was introduced,
however, the number of deaths following the bites of mad animals fell
off. In Russia, where the mad wolves of the Steppes so often inflict
fatal bites, the power of the new treatment was soon recognized. In
Hungary its value was appreciated without delay. Then the British
government, after a most careful investigation, introduced it into the
Indian army. Then Austria took it up officially. At the International
Medical Congress at Moscow, in 1897, Americans, who expressed doubts
as to the efficiency of the Pasteur treatment for rabies, were laughed
at by the medical representatives of nations who have the most
opportunities for studying the disease. Shortly after the Moscow
congress the German government officially announced its intention of
treating all persons bitten by rabid animals by the Pasteur method. A
Pasteur institute for the treatment was opened in connection with the
University of Berlin. With this the last serious opposition
disappeared. The Germans are now enthusiastic advocates of the value
of the Pasteur treatment. The statistics of the Berlin Pasteur
Institute are pointed to as demonstrating beyond doubt the possession
of power to cope with one of the most fatal diseases man is liable to.
Alas, that this should not have come during the master's lifetime! It
would have been the happiest moment of Pasteur's life to have had his
ideas triumphant in Germany. Unlike the generality of great men,
however, Pasteur enjoyed the meed of almost unstinted appreciation
during life.
Geniuses are often said to be neglected by their contemporaries. The
expression is exemplified much less frequently in our own time than
formerly. The rapid diffusion of ideas, and the consequent control and
confirmation of scientific claims by many minds, enable the present
generation to recognize merit before its possessor has starved. {315}
Pasteur's career was certainly an exemplification of the fact that
true genius, though it may meet with opposition, will be well
rewarded. The son of the poor tanner of Dole, by the mere force of his
intellectual energy, lifted himself to the level of earth's great
ones. His funeral obsequies were a pageant in which French officialdom
felt itself honored to take part. The President of the French
Republic, the members of both houses of the legislative department,
the officials of the city of Paris, the members of the faculty of the
university, of the French Academy, and of the various scientific
societies of the French capital, gathered to honor their mighty dead.
Never has it been given to anyone without family prestige or political
or ecclesiastical influence to have a great world-capital and a great
nation accord such glorious obsequies, while all the world extended
its sympathy and added paeans of praise.
Nor was it only at the moment of death that the expression of sincere
respect and merited honor was paid. When there was question of
erecting a Pasteur institute, in which the master's great work could
be carried on more effectually, contributions poured in from every
part of France and from all over the civilized world. Two of the
world's greatest hereditary rulers made it a point to visit the humble
laboratory of the great scientist whenever they came to Paris.
Alexander II, the Czar of the Russians, was the intimate friend of the
tanner's son, who became the world's benefactor. Dom Pedro II, the
late Emperor of Brazil was another royal visitor to Pasteur. In the
library of the _Institut Pasteur_ at Paris, the busts of these two and
of two other great friends of his, scarcely less in worldly importance
and greater in their beneficence, keep watch above the ashes of the
dead scientist. They are Baroness Hirsch, the world benefactress, and
Baron Albert Rothschild, the head of the French branch of the great
banking family.
{316}
All united in honoring the marvellous genius whose work has proved of
such practical utility for mankind, and whose discoveries are as yet
only beginning their career of pregnant suggestiveness to scientific
men. His genius has brought the great ones of earth to his level or
raised him to theirs. His own thought on the equality of man is a
confession of the faith that was in him. It was expressed in his
discourse of reception into the French Academy in the midst of the
panegyric on Littre, from which we quoted at the beginning of this
sketch: "Where are the true sources of human dignity, of liberty and
of modern democracy, if not in the infinite, before which all men are
equal? The notion of the infinite finds everywhere its inevitable
expression. By it the supernatural is at the bottom of every heart."
Pasteur, the man, is, however, if possible, even more interesting than
Pasteur, the greatest of living scientists. In the midst of all his
work and his wonderful success, amid the plaudits of the world,
Pasteur remained one of the simplest of men and the kindest of friends
to those who knew him. Dr. Roux's expression is well known: "The work
of Pasteur is admirable; it shows his genius; but one must have lived
on terms of intimacy with him in order to know all the goodness of his
heart." He was kindness personified, and those who think of him as a
cruel vivisector and encourager of experiments upon animals that cause
suffering, belie him and his humanity very much. He would never permit
animals to be used in experiments without an anesthetic, and even then
only when he deemed that use absolutely necessary for the furtherance
of projects that promised great benefit to humanity. Nothing was
harder for him to do than to walk the hospitals and see human
suffering when he was studying the causes of disease in human beings.
Even the slight pain inflicted during the {317} injections for
hydrophobia was a source of great discomfort to him, and his anxiety
with regard to these patients was one of the main causes of the
breakdown in health that shortened his life.
One of the most beautiful things about Pasteur's personal life is the
relation to his family, and especially to his children, and their
union in religious simplicity. On the occasion of the death of his
father, whom Pasteur loved very deeply and for whom he had instilled
the deepest affection into the hearts of his children, he wrote to his
daughter, whose first communion was to occur on that day. His letter
is that of a man deeply affectionate, sincerely religious, and
eminently trustful of the future that faith alone points out. His
letter runs:
"He died, my dear Cecelia, the day of your first communion. Those
are two memories which will, I hope, never leave your heart, my dear
child. I had a presentiment of his death when I asked you to pray
particularly on that morning for your grandfather at Arbois. Your
prayers will surely be very agreeable to God at such a time, and who
knows if grandpa himself did not know of them and did not rejoice with
our little Jeanne [a daughter who had died the year before] over the
pious sentiments of Cecelia?"
It is not surprising, then, to find many other expressions of
Pasteur's extreme interest in spiritual things, though they might have
been little expected from a man so deeply immersed in scientific
investigations as he was. After all, it must not be forgotten that his
discoveries, by solving the mystery that surrounds the origin of
disease, cleared some of the ways of Providence of that inscrutable
character which is supposed in shallow minds to constitute the
greatest part of their impressiveness. With epidemics explained, not
as dispensations of Divine Providence, but as representing the
sanction of nature for the violation of natural laws, one of the {318}
reasons for which mankind worshipped the Deity seemed to be gone. The
man who had done most to make clear these mysterious processes of
nature was, however, himself far from thinking that materialism offers
any adequate explanation of the mysteries of life, or of the relations
of man to man, and of man to his Creator. Impatient at the pretensions
of such pseudoscientists, Pasteur once said: "Posterity will one day
laugh at the sublime foolishness of the modern materialistic
philosophy. The more I study nature, the more I stand amazed at the
work of the Creator. I pray while I am engaged at my work in the
laboratory."
For Pasteur, death had no mysteries. He had written to his father,
once, on the death of his little daughter Jeanne: "I can only think at
this moment of my poor little one so good, so full of life, so happy
in living, and whom this fatal year, now drawing to a close, has
snatched from us. After a very short time she would have been for her
mother and for me, for all of us, a friend, a companion, a helpmate.
But I ask your pardon, dear father, for recalling to you such sad
memories. She is happy. Let us think of those who remain, and let us
try to prevent for them, as far as lies in our power, the bitternesses
of life." So, when it came to the hour of his own death, Pasteur faced
it with the simple confidence of a sincere Christian, and the
undoubting faith of a lifelong son of the Church. For many hours he
remained motionless, one of his hands resting in that of Madame
Pasteur, while the other held a crucifix. His last conscious glance
was for his lifelong companion, his last conscious act a pressure of
the image of his Redeemer. Thus, surrounded by his family and
disciples in a room of almost monastic simplicity, on Saturday,
September 28, 1895, about five in the afternoon, passed peacefully
away the greatest of the nineteenth century scientists.
{319}
Almost needless to say, the life of a man like Pasteur contains the
most wonderful lessons for the young scientists of the twentieth
century. Few men have lived their lives so unselfishly, and with so
much preoccupation for the good that they might accomplish, as he did.
To have remained in the midst of it all simple, earnest and faithful
to duty, without self-seeking, is a triumph worthy of recording, and
makes a career well deserving of emulation. When Pasteur made his
discoveries with regard to fermentation the Empress of the French
asked to be shown just what his investigations had demonstrated.
Pasteur went to Court for the purpose, and after the Emperor and
Empress had been shown the ferment cells, and expressed their
interest, Eugenie said: "Now, you will develop this discovery
industrially, will you not?" Pasteur replied. "Ah, no, that will be
left for others. It does not seem to me that it would be worthy of a
French scientist to allow himself to be diverted to the industrial
applications of his discoveries, even though it might prove eminently
lucrative for him." As a matter of fact, had Pasteur allowed himself
to be allured into the foundation of an immense manufactory
constructed and directed on the great principles which he had
discovered, there seems no doubt that this would have been a wonderful
money-making scheme. Certain it is that the capital for such an
adventure would have been readily available. Had Pasteur yielded to
the solicitations made him he might have died worth many millions,
instead of the very modest competency which came to him in the
ordinary course of his scientific labors. The money might have seemed
a temptation for the sake of his children, but the world would have
lost all the great discoveries with regard to human diseases. It is
not unlikely that these would have been made even without Pasteur,
There is no doubt, however, that their discovery {320} would have been
very much delayed and that as a consequence almost untold human
suffering that has been prevented would have occurred. It must never
be forgotten that such men as Lister and Koch derived their most
fertile suggestions from the discoveries made by Pasteur.
Pasteur's life may very well be held up, then, as a model to the
present and future generations of what the highest ideals of a
scientific career can be. Dr. Christian Herter, in the discourse
already quoted from, has stated this so well and at the same time has
joined with it so felicitously a quotation from Pasteur's advice to
young men, that we can find no better way in which to close this
consideration of Pasteur's career than by quoting him once more:
"To have fought the long battle of life with unwavering constancy to
the loftiest ideals of conduct, toiling incessantly without a
thought of selfish gain; to have remained unspoiled by success and
unembittered by opposition and adversity; to have won from nature
some of her most precious and covert secrets, turning them to use
for the mitigation of human suffering;--these are proofs of rare
qualities of heart and mind. Such full success in life did Louis
Pasteur attain, and from the consciousness of good achieved his
noble nature found full reward for all his labors.
"Of the children whom nature has endowed with splendid gifts there
are few whose lives have affected so profoundly and so beneficently
the fate of their fellows, few who have earned in equal degree the
gratitude and reverence of all civilized men. Although not many can
hope to enrich science with new principles, all of us may gain from
Pasteur's life the inspiration to cultivate the best that is in us.
Let us keep living in our memories the inspiring words which the
master spoke on the seventieth anniversary of his birthday:
"'Young men, young men, devote yourselves to those sure {321} and
powerful methods, of which we as yet know only the first secrets.
And I say to all of you, whatever may be your career, never permit
yourselves to be overcome by degrading and unfruitful skepticism.
Neither permit the hours of sadness which come upon a nation to
discourage you. Live in the serene peace of your laboratories and
your libraries. First, ask yourselves, What have I done for my
education? Then, as you advance in life, What have I done for my
country? So that some day that supreme happiness may come to you,
the consciousness of having contributed in some manner to the
progress and welfare of humanity. But, whether our efforts in life
meet with success or failure, let us be able to say, when we near
the great goal, 'I have done what I could.'"
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