Part 1

LOUIS PASTEUR

LOUIS PASTEUR HIS LIFE AND LABOURS

_BY HIS SON-IN-LAW_

TRANSLATED FROM THE FRENCH BY LADY CLAUD HAMILTON

_WITH AN INTRODUCTION_ BY JOHN TYNDALL

NEW YORK D. APPLETON AND COMPANY 1, 3, AND 5 BOND STREET 1886.

PREFACE.

In the _salon_ of a distinguished man, or of a great writer, there is often to be found a person who, without being either a fellow-worker or a disciple, without even possessing the scientific or literary qualities which might explain his habitual presence, lives nevertheless in complete familiarity with the man whom all around him call 'dear master.' Whence comes this intimate one? who is he? what is his business? He is only known as a friend of the house. He has no other title, and he is almost proud of having no other. Stripped of his own personality, he speaks only of the labours and the success of his illustrious friend, in the radiance of whose glory he moves with delight.

The author of this work is a person of this description. Intimately connected with the life of M. Pasteur, and a constant inmate of his laboratory, he has passed happy years near this great investigator, who has discovered a new world--the world of the infinitely little. Since the first studies of M. Pasteur on molecular dissymmetry, down to his most recent investigations on hydrophobia, on virulent diseases, and on the artificial cultures of living contagia, which have been converted by such cultures into veritable vaccines--passing by the intermediate celebrated experiments on spontaneous generation, fermentation, the diseases of wine, the manufacture of beer and vinegar, and the diseases of silkworms--the author of these pages has been able, if not to witness all, at least to follow in its principal developments this uninterrupted series of scientific conquests.

'What a beautiful book,' he remarked one day to M. Pasteur, 'might be written about all this!'

'But it is all in the Comptes-rendus of the Academy of Sciences.'

'It is not for the readers of the Comptes-rendus that such a book needs to be written, but for the great public, who know that you have done great things, but who know it only vaguely, by the records of journals, or by fragments of biography. The persons are few who know the history of your discoveries. What was your point of departure? How have you arrived at such and such principles, and at the consequences which flow from these principles? What is the connection and rigorous bond of your method? These are the things which it would be interesting to put together in a book which would have some chance of enduring as an historic document.'

'I could not waste my time in going back upon things already accomplished.'

'No; but my desire is that someone else should consecrate his time to the work. And listen,' added this friend, with audacious frankness--'do you know by whom, in my opinion, this book ought to be written? By a man who, without having been in any way trained to follow in your footsteps, is animated by the most lively desire to understand the course which you have pursued; who, while living at your side, has been each day impregnated with your method and your ideas; who, having had the happiness of comprehending your life and its achievements, does not wish to confine the pleasure thus derived to himself alone.'

'Where, then,' interrupted Pasteur with a kindly smile, not without a tinge of irony, 'is this man, at once so happy, and so impatient to share his happiness with others?'

'He is now pleading his cause before you. Yes, I would gladly attempt such a work. I have seen your efforts and observed your success. The experiments which I have not witnessed you have always freely explained to me, with that gift of clearness which Vauvenargues called the "polish" of masters.[1] Initiated by affection, I would make myself initiator by admiration. It would be the history of a learned man by an ignorant one. My ignorance would save me from dwelling too strictly or too long on technical details. With the exposition of your doctrine I would mingle some fragments of your biography. I would pass from a discovery to an anecdote, and so arrange matters as to give the book not only the character of a familiar scientific conversation, which would hardly be more than the echo of what I have learnt while near you, but also to make it a reflex of your life.'

'You should postpone that until I am no longer here.'

'Why so? Why, before assigning to them their places, should we wait till those whose names will endure have disappeared from the scene? No; it is you, living, that I wish to paint--you, in full work, in the midst of your laboratory. And, in addition to all other considerations, I would add, that your presence in the flesh will be the guarantee of my exactitude.'

_July 1883._

FOOTNOTE:

[1] 'Vernis des maîtres.'

CONTENTS.

PAGE

INTRODUCTION, BY PROFESSOR TYNDALL xi

RECOLLECTIONS OF CHILDHOOD AND YOUTH--FIRST DISCOVERIES 1

FERMENTATION 40

ACETIC FERMENTATION-- THE MANUFACTURE OF VINEGAR 66

THE QUESTION OF SPONTANEOUS GENERATION 89

STUDIES ON WINE 112

THE SILKWORM-DISEASE 127

DECISIVE EXPERIMENTS 164

STUDIES ON BEER 168

VIRULENT DISEASES--SPLENIC FEVER, SEPTICÆMIA 176

FOWL CHOLERA 212

ATTENUATED VIRUS, OR VACCINATION-- THE FOWL CHOLERA VACCINE 220

THE VACCINE OF SPLENIC FEVER 231

THE RETURN TO VIRULENCE 246

ETIOLOGY OF SPLENIC FEVER 250

METHOD OF DISCUSSION AND CONTRADICTIONS 262

THE LABORATORY OF THE ÉCOLE NORMALE-- VARIOUS STUDIES--HYDROPHOBIA 271

INTRODUCTION.

In the early part of the present year the French original of this work was sent to me from Paris by its author. It was accompanied by a letter from M. Pasteur, expressing his desire to have the work translated and published in England. Responding to this desire, I placed the book in the hands of the Messrs. Longman, who, in the exercise of their own judgment, decided on publication. The translation was confided, at my suggestion, to Lady Claud Hamilton.

The translator's task was not always an easy one, but it has, I think, been well executed. A few slight abbreviations, for which I am responsible, have been introduced, but in no case do they affect the sense. It was, moreover, found difficult to render into suitable English the title of the original: '_M. Pasteur, Histoire d'un Savant par un Ignorant_.' A less piquant and antithetical English title was, therefore, substituted for the French one.

This filial tribute, for such it is, was written, under the immediate supervision of M. Pasteur, by his devoted and admiring son-in-law, M. Valery Radot. It is the record of a life of extraordinary scientific ardour and success, the picture of a mind on which facts fall like germs upon a nutritive soil, and, like germs so favoured, undergo rapid increase and multiplication. One hardly knows which to admire most--the intuitive vision which discerns in advance the new issues to which existing data point, or the skill in device, the adaptation of means to ends, whereby the intuition is brought to the test and ordeal of experiment.

In the investigation of microscopic organisms--the 'infinitely little,' as Pouchet loved to call them--and their doings in this our world, M. Pasteur has found his true vocation. In this broad field it has been his good fortune to alight upon a crowd of connected problems of the highest public and scientific interest, ripe for solution, and requiring for their successful treatment the precise culture and capacities which he has brought to bear upon them. He may regret his abandonment of molecular physics; he may look fondly back upon the hopes with which his researches on the tartrates and paratartrates inspired him; he may think that great things awaited him had he continued to labour in this line. I do not doubt it. But this does not shake my conviction that he yielded to the natural affinities of his intellect, that he obeyed its truest impulses, and reaped its richest rewards, in pursuing the line that he has chosen, and in which his labours have rendered him one of the most conspicuous scientific figures of this age.

With regard to the earliest labours of M. Pasteur, a few remarks supplementary to those of M. Radot may be introduced here. The days when angels whispered into the hearkening human ear, secrets which had no root in man's previous knowledge or experience, are gone for ever. The only revelation--and surely it deserves the name--now open to the wise arises from 'intending the mind' on acquired knowledge. When, therefore, M. Radot, following M. Pasteur, speaks with such emphasis about 'preconceived ideas,' he does not mean ideas without antecedents. Preconceived ideas, if out of deference to M. Pasteur the term be admitted, are the vintage of garnered facts. We in England should rather call them inductions, which, as M. Pasteur truly says, inspire the mind, and shape its course, in the subsequent work of deduction and verification.

At the time when M. Pasteur undertook his investigation of the diseases of silkworms, which led to such admirable results, he had never seen a silkworm; but, so far from this being considered a disqualification, M. Dumas regarded his freedom from preconceived ideas a positive advantage. His first care was to make himself acquainted with what others had done. To their observations he added his own, and then, surveying all, came to the conclusion that the origin of the disease was to be sought, not in the worms, not in the eggs, but in the moths which laid the eggs. I am not sure that this conclusion is happily described as 'a preconceived idea.' Every whipster may have his preconceived ideas; but the divine power, so largely shared by M. Pasteur, of distilling from facts their essences--of extracting from them the principles from which they flow--is given only to a few.

* * * * *

With regard to the discovery of crystalline facets in the tartrates, which has been dwelt upon by M. Radot, a brief reference to antecedent labours may be here allowed. It had been discovered by Arago, in 1811, and by Biot, in 1812 and 1818, that a plate of rock-crystal, cut perpendicular to the axis of the prism, possessed the power of rotating the plane of polarisation through an angle, dependent on the thickness of the plate and the refrangibility of the light. It had, moreover, been proved by Biot that there existed two species of rock-crystal, one of which turned the plane of polarisation to the right, and the other to the left. They were called, respectively, right-handed and left-handed crystals. No external difference of crystalline form was at first noticed which could furnish a clue to this difference of action. But closer scrutiny revealed upon the crystals minute facets, which, in the one class, were ranged along a right-handed, and, in the other, along a left-handed spiral. The symmetry of the hexagonal prism, and of the two terminal pyramids of the crystal, was disturbed by the introduction of these spirally-arranged facets. They constituted the outward and visible sign of that inward and invisible molecular structure which produced the observed action, and difference of action, on polarised light.

When, therefore, the celebrated Mitscherlich brought forward his tartrates and paratartrates of ammonia and soda, and affirmed them to possess the same atoms, the same internal arrangement of atoms, and the same outward crystalline form, one of them, nevertheless, causing the plane of polarisation to rotate, while the other did not, Pasteur, remembering, no doubt, the observations just described, instituted a search for facets like those discovered in rock-crystal, and which, without altering chemical constitution, destroyed crystalline identity. He first found such facets in the tartrates, while he subsequently proved the neutrality of the paratartrate to be due to the equal admixture of right-handed and left-handed crystals, one of which, when the paratartrate was dissolved, exactly neutralised the other.

Prior to Pasteur the left-handed tartrate was unknown. Its discovery, moreover, was supplemented by a series of beautiful researches on the compounds of right-handed and left-handed tartaric acid; he having previously extracted from the two tartrates, acids which, in regard to polarised light, behaved like themselves. Such was the worthy opening of M. Pasteur's scientific career, which has been dwelt upon so frequently and emphatically by M. Radot. The wonder, however, is, not that a searcher of such penetration as Pasteur should have discovered the facets of the tartrates, but that an investigator so powerful and experienced as Mitscherlich should have missed them.

The idea of molecular dissymmetry, introduced by Biot, was forced upon Biot's mind by the discovery of a number of liquids, and of some vapours, which possessed the rotatory power. Some, moreover, turned the plane of polarisation to the right, others to the left. Crystalline structure being here out of the question, the notion of dissymmetry, derived from the crystal, was transferred to the molecule. 'To produce any such phenomena,' says Sir John Herschel, 'the individual molecule must be conceived as unsymmetrically constituted.' The illustrations employed by M. Pasteur to elucidate this subject, though well calculated to give a general idea of dissymmetry, will, I fear, render but little aid to the reader in his attempts to realise _molecular_ dissymmetry. Should difficulty be encountered here at the threshold of this work, I would recommend the reader not to be daunted by it, or prevented by it from going further. He may comfort himself by the assurance that the conception of a dissymmetric molecule is not a very precise one, even in the mind of M. Pasteur.

One word more with regard to the parentage of preconceived ideas. M. Radot informs us that at Strasburg M. Pasteur invoked the aid of helices and magnets, with a view to rendering crystals dissymmetrical at the moment of their formation. There can, I think, be but little doubt that such experiments were suggested by the pregnant discovery of Faraday published in 1845. By both helices and magnets Faraday caused the plane of polarisation in perfectly neutral liquids and solids to rotate. If the turning of the plane of polarisation be a demonstration of molecular dissymmetry, then, in the twinkling of an eye, Faraday was able to displace symmetry by dissymmetry, and to confer upon bodies, which in their ordinary state were inert and dead, this power of rotation which M. Pasteur considers to be the exclusive attribute of life.

The conclusion of M. Pasteur here referred to, which M. Radot justly describes as 'worthy of the most serious consideration,' is sure to arrest the attention of a large class of people, who, dreading 'materialism,' are ready to welcome any generalisation which differentiates the living world from the dead. M. Pasteur considers that his researches point to an irrefragable physical barrier between organic and inorganic nature. Never, he says, have you been able to produce in the laboratory, by the ordinary processes of chemistry, a dissymmetric molecule--in other words, a substance which, in a state of solution, where molecular forces are paramount, has the power of causing a polarised beam to rotate. This power belongs exclusively to derivatives from the living world. Dissymmetric _forces_, different from those of the laboratory, are, in Pasteur's mind, the agents of vitality; it is they that build up dissymmetric molecules which baffle the chemist when he attempts to reproduce them. Such molecules trace their ancestry to life alone. 'Pourrait-on indiquer une séparation plus profonde entre les produits de la nature vivante, et ceux de la nature minérale, que cette dissymmétrie chez les uns, et son absence chez les autres?' It may be worth calling to mind that molecular dissymmetry is the _idea_, or _inference_, the observed rotation of the plane of polarisation, by masses of sensible magnitude, being the _fact_ on which the inference is based.

That the molecule, or unit brick, of an organism should be different from the molecule of a mineral is only to be expected, for otherwise the profound distinction between them would disappear. And that one of the differences between the two classes of molecules should be the possession, by the one, of this power of rotation, and its non-possession by the other, would be a fact, interesting no doubt, but not surprising. The critical point here has reference to the power and range of chemical processes, apart from the play of vitality. Beginning with the elements themselves, can they not be so combined as to produce organic compounds? Not to speak of the antecedent labours of Wöhler and others in Germany, it is well known that various French investigators, among whom are some of M. Pasteur's illustrious colleagues of the Academy, have succeeded in forming substances which were once universally regarded as capable of being elaborated by plants and animals alone. Even with regard to the rotation of the plane of polarisation, M. Jungfleisch, an extremely able pupil of the celebrated Berthelot, affirms that the barrier erected by M. Pasteur has been broken down; and though M. Pasteur questions this affirmation, it is at least hazardous, where so many supposed distinctions between organic and inorganic have been swept away, to erect a new one. For my part, I frankly confess my disbelief in its permanence.

Without waiting for new facts, those already in our possession tend, I think, to render the association which M. Pasteur seeks to establish between dissymmetry and life insecure. Quartz, as a crystal, exerts a very powerful twist on the plane of polarisation. Quartz dissolved exerts no power at all. The molecules of quartz, then, do not belong to the same category as the crystal of which they are the constituents; the former are symmetrical, the latter is dissymmetrical. This, in my opinion, is a very significant fact. By the act of crystallisation, and without the intervention of life, the forces of molecules, possessing planes of symmetry, are so compounded as to build up crystals which have no planes of symmetry. Thus, in passing from the symmetrical to the dissymmetrical, we are not compelled to interpolate new forces; the forces extant in mineral nature suffice. The reasoning which applies to the dissymmetric crystal applies to the dissymmetric molecule. The dissymmetry of the latter, however pronounced and complicated, arises from the composition of atomic forces which, when reduced to their most elementary action, are exerted along straight lines. In 1865 I ventured, in reference to this subject, to define the position which I am still inclined to maintain. 'It is the compounding, in the organic world, of forces belonging equally to the inorganic that constitutes the mystery and the miracle of vitality.'[2]

Add to these considerations the discovery of Faraday already adverted to. An electric current is not an organism, nor does a magnet possess life; still, by their action, Faraday, in his first essay, converted over one hundred and fifty symmetric and inert aqueous solutions into dissymmetric and active ones.[3]

Theory, however, may change, and inference may fade away, but scientific experiment endures for ever. Such durability belongs, in the domain of molecular physics, to the experimental researches of M. Pasteur.

* * * * *

The weightiest events of life sometimes turn upon small hinges; and we now come to the incident which caused M. Pasteur to quit a line of research the abandonment of which he still regrets. A German manufacturer of chemicals had noticed that the impure commercial tartrate of lime, sullied with organic matters of various kinds, fermented on being dissolved in water and exposed to summer heat. Thus prompted, Pasteur prepared some pure, right-handed tartrate of ammonia, mixed with it albuminous matter, and found that the mixture fermented. His solution, limpid at first, became turbid, and the turbidity he found to be due to the multiplication of a microscopic organism, which found in the liquid its proper aliment. Pasteur recognised in this little organism a _living ferment_. This bold conclusion was doubtless strengthened, if not prompted, by the previous discovery of the yeast-plant--the alcoholic ferment--by Cagniard-Latour and Schwann.

Pasteur next permitted his little organism to take the carbon necessary for its growth from the pure paratartrate of ammonia. Owing to the opposition of its two classes of crystals, a solution of this salt, it will be remembered, does not turn the plane of polarised light either to the right or to the left. Soon after fermentation had set in, a rotation to the left was noticed, proving that the equilibrium previously existing between the two classes of crystals had ceased. The rotation reached a maximum, after which it was found that all the right-handed tartrate had disappeared from the liquid. The organism thus proved itself competent to select its own food. It found, as it were, one of the tartrates more digestible than the other, and appropriated it, to the neglect of the other. No difference of chemical constitution determined its choice; for the elements, and the proportions of the elements, in the two tartrates were identical. But the peculiarity of structure which enabled the substance to rotate the plane of polarisation to the right, also rendered it a fit aliment for the organism. This most remarkable experiment was successfully made with the seeds of our common mould, _Penicillium glaucam_.