The theory of gravitation, the theory of undulation, the theory of
evolution, the dynamical theory of heat--all had to push their way
through conflict to victory. And so it has been with the Germ Theory of
communicable diseases. Some outlying members of the medical profession
dispute it still. I am told they even dispute the communicability of
cholera. Such must always be the course of things, as long as men are
endowed with different degrees of insight. Where the mind of genius
discerns the distant truth, which it pursues, the mind not so gifted
often discerns nothing but the extravagance, which it avoids. Names,
not yet forgotten, could be given to illustrate these two classes of
minds. As representative of the first class, I would name a man whom
I have often named before, who, basing himself in great part on the
researches of Pasteur, fought, in England, the battle of the germ
theory with persistent valour, but whose labours broke him down before
he saw the triumph which he _fore_saw completed. Many of my medical
friends will understand that I allude here to the late Dr. William
Budd, of Bristol.
The task expected of me is now accomplished, and the reader is here
presented with a record, in which the verities of science are endowed
with the interest of romance.
JOHN TYNDALL.
ROYAL INSTITUTION: _December 1884_
FOOTNOTES:
[2] Art. 'Vitality,' _Fragments of Science_, 6th edit., vol. ii. p. 50.
[3] In Faraday's _induced_ dissymmetry the ray, having once passed
through the body under magnetic influence, has its rotation doubled,
instead of neutralised, as in the case of quartz, on being reflected
back through the body. Marbach has discovered that chlorate of soda
produces circular polarisation in all directions through the crystal,
while in quartz it occurs only in the direction of the axis. Marbach
also discovered facets upon his crystals, resembling those of quartz.
[4] It was late in the day when the Royal Society made him a foreign
member.
[5] These words were uttered at a time when the pythogenic theory was
more in favour than it is now.
[6] The work on _Diseases of Silkworms_ was dedicated to the Empress of
the French.
_RECOLLECTIONS OF CHILDHOOD AND YOUTH._
FIRST DISCOVERIES.
'Come, M. Pasteur! you must shake off the demon of idleness!' It was
the night watcher of the College of Besançon, who invariably at four
o'clock in the morning entered Pasteur's room and roused him with this
vigorous salute, which was accompanied, when necessary, by a sound
shaking. Pasteur was then eighteen years of age. In addition to his
food and lodging, the royal college paid him twenty-four francs a
month. But if his place was a modest one, it sufficed at the time for
his ambition: it was the first tie which bound him to the University.
'Ah,' said his father to him frequently, 'if only you could become some
day professor in the College of Arbois I should be the happiest man on
earth.'
Already, when he resided at Dôle, and when his son was not yet two
years old, this father permitted himself to dream thus of the future.
What would he have said had it been announced to him that fifty-eight
years later, on the façade of the little house in the Rue des Tanneurs,
would be placed, in the presence of his living son--laden with honours,
laden with glory, passing in the midst of a triumphal procession along
the paved town--a plate bearing these words in letters of gold:
HERE WAS BORN LOUIS PASTEUR,
_December 27, 1822._
Pausing before this house, Pasteur recalled the image of his father and
mother--of those whom he called his dear departed ones--and from the
far-off depths of his childhood came so many memories of affection,
devotion, and paternal sacrifices that he burst into tears.
The life of his father had been a rough one. An old soldier, decorated
on the field of battle, on returning to France, where he had no longer
a home, he was obliged to work hard to earn his bread. He took up the
trade of a tanner. Soon afterwards, having made the acquaintance of
a worthy young girl, he joined his lot with hers, and together they
entered courageously on the labours of their married life--he calm,
reflective, and more eager, whenever he had a moment of repose, for the
society of books than for the society of his neighbours; she full of
enthusiasm, her heart and spirit agitated by thoughts above the level
of her modest life. Both of them watched with ceaseless solitude over
their little Louis, of whom, with mingled pride and tenderness, they
used to say, 'We will make of him an educated man.'
In 1825 the Pasteur family quitted Dôle and established themselves
at Arbois, where, on the borders of the Cuisance, the father of our
hero had bought a small tanyard. At this town, and in this yard,
Louis Pasteur spent his childhood. As soon as he was old enough to be
received as a half-pay scholar he was sent to the communal college. He,
the smallest of all the pupils, was so proud of passing under the great
arched doorway of this ancient establishment, that he arrived laden
with enormous dictionaries, of which there was no need.
In the midst of his laborious occupations the father of Pasteur took
upon himself the task of superintending his son's lessons every
evening. This was at first no sinecure. Louis Pasteur did not always
take the shortest road either to reach his class or to return to his
work at home. Some old friends still living remember having made with
the little Pasteur fishing parties, which proved so pleasant that they
have been continued to the present day. The boy, moreover, instead of
applying himself to his lessons, often escaped and amused himself by
making large portraits of his neighbours, male and female. A dozen of
these portraits are still to be seen in the houses of Arbois, all
bearing his signature. Considering that his age at the time was only
thirteen, the accuracy of the drawing is astonishing.
'What a pity,' said an old lady of Arbois a short time since, 'that he
should have buried himself in chemistry! He has missed his vocation,
for he might by this time have made his reputation as a painter.'
It was not until he reached the third class that Louis Pasteur,
beginning to realise the sacrifices which his father imposed upon
himself, determined to abandon his fishing implements and his crayons,
feeling aroused within him that passion for work which was to form the
foundation of his life. The Principal of the college, who followed with
watchful interest the progress of a pupil who, in his first effort, had
outstripped all his comrades, used to say, 'He will go far. It is not
for the chair of a small college like ours that we must prepare him; he
must become professor in a royal college. My little friend,' he would
add, 'think of the great École Normale.'
The College of Arbois having no professor of philosophy, Pasteur
quitted it for Besançon. There he remained for the scholars' year,
received the degree of _bachelier ès lettres_, and was immediately
appointed tutor in the same college. In the intervals of his duties
he followed the course of mathematics necessary to prepare him for
the scientific examinations of the École Normale. He must have been
already endowed with a singular maturity of character, for the
director confided to him the superintendence of the quarters of the
older pupils, who during class time were his comrades. In the class
room his table was in the midst of them; and never had so young a
master so much authority, and at the same time so little need for its
exercise.
His first taste for chemistry manifested itself by frequent questions
addressed during class time to an old professor named Darlay. This
questioning was so often repeated that the good man, quite bewildered,
ended by declaring that it was for him to interrogate Pasteur and not
for Pasteur to interrogate him. His pupil pressed him no further, but
having heard that at Besançon there lived an apothecary who had once
distinguished himself by a paper inserted in the 'Annales de Chimie et
de Physique,' he sought this man, with a view of ascertaining whether,
on holidays, he would consent to give him lessons secretly.
At the examination for the École Normale, Pasteur passed as fourteenth
in the list. This rank, however, did not satisfy him. Notwithstanding
the censure of his fellow candidates he declared that he would begin
a new year of preparation. It was in Paris itself that he chose to
work--in one of the silent corners of the city, amid the seclusion of
preparatory schools and convents.
In the Impasse des Feuillantines, there lived a schoolmaster, M.
Barbet by name, or rather _le père Barbet_, as the Franc-Comtois,
with provincial familiarity, used to call him. Pasteur begged to be
allowed to enter his institution, not as an assistant, but as a simple
pupil. Knowing how slender were the means of his young compatriot, M.
Barbet reduced the fees of his pupil by one-third. Such kindness was
customary with the _père Barbet_, who did not like to be reminded of
his generosity. This, however, gives double pleasure to him who records
it.
The year passes, the time of the examination arrives, and Pasteur is
received as fourth on the list. Thus at last, in the month of October
1843, he finds himself in that École Normale in which he was destined
to take so great a place. Pasteur's taste for chemistry had become a
passion which he could now satisfy to his heart's content. Chemistry
was at this time taught at the Sorbonne by M. Dumas and at the École
Normale by M. Balard. The pupils of the École attended both courses of
lectures. Different as were the two professors, both of them exercised
great influence on their pupils. M. Dumas, with his serene gravity
and his profound respect for his auditory, never allowed the smallest
incorrectness to slip into his exposition. M. Balard, with a vivacity
quite juvenile, with the excitement of a southerner in the tribune, did
not always give his words time to follow his thoughts. It was he who
once, showing a little potash to his audience, exclaimed with a fervour
which has become celebrated, 'Potash, which--potash, then--potash, in
short, which I now present to you.'
The general principles which M. Dumas in his teaching delighted to
develop, the multitude of facts which M. Balard unfolded to his pupils,
all answered to the needs of Pasteur's mind. If he loved the vaster
horizons of science, he was also possessed by the anxious desire
for exactitude, and for the perpetual control of experiment. Each
of the lectures of the École Normale and of the Sorbonne excited in
him a profound enthusiasm. One day M. Dumas, while illustrating the
solidification of carbonic acid, begged for the loan of a handkerchief
to receive the carbonic acid snow. Pasteur rushed forward, and,
presenting his handkerchief, received the snow. He returned triumphant,
and running forthwith to the École Normale, repeated the principal
experiments which the illustrious chemist had just exhibited to his
audience. He preserved religiously the handkerchief which had been
touched by M. Dumas.
Pasteur usually spent his Sundays with M. Barruel, the assistant of M.
Dumas. He thought of nothing but experiments. For a long time in one of
the laboratories of the École Normale was exhibited a basin--perhaps
it is still shown--containing sixty grammes of phosphorus obtained
from bones bought at the butcher's by Pasteur. These he had calcined,
submitted to the processes known to chemists, and finally reduced,
after a whole day's heating, from four in the morning to nine in the
evening, to the said sixty grammes. It was the first time that the long
manipulations required in the preparation of this simple substance were
attempted at the École Normale.
Isolated in laboratory or library, Pasteur's only thought was to
search, to learn, to question, and to verify. As the rule of the school
leaves much to individual initiative, he devoted himself to his work
with a joyful heart. This daily liberty constitutes the charm and the
honour of the École Normale. Not only does it permit but it encourages
individual effort; it allows the student to visit at his will the
library, and to consult there the scientific journals and reviews. This
free system of education develops singularly the spirit of research.
There is in it an element of superiority over the École Polytechnique.
Influenced by its military origin, constrained, moreover, by the number
of its pupils to impose on all an exact discipline, and to introduce
into their exercises a strict regularity, the École Polytechnique is,
perhaps, less calculated than the École Normale to awaken in the minds
of its pupils a taste for speculative science. It is certain that
Pasteur owed to the freedom of work, and to the facilities for solitary
reading which he there enjoyed, the first occasion for an investigation
which was the starting-point to a veritable discovery.
I.
Unlike the old professor of physics and chemistry at Besançon, one
of the lecturers in the École Normale often took pleasure, not only
in answering Pasteur's questions, but in leading him on to talk over
scientific subjects. M. Delafosse, whose memory remains dear to all
his pupils, was one of those men who fail to do themselves justice, or
who, according to the expression of Cardinal de Retz, do not fulfil
all their merit. Not that circumstances have been unfavourable to
them, but that an invincible modesty, and a natural nonchalance which
finds in that modesty a shield against latent self-reproach, leave
them in a sort of twilight in which they are content to dwell. Pupil,
and afterwards fellow worker, of the celebrated crystallographer Haüy,
M. Delafosse had devoted himself to questions of molecular physics.
Pasteur, who had read with enthusiasm the works of Haüy, conversed
incessantly with Delafosse about the arrangements of molecules, when an
unexpected note from the German chemist Mitscherlich, communicated to
the Academy of Sciences, came to trouble all his scientific beliefs.
Here is the note:--
'The paratartrate and the tartrate of soda and ammonia have the same
chemical composition, the same crystalline form, the same angles, the
same specific weight, the same double refraction, and consequently
the same inclination of the optic axes. Dissolved in water, their
refraction is the same. But while the dissolved tartrate causes the
plane of polarised light to rotate, the paratartrate exerts no such
action. M. Biot has found this to be the case with the whole series of
these two kinds of salts. Here (adds Mitscherlich) the nature and the
number of the atoms, their arrangement, and their distances apart are
the same in the two bodies.'
Imbued as he was with the teachings of Haüy and Delafosse, and full of
the ideas of M. Dumas in molecular chemistry, Pasteur asked himself
this question: 'How can it be admitted that the nature and number of
the atoms, their arrangement and distances apart, in two chemical
substances are the same; that the crystalline forms are equally the
same, without concluding that the two substances are absolutely
identical? Is there not a profound incompatibility between the identity
affirmed by Mitscherlich and the discrepancy of optic character
manifested by the two compounds, tartaric and paratartaric, which form
the subject of his note?'
This difficulty rested in Pasteur's mind with the tenacity of a fixed
idea. Received as _agrégé_ of physical science at the end of his third
year at the École, and then keeping near his master, M. Balard, he had
begun the study of crystals and the determination of their angles and
forms, when his nomination to the professorship of physics in the Lycée
of Tournon surprised and distressed him. M. Balard repaired immediately
to the bureau of the Minister of Education, and spoke of his assistant
in terms which caused the nomination to be cancelled. Pasteur remained
in the laboratory of the École Normale.
With a view to mastering the science of crystallography, he took for
his guide the extensive work of M. de la Provostaye, resolving to
repeat all the measurements of angles and all the other determinations
of this author with a view to a comparison of their respective
results. The work of M. de la Provostaye, who was distinguished by the
exactitude of his researches, had for its subject the tartaric and
paratartaric acids and their saline compounds.
* * * * *
Two or three years ago, while we were walking together along a road in
the Jura, M. Pasteur, after quoting textually the note of Mitscherlich,
described to me with enthusiasm the pleasure he had experienced in
crystallising tartaric acid and its salts, the crystals of which, he
said, rivalled in size and beauty the most exquisite of crystalline
forms.
'I should have great difficulty,' I remarked, 'in following you through
the labyrinth of tartaric acid, tartrates, and paratartrates. However
much your other studies have attracted me, those which had for their
starting-point the note of Mitscherlich and the memoir of M. de la
Provostaye have appeared to me, whenever I tried to master them,
difficult of access. Ah,' I added, 'you would have done well, out of
consideration for those who love to speak of your labours, had you made
no discoveries in this field.'
Pasteur, with a mixture of indignation and indulgence, replied:--'Is it
possible that you have not discerned the grand horizons that lie behind
these researches in physics and molecular optics? If I have a regret,
it is that I did not follow out this path. Less rough than it at first
sight appears, it would, I am convinced, have led to the most important
discoveries. By a sudden turn it threw me unexpectedly upon the subject
of fermentation, and fermentation led me to the study of diseases; but
I still continue to lament that I have never had time to retrace my
steps.'
Then, with a simplicity of exposition in which one recognised the
teacher who had always endeavoured to place his ideas within the range
of his hearers, he said--
'If you picture to yourself all the bodies in nature--mineral, animal,
or vegetable, and consider even the objects formed by the hands of man,
you will see that they divide themselves into two great categories.
The one has a plane of symmetry and the other has not. Take, for
instance, a table, a chair, a playing die, or the human body; we can
imagine a plane passing through these objects which divides each of
them into two absolutely similar halves. Thus, a plane passing through
the middle of the seat and of the back of an arm-chair would have, on
its right and left, identical parts; in like manner a vertical plane
passing through the middle of the forehead, nose, mouth, and chin of
an individual, would have similar parts to the right and to the left.
All these objects, and a multitude of similar ones, constitute our
first category. They have, as mathematicians express it, one or several
planes of symmetry.
'But, as regards the repetition of similar parts, it is far from
being the case that all bodies are constituted in the manner here
described. Consider, for example, your right hand: it is impossible
to find for it a plane of symmetry. Whatever be the position of a
plane which you imagine cutting the hand, you will never find on the
right of this plane exactly the same as you find on its left. The same
remark applies to your left hand, to your right ear and to your left
ear, to your right eye and to your left eye; to your two arms, your
two legs, and your two feet. The human body, taken as a whole, has a
plane of symmetry, but none of the parts composing one or the other
of its halves has such a plane. The stalk of a plant whose leaves are
distributed spirally round its stem has not a plane of symmetry, nor
has a spiral staircase such a plane; but a straight one has. You see
this?
'It would have been truly extraordinary, would it not, if the various
kinds of minerals, such as sea salt, alum, the diamond, rock crystal,
and so many others which illustrate the great law of crystallisation,
and which clothe themselves in geometric forms, should not present to
us examples of the two categories of which we have just been speaking?
They do so in fact. Thus a cube, which has the form of a player's die,
has a plane of symmetry; it has indeed several planes. The form of
the diamond, which is a regular octahedron, has also several planes
of symmetry. It is thus also with the great majority of the mineral
forms met with in nature or in the laboratory. They have generally
one or several planes of symmetry. There are, however, exceptions.
Rock crystal, which is found in prisms, often of large volume, in the
fissures of certain primitive rocks, has no plane of symmetry. This
crystal exhibits certain small facets, distributed in such a manner
that in their totality they might be compared to a helix, or spiral, or
screw, which are all objects not possessing a plane of symmetry.
'Every object which has a plane of symmetry, when placed before a
looking-glass, has an image which is rigorously identical with the
object itself. The image can be superposed upon the reality. Place a
chair before a mirror; the image faithfully reproduces the chair. The
mirror also reproduces the human body considered as a whole. But place
before the mirror your right hand and you will see a left hand. The
right hand is not superposable on the left, just as the glove of your
right hand cannot be fitted to your left, and inversely.'
Then reverting to the beginnings of his studies in crystallography,
Pasteur recounted to me briefly that, after having gone through the
work of M. de la Provostaye, he perceived that a very interesting fact
had escaped the notice of this skilful physicist. M. de la Provostaye
had failed to observe that the crystalline forms of tartaric acid and
of its compounds all belong to the group of objects which have not a
plane of symmetry. Certain minute facets had escaped him. In other
words, Pasteur discerned that the crystalline form of tartaric acid,
placed before a mirror, produced an image which was not superposable
upon the crystal itself. The same was found to be true of the forms
of all the chemical compounds of this acid. On the other hand, he
imagined that the crystalline form of paratartaric acid, and of all the
compounds of this acid, would be found to form part of the group of
natural objects which have a plane of symmetry.
Pasteur was transported with joy by this double result. He saw in it
the possibility of reaching by experiment the explanation of the
difficulty which the note of Mitscherlich had thrown down as a kind of
challenge to science, when it signalised an optical difference between
two chemical compounds affirmed to be otherwise rigorously identical.
Pasteur reasoned thus:--Since I find tartaric acid and all its
tartrates without a plane of symmetry, while its isomer, paratartaric
acid, and its compounds have such a plane, I will hasten to prepare
the tartrate and the paratartrate of the note of Mitscherlich. I will
compare their forms, and in all probability the tartrate will be found
dissymmetrical--that is to say, without a plane of symmetry--while
the paratartrate will continue to have such a plane. Henceforward the
absolute identity stated by Mitscherlich to exist between the forms
of these two compounds will have no existence. It will be proved
that he has erred, and his note will no longer have in it anything
mysterious. As the optic action proper to the tartrates spoken of in
his note manifests itself by a deviation of the plane of polarisation
to the right, we have here a kind of dissymmetry which has nothing
incompatible with the dissymmetry of form. On the contrary, these
two dissymmetries can be referred to one and the same cause. In like
manner, the absence of dissymmetry in the form of the paratartrate will
be connected with the optical neutrality of that compound.