served in the Spanish campaign of 1812-1813 as a private in the third
regiment of infantry, called ‘le brave parmi les braves.’ In course of
time he was promoted to be sergeant-major, and in March, 1814, received
the Cross of the Legion of Honour. Two months later the abdication had
taken place; and the regiment was at Douai, re-organizing under the name
of ‘Régiment Dauphin.’ Here was no place for Jean-Joseph, devoted to the
Imperial Eagle and unmoved by the Fleur-de-lys. He received his
discharge, and made his way across country to his father’s town,
Besançon. At Besançon he took up his father’s trade and became a tanner;
and, after one feverish flush during the Hundred Days, and one contest,
in which he came off victor, with the Royalist authorities, who would
take his sword to arm the town police, he settled down into a quiet,
law-abiding citizen, more occupied with domestic anxieties than with the
fate of empires.
Hard by the tannery ran a stream, called La Furieuse, though it rarely
justified its name. Across the stream dwelt a gardener named Roqui;
amongst the gardener’s daughters one Jeanne-Étiennette attracted the
attention of, and was attracted by, this old campaigner of twenty-five
years. The curious persistence of a family in one place, combined with
the careful preservation of parish records, enables M. Vallery-Radot to
trace the family Roqui back to the year 1555. We must content ourselves
with Jeanne-Étiennette, who in 1815 married Jean-Joseph. Shortly
afterwards the young couple moved to Dôle and set up house in the Rue
des Tanneurs.
Louis Pasteur’s father was a somewhat slow, reflective man; a little
melancholic, not communicative; a man who lived an inner life, nourished
doubtless on the memories of the part he had played on a larger stage
than a tannery affords. His mother, on the other hand, was active in
business matters, hard-working, a woman of imagination, prompt in
enthusiasm.
Before Louis Pasteur was two years old, his parents moved first to
Marnoz and then to a tannery situated at the entrance to the village of
Arbois; and it was Arbois that Pasteur regarded as his home, returning
in later life year after year for the scanty absence from his laboratory
that he annually allowed himself. Trained at the village school, he
repeated with his father every evening the task of the day. He showed
considerable talent, and his eagerness to learn was fostered by the
interest taken in him by M. Romanet, principal of the College of Arbois.
At sixteen he had exhausted the educational resources of the village;
and, after much heart-searching and anxious deliberation, it was decided
to send the young student to Paris to continue his studies at the Lycée
Saint-Louis. It was a disastrous experiment. Removed so far from all he
knew and loved, Louis suffered from an incurable home-sickness, which
affected his health. His father hearing this, came unannounced to
Paris, and with the simple words, ‘Je viens te chercher,’ took him home.
Here for a time he amused himself by sketching the portraits of
neighbours and relatives, but his desire to learn was unquenched, and
within a short time he entered as a student at the Royal College of
Franche-Comté at Besançon. This picturesque town, situated only thirty
miles from Arbois, was within easy reach of his home; and, above all, on
market days his father came thither to sell his leather.
At eighteen Pasteur received the degree of Bachelier ès Lettres, and
almost immediately was occupied in teaching others; but Paris, although
once abandoned, was again asserting its powers of attraction, and by the
autumn of 1842 he was once more following the courses at the Lycée
Saint-Louis. He also attended the brilliant lectures of Dumas at the
Sorbonne, and vividly describes the scene: ‘An audience of seven or
eight hundred listeners, the too frequent applause, everything just like
a theatre.’ At the end of his first year in Paris he achieved his great
ambition, and succeeded in entering the École Normale, and entering it
with credit.
For the last year or two Pasteur had been studying mathematics and
physics; at the École Normale he especially devoted himself to
chemistry. Under the teaching of Dumas and of Balard his enthusiasm
redoubled, and he passed his final examinations with distinction. Balard
was indeed a true friend. Shortly after the end of his career at the
École Normale, the Minister of Public Instruction nominated Pasteur to a
small post as teacher of physics at the Lycée of Tournon. But banishment
from Paris meant banishment from a laboratory. Balard intervened,
interviewed the Minister, and ended by attaching Pasteur to his staff of
assistants.
It must always be remembered that Pasteur was trained as a
chemist--_was_, in fact, a chemist. In afterlife he attacked problems
proper to the biologist, the physiologist, the physician, the
manufacturer; but he brought to bear on these problems, not the
intellect of one trained in the traditions of natural science, medicine,
or commerce, but the untrammelled intelligence of a richly-endowed mind,
‘organized common sense’ of the highest order. After the legal, there
is, perhaps, no learned profession so dominated by tradition, by what
our fathers have taught us, as the medical; and the advances in
preventive medicine which will ever be connected with Pasteur’s name owe
at least something to the fact that he was unfettered by any traditions
of professional training or etiquette. Passing from the diseases of the
lowest of the fungi to those of a caterpillar, a fowl, a sheep, until he
reached those of man himself, it must be acknowledged that he approached
the art of healing along an entirely new path.
His first researches were purely chemical--‘On the Capacity for
Saturation of Arsenious Acid,’ ‘Studies on the Arsenates of Potassium,
Soda, and Ammonia’--but he had been early attracted to the remarkable
observations of Mitscherlich and others on the optical properties of the
crystals of tartaric acid and its salts. Ordinary tartaric acid
crystals, when dissolved in water, turn the plane of polarized light to
the right; but another kind of tartaric acid, called by Gay-Lussac
racemic acid, and by Berzelius paratartaric acid--as M. Vallery-Radot
remarks, the name does not matter, and each is equally terrifying to the
lay mind--leaves it unaffected. In spite of the different actions of the
solutions of these two acids on light, Mitscherlich held their chemical
composition to be absolutely identical.
This set Pasteur thinking. He repeated the experiments. On examining
the crystals of sodium-ammonium salt of racemic acid, he noticed that
certain facets giving a degree of asymmetry were always found on the
crystals of the optically active salts and acids. On examining the
crystals of the racemic acid, he did not find, as he had expected,
perfect symmetry; but he saw that, whilst some of the crystals showed
these facets to the right, others showed them to the left. In fact,
sodium-ammonium racemate consisted of a mixture of right-handed and
left-handed crystals, which neutralized one another as regards the
polarization of light, and were thus optically inactive. With infinite
patience Pasteur picked out the right from the left handed crystals, and
investigated the action of their solutions on polarized light. As he
expected, the one sort turned the plane of polarization to the left, the
other to the right. A mixture of equal weights of the two kinds of
crystals remained optically inactive. ‘Tout est trouvé!’ he exclaimed;
and rushing from the laboratory, embraced the first man he came across.
‘C’était un peu comme Archimède,’ as his biographer gravely remarks.
His work immediately attracted attention. Biot, who had devoted a long
and strenuous life to the problems of polarization, was at first
sceptical, but, after a careful investigation, was convinced. Pasteur
began to be talked about in the circle of the Institute.
In the midst of these researches Pasteur’s mother died suddenly, and her
son, overwhelmed with grief, remained for weeks almost silent and unable
to work. Shortly after this we find the old longing revived, and Pasteur
sought at any cost some post near Arbois, somewhere not quite out of the
reach of those he loved. Besançon was refused him, but at the beginning
of 1849 he replaced M. Persoz as Professor of Chemistry at Strasbourg.
The newly-appointed Rector of the Academy of Strasbourg, M. Laurent,
had already gained the respect and the affection of the professoriate.
He and his family were the centre of the intellectual life of the town.
Within a few weeks of his arrival Pasteur addressed to the Rector a
letter, setting forth in simple detail his worldly position, and asking
the hand of his daughter Marie in marriage. The wedding took place on
May 29, 1850, and there is a tradition that Pasteur, immersed in some
chemical experiment, had to be fetched from the laboratory to take his
part in the ceremony at the church. Never was a union more happy. From
the first Madame Pasteur, animated by the spirit of the Academy of
Science, which always prints ‘Science’ with a capital letter, not only
admitted, but approved the principle that nothing should interfere with
the laboratory; whilst, on his side, Pasteur always flew to his wife to
confide in her first of all any new discovery, any new advance he had
made in his researches. During the five years passed at Strasbourg
Pasteur continued to work on the borderline between chemistry and
physics. His work on the polarization of light of the tartaric acid
crystals led him into the question of the arrangement of the atoms
within the molecule. ‘Il éclaire tout ce qu’il touche!’ exclaimed the
once sceptical but now convinced Biot; and it is hardly too much to say
that his researches were the starting-point of the new department of
physics which, under the name of stereo-chemistry, has attained vast
developments during the last quarter of the past century. These
researches were rewarded by the French Government, which in 1853
conferred on him the ribbon of the Legion of Honour, and received the
recognition of our own Royal Society, which rewarded him in 1856 the
Rumford medal.
It was whilst working at his beloved tartrates that he made an
observation which first directed his attention towards the problems of
fermentation. A German firm of manufacturing chemists, of whom there
were many in the neighbourhood of Strasbourg, noticed that impure
commercial tartrates of lime, when in contact with organic matter,
fermented if the weather were warm. Pasteur tested this, and found that,
when racemic acid is fermented under ordinary conditions, it is only the
right-handed variety that is affected; and he suggests that this is
probably the best way in which to prepare the left-handed acid.
Before dealing with Pasteur’s work on fermentation it is well to recall
how the matter stood when he began to study it. From the earliest period
fermentation had attracted the attention of mankind, but the first
record of an attempted explanation is that of Basilius Valentinus, a
Benedictine monk and alchemist, who lived at Erfurt during the latter
half of the fifteenth century. He was, perhaps, more of a pharmacologist
than a chemist, but we owe to him the introduction of hydrochloric acid,
which he made from oil of vitriol and salt. In his view alcohol existed
in the wort before fermentation began, and fermentation was a process of
purification of this alcohol, in which the yeast played the part of the
impurities. About a century later van Helmont, a well-to-do physician of
Vilvorde, near Brussels, a kind of regenerate Paracelsus, noted that
when fermentation occurs ‘gas’ is set free. It was van Helmont, indeed,
who invented the word ‘gas.’ Of the half-dozen words invented by
man--not derived, but created--‘gas’ is the one which has most surely
come to stay. Curiously enough, van Helmont’s predecessor, Paracelsus,
also invented two words which have, without the permanency of ‘gas,’
passed into current, though somewhat infrequent, use. They are ‘gnome’
and ‘sylph,’ the latter, perhaps, best known as recalling the outline of
Miss Henrietta Petowker in her palmier days. By his new term ‘gas’ van
Helmont did not mean an air or vapour, still less did he mean an
illuminant. He understood by this term carbon dioxide, and he points out
that when sugary solutions ferment, this gas is given off.
About 1700 Stahl, returning to a view put forward by Willis in 1659,
propounded the first physical view of fermentation. The ferment was to
their minds a body with a certain internal motion which it transmitted
to the fermentable matter. Stahl extended this view to the processes of
putrefaction and decay. One hundred years later Gay-Lussac taught that
the fermentation was set up by the presence of oxygen. The yeast-cells
had been seen and described by Leeuwenhoek as far back as 1675, but they
seem to have attracted little attention; and it was not until Schwann
published his researches, the earliest of which is dated 1837, and until
Cagniard de Latour, about the same date, put forward his vitalistic
theory--the theory which attributes fermentation to the action of living
organisms--that they were recognized as playing an important part in
fermentations. Even then they were not allowed to hold the field. Liebig
brought the weight of his great authority to oppose the vitalistic
theory. In his view the ferment was an unstable organic compound easily
decomposed, which in decomposing shook apart the molecules of the
fermenting material. This theory and that of Berzelius, who regarded
fermentation as a contact action due to some ‘catalytic’ force, divided
between them the allegiance of the chemical world, when, in the year
1854, Pasteur was nominated Professor and Dean of the new Faculty of
Science at Lille.
Here, in the centre of the beetroot industry, Pasteur had ample
opportunity to study the preparation of alcohol. The father of one of
his students owned a distillery, and suffered occasional loss from the
fermentations turning sour owing to the formation of lactic acid. He
was willing to place material at the disposal of the Professor; and
Pasteur made endless experiments, microscopic researches, notes, and at
length had the satisfaction of isolating the organism which produces the
lactic acid fermentation, and of proving that that, and that alone, was
capable of setting up this particular form of fermentation. Whilst in
the middle of his investigations on milk and the cause of its turning
sour, Pasteur was summoned to return to Paris, and installed as
scientific Director at his old college, the École Normale.
This was in 1857. The second Empire was at its zenith, and the
Government had little money to spend on science. Pasteur had to install
his laboratory in a garret, without even a boy to aid him. In this
garret he completed his work on alcohol fermentation, proved it to be
‘un acte corrélatif d’un phénomène vital, d’une organisation de
globules.’ During this work he noted a fact hitherto overlooked. It was
that the alcoholic fermentation is accompanied by the formation of small
quantities of glycerine and of succinic acid, which had up till that
date escaped the notice of chemists.
During the seven years which followed, Pasteur was ceaselessly engaged
in investigations on fermentation and on all those processes for which
micro-organisms are responsible. Whilst researching on the cause of
butyric acid formation, he discovered the remarkable fact that the
_Bacillus butyricus_, which causes the unpleasant flavour in rancid
butter, will not grow in the presence of free oxygen. Until this
discovery it had been accepted as an axiom that all living beings,
plants as well as animals, require free oxygen for the manifestation of
their energies. Here, however, was a bacillus which not only did without
oxygen but was injured by its presence. This observation, it is needless
to remark, excited much adverse criticism in the scientific world; but,
as usual, Pasteur was in the right. From the conditions under which they
grow he suggested the name ‘anaerobic’ for such bacteria as _B.
butyricus_; and later observers have shown that many pathogenic
micro-organisms are anaerobic. At the present day bacilli are usually
divided into two groups, those which grow in the presence of free oxygen
(aerobic), and those which will not grow in the presence of oxygen
(anaerobic).
Naturally the question of spontaneous generation occupied much of
Pasteur’s time. The view, that in certain circumstances living matter
originates from non-living, lasted from the classical times until
towards the end of the last century. The size of the animal so produced
varied, however, inversely with the growth of our era. Van Helmont in
the seventeenth century had a recipe for producing mice. Place a piece
of linen somewhat soiled in a vessel, add some grains of corn, flavour
with a piece of cheese, and in twenty-one days the mice will be there,
fully adult and of both sexes.
About the time that van Helmont died there was coming to the front in
Florence a young Italian poet, born at Arezzo--in whose cathedral he now
lies buried--who had a singular turn for investigating the secret
workings of organic nature. Francesco Redi--his name is immortalized in
the little larva Redia--was courtier, poet, doctor, above all zoologist;
and he belonged to that comparatively small section of teetotallers who
have enthusiastically sung the merits of wine.[3] By a series of
accurate experiments, such as nowadays are performed by every cook,
Redi proved conclusively that meat did not spontaneously produce flies.
Shortly afterwards Vallisnieri of Padua demonstrated that fruit did not
of itself give rise to grubs. In fact, unless an insect deposited its
egg in the fruit, there were no grubs.
The use of the microscope, however, lent a fresh vigour to the believers
in spontaneous generation; and, forced to relinquish the mouse and the
insect, they still found satisfaction in germs. In the middle of the
eighteenth century the doctrine was firmly upheld by an English priest,
one Needham, whose experiments, in spite of the keen, and as we now
know, unanswerable criticisms of the Abbé Spallanzani, were so
convincing that he was early elected a Fellow of the Royal Society. From
his time till late in the last century, the question of the spontaneous
origin of microscopic life has from time to time troubled the mind of
man. Pasteur, Tyndall, and others have at length laid that ghost. It
would take too much space to discuss all the experiments made to solve
this question. Pasteur’s work did not escape the liveliest criticism;
and eventually, in order to settle the matter, he appealed to the
Academy of Sciences to appoint a Commission to report on the experiments
of himself and his opponents. It is needless to say that when the
Committee met and inspected the experiments of Pasteur, and listened to
the excuses of his critics, they pronounced absolutely in favour of
Pasteur.
In 1862 Pasteur succeeded Senarmont as a member of the Academy of
Sciences; and, it is interesting to note, he was presented by the
mineralogical section. During this year he had interested himself in the
manufacture of vinegar, which is extensively carried on in and around
Orleans. He investigated the action of the _Mycoderma aceti_, the mould
whose activity converts alcohol into acetic acid; and he taught the
manufacturers the importance of pure cultures, showing them how, by a
careful manipulation of the temperature, and by artificially sowing the
fungus which effects the chemical change, the product they sought could
be produced in a week or ten days, instead of requiring two or three
months. This problem naturally led on to the acetous fermentation of
wine, the cause of great loss to French wine exporters. Pasteur was able
to demonstrate that the sourness of wine is caused by various foreign
organisms, each of which causes a peculiar flavour to appear in the wine
it attacks. The bouquet of wine is notoriously a delicate object, easily
disturbed; and the question arose how to check the growth of the
organisms without interfering with the bouquet. Pasteur solved it as he
solved similar problems with regard to milk. He was able to show that
after wine is properly oxygenated, if it be heated to a temperature of
some 55° to 60° C. the acid-forming micro-organisms are destroyed,
whilst the bouquet is unaffected. Perhaps one of Pasteur’s greatest
triumphs was his success in demonstrating this to a representative
assemblage of wine-tasters, notoriously a very opinionative class of
people.
Pasteur’s researches on micro-organisms further had a profound influence
on operative surgery. To the presence of bacteria is due many of the
dangers which used to follow on operations. If precautions are taken to
exclude the harmful germs much suffering and danger are avoided. It was
about this date--namely, in the spring of 1865--that Dr. (now Lord)
Lister, who nobly acknowledged the debt he owed to Pasteur, performed
his first operations under antiseptic treatment at the Glasgow
Infirmary. This date marks an epoch in the history of human suffering.
The chemist Dumas was about this time a member of the French Senate,
and in 1865 was charged with the duty of reporting on the petition of
some 3,500 ‘propriétaires des Départements séricicoles’ on an epidemic
which had for some years been destroying the silkworms of Southern
France. Dumas was a native of Alais, a town of the Département Gard,
situated in the centre of the silkworm industry, where also the
distinguished zoologist Quatrefages was born. Anything that affected
Alais affected Dumas; and the epidemic was destroying the prosperity of
his native town. The disease was indeed becoming serious. Already in
1849 the silkworms were sickening. The stage at which the symptoms
appeared varied--sometimes the eggs were sterile; at other times the
silkworms hatched out but to die. If they survived they became shiny;
black spots showed themselves; the worms moved with difficulty, refused
to eat, and perished; or, if they lived long enough to pupate, the pupa
either perished or the moth emerged in an enfeebled state and promptly
died.
Efforts had been made to improve the stock by importing eggs from Spain
and Portugal, but the Peninsula was soon affected. Eggs were then
fetched from Turkey, Greece, and the adjacent islands. These countries
too becoming infected, the French cultivators sent further afield and
brought eggs from Syria and the Caucasus. Even this resource failed
them, and in 1864 every silk-producing country in the world was
infected, with the solitary exception of Japan. The loss to commerce was
prodigious. In a normal year the value of the cocoons produced in
Southern France is, roughly speaking, about £4,000,000; in the years
1863 and 1864 it had fallen below £1,000,000.