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 Pasteur 
 
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THE (I'JNTUItY SCIENCE SERIES. 
 
 Edited by SIR HENRY E. ROSCOE, D.O.L., LL D.. F.R.S. 
 
 PASTEUR 
 
The Century Science Series. 
 
 EDITED RV 
 
 SIR HENRY E. ROSCOE, D.C.L., F.R.S. 
 
 Pasteur. 
 
 By Percy Frankland, F.R.S., and Mrs. Percy 
 
 Frankland. 
 
 John Dalton and the Rise of Modem Chemistry. 
 
 By Sir Henry E. Roscoe, F.R.S. 
 
 Major Rennell, F.R.S., and the Rise of Modem 
 English Geography. 
 
 By Sir Clemknts R. Markham, C. B., F.R.S., President 
 of the Royal Geographical Society. 
 
 Justus von Liebig : his Life and Work (1803-1873). 
 
 By W. A. Shenstone, F.I.C, Lecturer on Chemistry in 
 
 Clifton College. 
 
 The Herschels and Modem Astronomy. 
 
 By Agnes M. Clerkr, Author of "A Popular Hi.story 
 of Astronomy during the igth Century," &c. 
 
 Charles Lyell and Modem Geology. 
 
 By Professor T. G. Bonney, F.R.S., &c. 
 
 James Clerk Maxwell and Modern Physics. 
 
 By R. T. Glazebrook, F.R.S., Fellow of Trinity College, 
 Cambridge. 
 
 Humphry Davy, Poet and Philosopher. 
 
 By r. E. Thorpe, LL.D., F.R.S. 
 
 Charles Darwin and the Theory of Natural 
 Selection. 
 
 By Edward B. Poulton, M.A., F.R.S., Hope Professor 
 of Zoology at the University of Oxford, &c. 
 
 In Preparation. 
 
 Michael Faraday : his Life and Work. 
 
 By Professor Silvanus P. Thompson, F.R.S. 
 CASSELL <fe COMPANY, Limited, Z,^«^^m; Paris &> Melbourne. 
 
LOUIS PASTEUR. 
 
 [Froittisjnece. 
 

 THE CENTURY SCIENCE SERIES 
 
 PASTEUR 
 
 BY 
 
 PERCY FRANKLAND 
 
 Ph.D. (Wiirzljurg), B.Sc. (London), F.E.S. 
 
 Associate Royal School of Mines, Fellow of the Institute of Chemistry, Formerly 
 Professor of Cltemistry in University College, Dundee ; Professor of 
 Chemistry in Mason University College, Birmingham 
 
 AND 
 
 Mrs. PERCY FRANKLAND 
 
 Authors of ^'■Micro-organisms in Water," etc. etc. 
 
 "The first point of wisdom is to discern that which is false; 
 the second, to know that which is ti-ue." — Lactantius 
 
 CASSELL AND COMPANY, Limited 
 
 LONDON, PARIS i' MELBOURNE 
 
 1898 
 
 ALL RIGHTS RESERVED 
 
V 
 
 
 TVuJ 
 
PREFACE. 
 
 In the following pages we have endeavoured to 
 present a sketch of the life and work of one of the 
 most remarkable men of science this century has pro- 
 duced. His achievements are so interwoven with the 
 circumstances by w^hich our dail}^ life is surrounded, 
 that it is all but impossible to find anyone who is 
 not directly or indirectly concerned with some part 
 or other of his great life-work. 
 
 But although the lives of so many have been 
 profoundly affected by his genius and labours, it is 
 only the few who have any acquaintance with the 
 man and the method, to whom and to which these 
 great achievements are due. 
 
 It is our hope that these pages may raise the veil 
 for many exposing to their view at once a picture of 
 the Great Master, and of the scientific machinery 
 which he knew so well how to set in motion and how 
 to control. 
 
 In the execution of this attempt, we have to 
 acknowledge the great assistance we have received 
 
VI PREFACE. 
 
 from the admirable works of M. Vallery-Radot 
 (" Histoire d'un Savant par im Ignorant "), and of 
 M. Diiclaux (" Histoire d'lm Esprit"), as well as from 
 the concise and artistic notice, entitled " L'CEuvre 
 Medicale de Pasteur," given by M. Roux in the 
 "Agenda du Chimiste" for 1896. 
 
 For the reproduction of the portraits we are 
 indebted to the courtesy of the family of the late 
 M. Pasteur. 
 
 P. F. F. 
 
 G. C. F. 
 
 Birmingham. 
 
TABLE OF CONTENTS. 
 
 Pkeface .......... 
 
 Chap. I. — Eakly Years 
 
 Chap. II. — Chemical Eesearches 
 Chap. III. — Fermentation Studies •• . 
 Chap. IV. — Discovery of Anaerobic Life . 
 Chap. Y. — Spontaneous Generation Controtersy . 
 Chap. YI. — Studies on the Yinegar Organism . 
 Chap. YII.— The Diseases of Wine .... 
 Chap. YIIT.— Eesearches on Silkworm Diseases . 
 Chap. IX. — Studies on Beer ..... 
 Chap. X. — Introduction to the Study of Infectious 
 
 Diseases 
 
 Chap. XI. — Eesearches on Anthrax 
 
 Chap. XII. — First Eesearches in the Domain of Immunity 
 Chap. XIII. — Discotery of Anthrax Yaccine 
 
 Chap. XIY. — Eabies 
 
 Chap. XY. — The Institut Pasteur 
 
 Chap. XYI. — Closing Years 
 
 page 
 
 V 
 
 9 
 26 
 34 
 45 
 53 
 67 
 77 
 83 
 108 
 
 123 
 130 
 
 149 
 155 
 164 
 185 
 209 
 
PASTEUE. 
 
 CHAPTER I. 
 
 EAKLY YEARS. 
 
 In a poor quarter of Dole stands a little house 
 bearing the simple inscription in gold : — 
 
 "Ici EST N^ Louis Pasteur 
 LE 27 Decembre, 1822." 
 
 When an infant of but two years of age, Louis 
 Pasteur's parents removed to the town of Arbois, where 
 his childhood was passed, for here his father purchased 
 a small tannery. That this hard-working tanner was 
 a man of character and stern experience, is shown by 
 the fact that he had fought in the legions of the 
 First Empire, and that he had been decorated on the 
 field of battle by Napoleon ; but the rough soldier 
 had his heart in the right place, and the home at 
 Arbois appears to have been one of those establish- 
 ments which revolve round the children, and the 
 greatest sacrifices were made by the parents to secure 
 the best educational advantages for the son. Nor 
 was Pasteur unmindful of this unselfish devotion in 
 after years, for the most celebrated ot" his works bears 
 the dedication : — 
 
10 PASTEUR. 
 
 " A la Memoire de man Pere, ancien militawe sous le Premier 
 
 Empire^ Chevalier de la Legion d^Honneur. 
 Plus fai avance en age, tnieux fai compris ton amitie et la 
 
 superiorite de ta 7'aiso?i. 
 Les efforts que fai consacre's a ces Etudes et a celles qui les ont 
 
 preced'ees sont le fruit de tes exemples tt de tes conseils. 
 Voidant honorer ces pieux souvenirs, je dedie cet ouvrage a ta 
 
 memoire" * 
 
 a tribute surely more imperishable and more covet- 
 able even than the ribbon pinned to his tunic by the 
 victor of Marengo and Austerlitz ! 
 
 When old enough, Pasteur was sent as a day scholar 
 to the College Communal ; but books and study had 
 little attraction for him, and he preferred to follow 
 his favourite pastime of fishing, and to delight his 
 companions and neighbours by sketching their por- 
 traits, some dozen of which are still shown with pride 
 by the inhabitants of Arbois. 
 
 "What a pity he has buried himself amongst a 
 heap of chemistry!" remarked an old woman of Arbois 
 many years later. " He has missed his vocation, for 
 he would some day have really succeeded in making 
 a name as a painter ; " and, indeed, the portrait of his 
 mother which used to hang in his house in Paris 
 is in itself evidence of the marked artistic talent 
 possessed by Pasteur when a mere lad. 
 
 But as time went on, young Pasteur began to 
 reaUse the sacrifices his parents had made for his 
 education ; and rousing himself from his lethargy, 
 he put from him his hobby and his pastime, locked 
 away his brushes and his fishing-tackle, so as to be 
 delivered from temptation, and put his shoulder to 
 
 * " Etudes sur la Biere." rublislied in 1876. 
 
EARLY YEARS. 11 
 
 the wheel. From that day onwards Pasteur may be 
 said to have hardly ever paused in the pursuit of 
 those Herculean labours, which his genius throughout 
 his life supplied in such rapid succession for his in- 
 domitable energy to perform. 
 
 The college of Arbois having at this time no pro- 
 fessor of philosophy, Pasteur left for Besanr;on, where 
 at the end of the academic year he took his degree of 
 bachelier es lettres, and was at once appointed "maitre 
 repetiteur," or tutor, in the college. The fond ambi- 
 tion and hope of his father at this time was often 
 repeated, " Ah ! si tu pouvais devenir un jour pro- 
 fesseur, et professeur au college d' Arbois, je serais 
 I'homme le plus heureux de la terre." But fathers are 
 not generally the best judges of the capacity of their 
 offspring, and this was certainly far too modest an 
 estimate of young Pasteur's powers ; for even in those 
 early days his old schoolmaster, watching his Avork 
 and progress, exclaimed, " Ce n'est pas vers la chaire 
 d'un petit college comme le notre qu'il faut le diriger, 
 il faut qu'il soit professeur dans un college royal. 
 . . . Mon petit ami, pensez a la grande Ecole 
 Normale ! " 
 
 Perhaps this encouraged Pasteur to attend special 
 courses of instruction in mathematics in the time 
 which he could spare from his other studies, so as 
 to prepare himself for the examination in science of 
 the Ecole Normale of Paris. It was at this time also 
 that his special interest in chemistry began to show 
 itself, and the eager questions with which he plied 
 and embarrassed the venerable professor Darlay before 
 his class, were such that the latter was at length re- 
 duced to telling his pupil that it was for him to 
 
12 PASTEUR. 
 
 interrogate Pasteur and not for Pasteur to submit him 
 to a cross-examination before all his scholars. Pasteur 
 was compelled to restrain his enthusiasm in the class- 
 room, but he hunted out a pharmaceutical chemist 
 in the town, who had acquired some local celebrity 
 through being the author of a paper which had 
 been deemed worthy of publication in the Annates 
 de Chmiie et de Physique, and him he persuaded to 
 secretly assist him in his studies. 
 
 Pasteur subsequently presented himself for the 
 entrance examination of the Ecole Norm ale. An inci- 
 dent attended his entry as a student which is worth 
 recording as indicative of his extraordinary persever- 
 ance, and of the exacting standard of performance 
 which he imposed upon himself Although he passed 
 and was admitted, he only obtained the fourteenth 
 place. This position did not satisfy him, and he 
 determined to withdraw and work for another year, 
 and then go in for the examination a second time. 
 For this purpose he went to Paris to study, and the 
 following year, in October, 1843, on again submitting 
 to the examination, he gained the fourth place. 
 
 Pasteur's love for chemistry had now developed 
 into a passion, and with Dumas at the Sorbonne, and 
 Balard at the Ecole Norm ale, he had every oppor- 
 tunity for gratifying his taste, for the students 
 attended both courses of lectures. In each of these 
 great masters of chemical science the young Pasteur 
 was impressed by what was most admirable, by the 
 great grasp of well-digested facts and details possessed 
 by the discoverer of bromine, by the lofty generalisa- 
 tions indulged in by the author of the theory of types. 
 It was at this time, too, that the foundations were 
 
EARLY YE Alls. 13 
 
 laid of that strict habit of mind which led him to 
 avoid all hypotheses, however seductive, which were 
 not supported on a sound basis of experimental facts 
 defying refutation : an attitude of mind which many 
 years later found expression in the address to his 
 colleagues at the public inauguration of the Institut 
 Pasteur * : — 
 
 "For the investigator it is the hardest ordeal which he 
 can be asked to face — to believe that he has discovered a 
 great scientific truth, to be possessed with a feverish desire 
 to make it known, and yet to impose silence on himself for 
 days, for weeks, sometimes for years, \Yhilst striving to destroy 
 these very conclusions, and only permitting himself to pro- 
 claim his discovery when all the adverse hypotheses have been 
 exhausted." 
 
 As a student, Pasteur's energy and enthusiasm 
 were boundless. Not even on Sundays did he rest 
 from his chemical studies ; and some idea may be 
 formed of his industry by the fact that on one of 
 these days of rest he actually succeeded m the diffi- 
 cult task of preparing no less than sixty grammes of 
 phosphorus from bones which he had bought at a 
 butcher's, an operation which lasted from four in the 
 morninof to nine o'clock at nisfht. 
 
 It is doubtless the experience of many who have 
 attended great seats of learning that, much as may be 
 the indebtedness to professors, the real fire of research 
 is not unfrequeutly kindled by the fertile suggestions 
 of junior men with w^hom students can associate on 
 more equal terms ; and whatever Pasteur may have 
 owed to Dumas and Balard, there can be no doubt 
 that he was helped on to the first rung of the ladder 
 
 * See p. 186. 
 
14 PASTEUR. 
 
 which he scaled with such dexterity and success, by 
 a man of this kind. It was Delafosse, a former 
 pupil and assistant of the renowned Haiiy, who 
 turned Pasteur's attention to the study of crystals 
 and to problems of molecular physics, in which 
 domain his first laurels were won. 
 
 In order to appreciate the importance of the part 
 played by Pasteur in the particular field of research 
 to which he first devoted his attention, a few words 
 of introduction are necessary to indicate the stage 
 at which the inquiry had arrived, when Pasteur and 
 Delafosse were so eagerly discussing together in- 
 tricate problems on the arrangement of molecules. 
 
 The phenomena of double refraction were already 
 known to Huygens and Newton, but the subtle differ- 
 ence between the nature of the light composing the 
 ordinary and extraordinary rays respectively was not 
 understood until Mains made the far-reaching dis- 
 covery in 1808 of the polarisation of light by re- 
 flection, and subsequently showed that the rays 
 which are transmitted through Iceland spar differ 
 from those of ordinary light in being polarised. 
 
 The wonderful and intricate phenomena of polari- 
 sation, which form such an attractive chapter in ex- 
 perimental optics, were investigated after the untimely 
 death of Mains in 1812 by Arago, and more especially 
 by Biot, who practically devoted his whole life to this 
 study. It is almost impossible to over-estimate the 
 debt which chemical science owes to the patient re- 
 searches of this physicist ; for in the course of his 
 labours, he made in 1815 the discovery that there 
 are a number of natural organic substances — such as 
 sugar, camphor, tartaric acid, oil of turpentine, etc. — 
 
PASTEUR WHEN A STUDENT AT THE ECOLE NORMALE. 
 
 [To face jmgc If 
 
EARLY YEARS. 15 
 
 which possess the remarkable property of rotating the 
 plane of polarisation when a beam of polarised light is 
 passed through them either in the liquid or dissolved 
 state. Nor was Biot slow in perceiving the enormous 
 theoretical importance of this discovery ; for he at 
 once pointed out that whereas in the previously- 
 known phenomena of the rotation of the plane of 
 polarisation by crystals — e.g. quartz — the rotation is 
 conditioned by the crystalline form, disappearing alto- 
 gether as it does so soon as that form is destroyed, 
 in the case of these organic substances this rotatory 
 power must be inherent in the molecules themselves ; 
 for being exhibited by liquids, it must be dependent 
 upon the one structure which still remains — the 
 molecule itself. 
 
 This discovery of Biot's had thus placed the 
 physical phenomena of polarisation on the doorstep 
 of the chemist, and we shall soon see how the latter 
 availed himself of this legacy. 
 
 It was in 1844, when Pasteur was still a student 
 at the Ecole Normale, that Biot communicated to 
 the Academy of Sciences a note by the German 
 chemist, Mitscherhch, and it was this memoir which 
 finally, as it were, set the ball rolling, and started 
 Pasteur on that voyage of discovery which was 
 coextensive with his life. 
 
 Mitscherlich had discovered that the two tartaric 
 acids so familiar to chemists, while apparently identi- 
 cal in chemical composition, in chemical properties, 
 in crystalline form, and, in fact, in every known 
 detail, behaved differently in solution towards polar- 
 ised light, the solution of the one turning the plane 
 of polarisation to the right, whilst the solution of the 
 
16 PASTEUR. 
 
 Other (general^ called paratartaric or racemic acid) 
 produced no effect whatever on the polarised beam. 
 At the close of his memoir Mitscherlich adds, " The 
 nature and number of atoms in these two bodies, as 
 well as their arrangement and the distances between 
 them, are identical." 
 
 " How," reflected Pasteur, " can we accept the 
 identity in the nature and number of atoms, admit 
 that the relative distance and arrangement and the 
 crystalline form are the same in these two bodies, 
 without admitting also their absolute and entire 
 identity throughout ? A profound incompatibility 
 surely exists between Mitscherlich's discovery of the 
 different relationship of these two tartrates towards 
 polarised light, and his statements that they are 
 identical in every particular." This problem haunted 
 Pasteur continually, and his attention was now wholly 
 devoted to the study of crystals, the determination of 
 their angles and their form, when he heard with dis- 
 may that he had been nominated Professor of Physics 
 at the Lycee of Tournon. Fortunately, however, 
 through the intervention of Balard, to whom he 
 was now acting as assistant, this threatened inter- 
 ruption to his work was avoided; the appointment was 
 cancelled, and Pasteur was permitted to remain at 
 the laboratory of the Ecole Normale. 
 
 In order to train himself yet more perfectly in the 
 examination of crystals, Pasteur determined to repeat 
 an elaborate piece of work which the celebrated crys- 
 tallographer, Do la Provostaye, had published on 
 tartaric and paratartaric acids and their salts. 
 
 Many years later Pasteur refers with enthusiasm 
 to the keen pleasure he experienced at this time in 
 
EARLY YEARS. 17 
 
 producing the crystals of tartaric acid and its deri- 
 vatives " Dont les cristaux," he said, " rivahsent en 
 dimension et en beaute avec les plus belles formes 
 cristallines connues." 
 
 It was soon evident, however, that mere repetition 
 and confirmation was not Pasteur's strong point ; for 
 although a comparative novice at the kind of work in 
 question, he was able to see what had escaped the ob- 
 servation of his skilled predecessor in this field, and to 
 detect a minute point of difference which had eluded 
 the vigilance of the most accomplished crystallo- 
 graphers of the day — Mitscherlich and Biot, as well as 
 Provostaye. On the crystals of the tartrate which 
 was active to polarised light Pasteur found some 
 minute faces which were absent from the crystals of 
 the tartrate inactive to the polarised beam. Such 
 importance did he at once attribute to these little 
 faces, that he recognised that their presence relegated 
 the substance possessing them to an entirely different 
 class of objects from that to which belonged the sub- 
 stance in which they were absent. 
 
 The presence of such faces on crystals of quartz 
 had not escaped the attention of Haiiy, who, indeed, 
 had further divided such quartz crystals into left and 
 right-handed quartz, according to the side on which 
 these faces were developed. Pasteur, intimately ac- 
 quainted with the work and speculations of Haiiy and 
 others, had been profoundly impressed with the re- 
 markable relations which subsequent experiments had 
 proved existed between the power to turn the plane 
 of polarisation, and the presence of these faces on 
 quartz crystals. It was in consequence of his being so 
 deeply imbued with the idea that polarimetric effect 
 
 B 
 
18 PASTEUR. 
 
 must be associated with crystalline form, that the ap- 
 pearance of these little faces on some of the tartrate 
 crystals and their absence on others seemed to him of 
 the very highest importance, and deserving of the 
 most careful study. 
 
 Pursuing, therefore, his minute examinations of 
 these crystals, he found that whilst the crystals of the 
 inactive tartaric acid which were destitute of these 
 little surfaces were symmetrical, the crystals of the 
 optically active tartaric acid were unsymmetrical, or 
 dissymmetric, as he called it. Now, to the symmetric 
 character of the crystals of the one tartaric acid, 
 generally known as para tartaric or racemic acid, he 
 attributed the inactivity of this tartaric acid to 
 polarised light, whilst with the dissymmetric char- 
 acter of the crystals of the other tartaric acid he 
 connected its action on the polarised beam. 
 
 The intrinsic and fundamental difference between 
 these two classes of bodies — the symm^etric and the 
 dissyr}i7)ietric — is perhaps most easily realised by 
 placing them before a mirror, when in the case of the 
 symmetric body the image will be identical with the 
 object, whilst in the case of the dissymmetric body 
 the image and object are not identical, but bear the 
 same relationship to each other as the left and right 
 hands do, which are perhaps the most familiar in- 
 stances of dissymmetric objects. Thus placing the 
 crystal ot active tartaric acid in front of a mirror, the 
 reflection obtained is not identically the same crystal 
 as the original, but related to it as the left hand to the 
 right hand ; but on placing the crystal of the inactive 
 tartaric acid before a mirror, the image is in every 
 respect identical with the original crystal. 
 
EARLY YEARS. 19 
 
 In studying these apparently insignificant details, 
 Pasteur found that by crystallising the inactive tartaric 
 acid (paratartaric or raceniic acid) in a particular 
 way,* he obtained two different kinds of crystals — the 
 one set being identical with those of the active tartaric 
 acid already known, whilst the other set were the 
 mirror images of these, and had never been seen by 
 the eye of man before. The young philosopher at 
 once drew the conclusion that if the dissymmetry of 
 the known tartaric acid caused it to turn the plane of 
 polarisation to the right, the dissymmetry of this new 
 tartaric acid would turn it to the left. 
 
 With infinite pains Pasteur picks out from the 
 mixture the individual crystals belonging to each 
 of the two types, and arranges them in two heaps. 
 Each of these heaps of crystals was then separately 
 dissolved in water, and the two solutions submitted 
 to polarised light. In accordance with his antici- 
 pation, whilst the solution of the crystals of the 
 known form was found to turn the plane of polarisa- 
 tion to the right, the solution of the new crystals, 
 the mirror-images of the old, was found to turn the 
 plane through precisely the same angle to the left. 
 
 This might have appeared to many a trivial dis- 
 covery only; but such was not Pasteur's opinion of 
 it, for rushing from the laboratory in a fever of ex- 
 citement, and meeting Bertrand in the corridor, he 
 embraced him, exclaiming, overcome with emotion, 
 " Je viens de faire une grande decouverte ! J'ai separe 
 le paratartrate double de sonde et d'ammoniaque en 
 deux sels de dissymetrie inverse et d'action inverse 
 sur le plan de polarisation de la lumiere. Le sel droit 
 
 * By preparing- the sodium ammonium salt and crystallising this. 
 B 2 
 
20 PASTEUR. 
 
 est de tout point identique au tartrate droit. J'en 
 suis si heureux que j'eprouve un tremblement ner- 
 veux qui m'empeche de remettre de nouveau I'oeil 
 a I'appareil de polarisation. Aliens au Luxembourg ; 
 je vous expliquerai tout cela ! " 
 
 As might have been anticipated, this discovery 
 made by a young man but twenty-five years of age, 
 his first venture in the scientific arena, and challeng- 
 ing the opinions and statements of such world-famed 
 veterans as Biot, Mitscherlich, and Provostaye, whilst 
 producing a great sensation in scientific circles, Avas 
 received with no little scepticism by the Academy 
 of Sciences. 
 
 We are, moreover, quite familiar with remarkable 
 results obtained by mature and well-seasoned in- 
 vestigators being received with incredulity or reserve, 
 as it is euphemistically called, and it is not surprising, 
 therefore, that such a striking discovery made by a 
 young and almost unknown man should have been 
 accepted with considerable hesitation. The duty of 
 reporting on this paper was entrusted to the highest 
 living authority on such a subject, to Biot himself, 
 and we are tempted to give Pasteur's own account 
 of the extraordinarily stringent investigation to which 
 the half-sceptical veteran submitted the young man's 
 almost suspiciously plausible results : — 
 
 " He [M. Biot] sent for me to repeat before his 
 eyes the several experiments. He gave me racemic 
 acid which he had himself previously examined and 
 found to be quite inactive to polarised light. I pre- 
 pared from it in his presence the sodium ammonium 
 double salt, for which he also desired himself to pro- 
 vide the soda and ammonia. The liquid was set aside 
 
EARLY YEARS. 21 
 
 for slow evaporation in one of the rooms of his own 
 laboratory, and Avhen 30-40 grms. of crystals had 
 separated he again summoned me to the College de 
 France, so that I might collect the dextro- and Isevo- 
 rotatory crystals before his eyes, and separate them 
 according to their crystallographic character, asking 
 me to repeat the statement that the crystals which I 
 should place on his right hand would cause deviation 
 to the right, and the others to the left. This done, 
 he said that he himself would do the rest. He pre- 
 pared the carefully weighed solutions, and, at the 
 moment when he was about to examine them in the 
 polarimeter, he again called me into his laboratory. 
 He first put the more interesting solution, which 
 was to cause rotation to the left, into the apparatus. 
 Without making a reading, but already at the first 
 sight of the colour- tints presented by the two halves 
 of the field in the Soleil saccharimeter, he recognised 
 that there Avas a strong la3vo-rotation. Then the 
 illustrious old man, who was visibly moved, seized me 
 by the hand, and said, ' Mon cher enfant, j'ai tant 
 aime les sciences dans ma vie que cela me fait battre 
 le coeur ! ' " 
 
 For more than thirty years Biot, who was the 
 first to discover the behaviour of organic chemical 
 substances towards polarised light, had urged that 
 the polarimetric study of these substances might 
 possibly prove an important avenue to the under- 
 standing of their constitution ; but although he had 
 led scientific thought, and directed experimental 
 activity with marvellous instinct in the direction of 
 that new realm of chemistry, so fraught with fascina- 
 ting and absorbing interest to the investigator, it was 
 
22 PASTEUR. 
 
 not given to Biot himself to cross the frontier, but 
 this advance was reserved for Pasteur. 
 
 Thus Pasteur pointed out that the differences in 
 optical properties and in crystalline form exhibited by 
 these two oppositely active tartaric acids were doubt- 
 less dependent on the two molecules having a different 
 arrangement of their constituent atoms, the arrange- 
 ment in each case being dissymmetric, and clearly 
 indicated that whatever the dissymmetry of the one 
 tartaric acid might consist in, it must be related to 
 the dissymmetry of the other tartaric acid in the 
 same sort of way as the dissymmetry of the left hand 
 is related to the dissynnnetry of the right hand ; still, 
 at the time, organic chemistry was not sufficiently ad- 
 vanced to make any immediate use of these specula- 
 tions. The remarkable progress and development of 
 organic chemistry which characterise the latter half of 
 the present century before long led to the further 
 interpretation of these phenomena exhibited by the 
 tartaric acids. For some years later (1869) Wislicenus 
 was confronted with similar phenomena in the case of 
 lactic acid ; and with the more perfect knowledge 
 which had then been gained as to the grouping of the 
 atoms in the molecule, he was led to hazard the sug- 
 gestion that the difference between the two lactic acids 
 was due to a difference in the arrangement of the 
 atoms in the molecule which could not be represented 
 by the ordinar}^ plane formula3 of chemists, but re- 
 quired a consideration of the arrangement of the 
 atoms in the three dimensions of space. 
 
 This suggestion, giving as it did further substance 
 to Pasteur's previously expressed views of dissymmetry, 
 was the foundation of that most fascinating and fertile 
 
EARLY YEARS. 23 
 
 field of chemical science which is now known as 
 stereo-chemistry, the guiding principles of which were 
 elaborated in 1874 with such rare skill and prescience 
 by Yan't Hoff' and Le Bel, and which, like nearly all 
 new and original departures in science, met at the 
 outset with the most scathing criticism and even 
 scornful ridicule from some of the conservative pro- 
 fessors of the time. 
 
 These views concerning the spacial arrangement of 
 the atoms within the molecule have, however, long 
 since passed their probationary stage, and their pro- 
 visional acceptance at any rate has become absolutely 
 indispensable to a proper understanding of recent 
 advances in our knowledge of the carbon compounds. 
 The fertility of these views in stimulating successful 
 researches has been almost limitless. Thus, some of 
 the most brilliant achievements of modern chemists, 
 such as the artificial synthesis by Ladenburg of the 
 alkaloidal poison Coniine, which forms the deadly 
 instrument of execution concealed in the cup of hem- 
 lock, and the wonderful series ot investigations which, 
 in the able hands of Emil Fischer, has culminated in 
 the preparation of some of the principal natural sugars : 
 these investigations owe their success entirely to the 
 guidance of those theories of stereo-chemistry which 
 are the direct outcome of Pasteur's fundamental re- 
 searches on the tartaric acids. 
 
 The theory of the arrangement of the atoms in 
 space has, however, also been applied with great 
 success to substances which have no action on 
 polarised light at all. Amongst the enormous 
 number of carbon compounds prepared and accu- 
 rately studied during the past fifty years, it has 
 
24 PASTEUR. 
 
 repeatedly been found necessary to assume that in 
 some the atoms are arranged in a -closed chain or 
 ring, as 023posed to the open chain arrangement which 
 must be assumed to exist in many others. Now one 
 of the most striking things about these closed chains 
 is the fact that they almost invariably consist of either 
 five or six atoms ; a vast number of these ring com- 
 pounds are, in fact, derivatives of the well-known 
 hydrocarbon benzene, in which chemists have long 
 recognised the presence of a ring consisting of six 
 atoms of carbon. This remarkable predisposition 
 to form five- or six- atom rings finds a ready expla- 
 nation when Van't HofF's views with regard to the 
 relative positions of the atoms in space are taken 
 into consideration. 
 
 The fertility of these speculations has led to 
 chemists constructing similar hypotheses with regard 
 to the arrangement in space of the groups attached to 
 nitrogen atoms, the investigation of which is being 
 eagerly prosecuted by numerous workers at the pre- 
 sent time, whilst others still more imaginative are 
 extending stereo-chemical views even to some of the 
 compounds of platinum, cobalt, and other metals. 
 
 By these first researches we see, then, that Pasteur 
 became the father of one of the most wonderful de- 
 partments of modern chemistry — namely, the one 
 which has for its ambition the discovery of the 
 spacial distribution of the individual atoms in the 
 molecule. Thus, Pasteur's first researches possessed 
 in themselves purely theoretical interest ; they were, 
 however, masterpieces of thoroughness, and exhibited 
 so much experimental skill, intuition, and power of 
 careful observation, combined with clear judgment, 
 
EARLY YEARS. 25 
 
 that, even had his career been cut short at this stage, 
 we should have had no hesitation in recognising in 
 him one of the most remarkable and exceptionally 
 gifted of investigators. 
 
 From these early researches, however, we should 
 have had no positive indication of the man's power 
 of harnessing science to the problems of practical 
 life. But his genius was not long to be retained 
 in the exclusive service of abstract science, and it 
 is interesting to follow the circumstances which 
 led him to find scope for the practical side of 
 his abilities. It was not, as many might suppose, 
 that he had suddenly set himself some definite 
 problem of great practical moment to work out, 
 for in scientific investigation it almost invariably 
 happens that one step leads to another : the ex- 
 perience gained in one piece of work qualifies the 
 worker to follow on in some definite direction and 
 not to plunge into the unknown at random. Thus 
 in Pasteur's case the great practical work of his life 
 followed almost as a necessary consequence, on his 
 achievements in the purely scientitic domain to which 
 we have already referred. 
 
CHAPTER II. 
 
 CHEMICAL RESEARCHES. 
 
 Pasteur's academic career was now assured, and 
 already, at the end of the year 1S48, he Avas appomted 
 Professor of Physics at the Lycee of Dijon, and 
 three months later he was nominated deputy pro- 
 fessor of chemistry at the University of Strassburg, 
 becoming full professor in 1852. 
 
 This translation to Strassburg, quite apart from 
 its importance in giving Pasteur greater scope for 
 the pursuit of his scientific work, was to acquire 
 for him a profound personal significance, for here 
 he met his future wife, the daughter of M. Laurent, 
 Rector of the Strassburg Academy. Their marriage, 
 which took place in 1850, proved a singularly happy 
 one, and it is impossible to rightly appreciate 
 Pasteur's life without some understanding of the im- 
 mense assistance which he received in his own home. 
 Whether in discussing forms of crystals, watching 
 over experiments, shielding her husband from all 
 the daily fret of life, or busy at the customary 
 evening task of writing to his dictation, Madame 
 Pasteur was at once his most devoted- assistant 
 and incomparable companion. His surroundings at 
 home were entirely subordinated to his scientific 
 life, and his family shared with him both his trials 
 and his triumphs. At the time when Pasteur 
 
CHEMICAL RESEARCHES. 27 
 
 was engrossed with the study of anthrax, and after 
 many difficuhies and disappointments had at length 
 succeeded in preparing a vaccine against anthrax, 
 he at once hurried from the laboratory to com- 
 municate his great discovery first to his wife and 
 daughter ; and this is but an instance of the bond of 
 sympathy which was maintained throughout his life 
 between the great savant and those around him. 
 
 Pasteur had an extraordinary power of concentrat- 
 ing his attention upon a single subject, and perhaps 
 the most important part of his work was done in those 
 hours when he would sit silent and immovable, deep 
 in thought, occupied with some difficult problem, 
 allowing nothing to disturb or distract him until he 
 had found some solution.. But when he had dis- 
 covered a key to the difficulty the whole ex- 
 pression of his face would alter ; he would become 
 radiant with delight, and eagerly communicate to 
 those around the experiments he had planned and 
 the hopes of success which he cherished. The 
 sympathy which throughout his life he sought so 
 constantly, Avh ether in his troubles or triumphs, 
 was never failing, and the loving support he 
 received at all times helped him in after years to 
 sustain those great physical trials which fell so 
 heavily upon him, and which he endured with such 
 patience. 
 
 During the five years he resided in Alsace, 
 Pasteur devoted himself almost exclusively to the 
 systematic investigation of asymmetric compounds ; 
 and with this period of his life are associated those 
 important and now classical researches on the con- 
 version of rio^ht-handed tartaric acid into inactive 
 
28 PASTEUR. 
 
 tartaric acid (racemic acid) on the one hand, and 
 into a new form of inactive tartaric acid (mesotartaric 
 acid) on the other ; his discovery of the method of 
 sphtting up racemic acid into its component dextro- 
 and kevo-tartaric acids by means of ojotically active 
 bases ; and his famous refutation of Dessaignes' 
 reputed conversion of fumaric and maleic acids 
 into aspartic acid, identical with that hitherto only 
 obtamed from asparagine. 
 
 Pasteur had himself studied these various bodies 
 before the publication of Dessaignes' memoir, and 
 had found that whilst fumaric and maleic acids 
 were not dissymmetrical — that is to say, were 
 destitute of all optical activity, had no effect on 
 polarised light — aspartic acid, like asparagine, from 
 which it is derived, was endowed with molecular 
 dissymmetry and was active towards polarised light. 
 
 If Dessaignes' facts were correct they woidd 
 mean that he had accomplished what Pasteur firmly 
 believed to be unrealisable — the preparation by 
 artificial chemical means of an optically active 
 molecule from an inactive one. Of such pressing 
 importance did the settlement of this doubt appear 
 to Pasteur that he at once, with his usual restless 
 energy, set off for Vendome and obtained from 
 Dessaignes a specimen of his artificial aspartic 
 acid. On returning to his laboratory, Pasteur ex- 
 amined it with the minutest care, and found that in 
 spite of its great resemblance to the acid derived from 
 asparagine, it differed from it in a very important 
 particular, inasmuch as it was entirely devoid of 
 the action on polarised light which characterised the 
 latter, and he had no difficulty in showing that 
 
CHEMICAL RESEARCHES. 29 
 
 Dessaignes' acid was not identical with tlie natural 
 aspartic acid, but only a so-called inactive isomeride. 
 
 The dogma set up and so obstinately clung to by 
 Pasteur, that asymmetric bodies cannot be artificially 
 prepared, led him into some abstruse speculations 
 concerning their production in nature, which have 
 hitherto only received negative illumination from 
 direct experiment. He points out that it is neces- 
 sary and quite sufficient to suppose that at the 
 genesis of a vegetable organism some asymmetric 
 force must be in operation, and suggests that light, 
 electricity, magnetism, and heat may be subject to 
 asymmetric influences of a cosmic nature. Are 
 these, he asks, perhaps connected with the motion of 
 the earth, or with those electric currents by means of 
 which physicists explain the magnetic poles of the 
 earth ? At any rate, these asymmetric forces are 
 wanting in our synthetical reactions, or are without 
 influence on them, possibly in consequence of their 
 rapid course. 
 
 Nor did Pasteur simply propound these questions, 
 but on the contrary the great master of the experi- 
 mental method undertook a bold campaign into this 
 highly speculative domain, from which, however, he 
 soon deemed it more prudent to retreat: doubtless 
 realising that his intellectual forces might be more 
 advantageously employed in other directions than in 
 a territory where only negative victories were to be 
 won. Thus at Strassburg he actually had powerful 
 magnets constructed with a view to introducing dis- 
 symmetric influences during the formation of crystals. 
 At Lille, again, in 1854, he had a clockwork arrange- 
 ment made with which he intended by means of a 
 
30 PASTEUR. 
 
 heliostat and reflector to reverse the natural move- 
 ment of the solar rays striking a plant from its cradle 
 to the ofrave, so as to see whether in such an artificial 
 world, in which the sun rose in the west and set in the 
 east, the optically active bodies would not appear in 
 the opposite forms to those which the existing order 
 of nature provides. 
 
 Pasteur, however, soon realised, doubtless in- 
 structed by his experience gained in other voyages 
 of discovery on which he shortly embarked, that the 
 task of turning the Creator's universe upside down 
 was even beyond his experimental skill ; recognising 
 that, however he might reverse these external in- 
 fluences, he would still have to deal with the 
 asymmetric agencies already present with all 
 their irresistible albeit latent power in the germ 
 of life itself, and that without the possibility of spon- 
 taneous generation there was also no possibility of 
 realising this dream of a new world with its plants 
 and animals producing the optical antipodes of 
 the natural celluloses, albumens, starches, sugars, 
 terpenes, etc., for the edification of the young 
 stereo-chemical philosopher. 
 
 So far Pasteur had kept strictly to the domain of 
 pure chemistry and molecular physics, and his atten- 
 tion was entirely absorbed by problems which, while 
 of profound theoretical interest, gave no indication 
 of the direction which his future labours would 
 take, and to the pursuit of which his whole life was 
 subsequently to be devoted. 
 
 Hardly realising it, however, Pasteur drifted away 
 from his original anchorage, as it were, and while 
 still eagerly pursuing the fascinating occupation of 
 
CHEMICAL RESEARCHES. 31 
 
 searching out physico-chemical problems, he found 
 himself confronted and hemmed in by questions and 
 problems of an entirely different order, and awoke 
 to find that he had passed out of the comparatively 
 quiet reaches of abstract science into the troubled 
 waters of science in its relation to practical life. 
 
 It was an incident trifling in itself which first 
 suggested to Pasteur the application of fermentation 
 processes to the study of chemical substances, and 
 which subsequently led him to devote the whole of 
 his energies to the study of biological phenomena. 
 A German firm of manufacturing chemists had ob- 
 served that if solutions of impure commercial tartrate 
 of lime were left in warm weather in contact with 
 organic matters, they fermented and gave rise to 
 various products. 
 
 Pasteur, to whom no phenomenon was trifling or 
 insignificant, at once conceived the idea of utilising 
 this fact by inducing, in the first instance, fermentation 
 in a solution of ordinary right-handed tartaric acid. 
 For this purpose he dissolved a salt of this acid, and 
 added to its solution a small quantity of albumen. 
 Fermentation followed, and the liquid, originally clear, 
 became gradually turbid, a phenomenon which Pasteur 
 found was due to the presence of small living cells, 
 upon which he subsequently showed the process of 
 fermentation to be dependent. This method he also 
 applied to solutions of the paratartrate (racemate), 
 with the same results. On examining these solu- 
 tions after fermentation with the polarimeter, the 
 most profound difference was, however, found to exist 
 between them. 
 
 In the case of the paratartrate (racemate) the 
 
32 PASTEUR. 
 
 liquid, originally inactive, exhibited as the fermenta- 
 tion proceeded a gradually stronger and stronger 
 deviation of the plane of polarisation to the left, until 
 the maximum was reached and the fermentation 
 ceased. It was then found that during the process 
 of fermentation the right-handed acid had been con- 
 sumed, leaving the left-handed acid alone master of 
 the field ; and the latter, thus freed from the con- 
 straining influence of its right-handed brother, was 
 able to assert itself and exhibit for the first time 
 its left-handed rotatory power. 
 
 In plain language this means that, whilst right- 
 handed and left-handed tartaric acids are chemically 
 identical, and are distinguishable only by their crystal- 
 line form and opposite action on polarised light, they 
 are, nevertheless, utterly different from a physiological 
 point of view ; for the right-handed tartaric acid is 
 alone taken up and transformed by the fermentative 
 bacteria, which refuse to have anj^thing to do with the 
 left-handed tartaric acid. Thus the apparently trivial 
 difference in the arrangement of the atoms in space in 
 the case of these two tartaric acids, makes an over- 
 whelming difference in their physiological character. 
 This phenomenon, which is undoubtedly one of the 
 most striking in the whole domain of chemical science, 
 appears to be a very general one in the case of bodies 
 admitting of two or more different arrangements of 
 their atoms in space. Although not further pursued 
 by its discoverer, this physiological difference has 
 been largely utilised by subsequent investigators for 
 the preparation of optically active compounds. 
 
 A couple of years later, in 1856, our Royal So- 
 ciety conferred the Rumford Medal upon Pasteur in 
 
CHEMICAL RESEARCHES. 33 
 
 recognition of his researches on the polarisation of 
 Hght with hemihedrism of crystals. 
 
 This, in briefest outline, is the work of Pasteur in 
 the domain of pure chemistry and molecular physics ; 
 as an example of the combination of rare experimental 
 skill and precision with consummate deductive power, 
 it stands out as one of the most remarkable and 
 artistic monuments in the annals of chemical science. 
 This work, begun, continued, and ended Avithin the 
 short period of ten years, is an achievement on which 
 an investigator might look back with pride at the 
 close of a life-time, and yet on its completion Pasteur 
 stood but on the threshold of his great career. 
 
 c 
 
CHAPTER III. 
 
 FERMENTATION STUDIES. 
 
 A NEW chapter in Pasteur's life opens with the year 
 18o4, when, at the age of thirty- two, he was nominated 
 the first Dean of the Faculty of Sciences, which had 
 just been created in the industrial centre of Lille. 
 
 As dean or principal of this new institution at 
 Lille, Pasteur at once realised that its Avork should, to 
 some extent, be brought in touch with one of the 
 leading industries of the district — the manufacture of 
 alcohol from beetroot and grain — and he therefore 
 determined to offer courses of lectures on fermentation, 
 and threw himself wdth his characteristic energy into 
 the serious study of this subject. 
 
 Thus it Avas that, at a time Avhen Pasteur's mind 
 Avas absorbed Avith the possibilities AA^hich had just been 
 opened out to him of aj^proaching chemical problems 
 from an entirely novel point of a^Icav, and Avhilst hesi- 
 tating Avhether he should alloAv himself to be carried 
 aAvay by a more intimate study of these fermentation 
 processes, the choice Avas practically taken out of his 
 hands, and the accident of his remoA^al to Lille virtu- 
 ally decided what course his investigations should 
 take. 
 
 At this time fermentation processes Avere not 
 generally regarded as vital phenomena at all, for the 
 dominant opinion concerning them Avas that of Licbig, 
 
FERMENTATION STUDIES. 35 
 
 who viewed the classical transformation of sugar into 
 alcohol as a purely chemical process, depending not 
 upon the living yeast cells which the microscope 
 revealed, but upon the dead yeast undergoing ])ost- 
 onortem decomposition. In Liebig's own words : — 
 
 " Beer yeast, and, in general, all animal and 
 vegetable matters in putrefaction iuipart to other 
 bodies the state of decomposition in which they are 
 themselves. The movement which, by the disturbed 
 equilibrium, is impressed on their own elements, is 
 comnumicated also to the elements of bodies in 
 contact with them." 
 
 A few words of retrospect are necessary to show 
 how these views of Liebig had gained ascendanc}^ 
 Already in 177G, Spallanzani had shown that 
 putrescible liquids and organic materials in general 
 could be permanently protected from undergoing 
 fermentation and decomposition by being thoroughly 
 boiled and subsequently shielded from all access of 
 air. Indeed, the well-known method of preserving 
 the most varied food-stuffs, first turned to practical 
 account by the ingenuity of the cook and confectioner 
 Appert, and which has assumed such colossal dimen- 
 sions at the present time, Avas the outcome of Spallan- 
 zani's experiments. The results obtained by Spallan- 
 zani were explained by Gay-Lussac as due to the 
 exclusion of atmospheric oxygen from the substances 
 employed. Gay-Lussac Avas led to this conclusion by 
 an examination of Appert's contrivance for the pre- 
 servation of animal and vegetable substances, which 
 consisted in hermetically sealing them in vessels and 
 subsequently submitting them to a high temperature 
 in a water bath. He observed that a sample of grape- 
 c 2 
 
36 PASTEUR. 
 
 must which had been preserved by this means im- 
 aUered for a Avhole year entered into fermentation 
 after it had been transferred from one vessel to 
 another, and had thus, Gay-Lussac pointed out, come 
 in contact, although only momentarily, with atmo- 
 spheric oxygen. Gay-Lussac therefore argued that it 
 was the presence of oxygen which was responsible for 
 and essential to fermentation processes, and this view 
 was the generally accepted one during the next twenty 
 3^ears, until the vital theory of fermentation was again 
 revived by Cagniard-Latour in 1837. 
 
 This investigator showed that the yeast cells, al- 
 ready observed and described in the deposit formed 
 during fermentation by the famous Dutch investigator 
 Leeuwenhoeck, as far back as 1675, were independent 
 organisms multiplying by budding. Latour also sug- 
 gested that the life of these cells was intimately 
 associated with the process of fermentation. Follow- 
 ing close upon the publication of Cagniard-Latour's 
 work came the extensive and masterly researches of 
 Schwann. Looking back upon these investigations 
 to-day, it is difficult, so convincing do they appear to 
 us now, to realise how it was that twenty years later 
 Pasteur had to begfin as it were de novo to rescue the 
 vital theory of fermentation from extinction at the 
 hands of the greatest scientific men of the day, Helm- 
 holtz and Liebig. 
 
 Schwann showed that Gay-Lussac's theory of the 
 dependence of fermentation processes upon the access 
 of oxygen was untenable, for he proved that putrescible 
 substances could be preserved unchanged even if they 
 were brought in contact with air, as long as the latter 
 had been thoroughly heated first. He also showed that 
 
FERMENTATION STUDIES. 37 
 
 the alcoholic fermentation of sugar and the produc- 
 tion of yeast cells did not take place as long as boiled 
 grape-juice was only brought in contact with heated 
 air. These results suo-o-ested to Schwann that the 
 presence of organisms might play an important part 
 in these processes ; and he therefore proceeded to tr}' 
 and impede the alcoholic fermentation by the addition 
 of various presumably noxious substances, and he 
 found that whilst mix vomica, so poisonous to annuals, 
 produced no deleterious effect, the addition of arsenic 
 did interfere with the fermentation process, and he 
 therefore concluded that these organisms Avere of a 
 veo-etable rather than animal character. He moreover 
 confirmed Cao-niard-Latour's observation that the de- 
 posit produced during fermentation consisted of 
 budding je^st cells. Schwann went still further, and 
 showed that the fermentation commenced Avith the 
 appearance of these cells in the " must," and that with 
 their multiplication the fermentation progressed, 
 whilst with its cessation the growth of the foimer 
 stopped also. 
 
 In the face of all these facts which he had estab- 
 lished, Schwann felt justified in restating emphatically 
 the conviction already expressed by Latour, that there 
 existed an undeniable connection between alcoholic 
 fermentation and the growth of the j^east cells, and he 
 suo'O'ested that the latter utilised the suo-ar as their 
 food material, and the part which they could not 
 assimilate they separated out in the form of alcohol. 
 
 Schwann was, however, prevented from fulfilling 
 his promise of furnishing more extensive experimental 
 evidence in support of these preliminary investigations, 
 but shortly afterwards Turpin repeated these researches, 
 
38 PASTEUR. 
 
 and was really the first who definitely formulated 
 the vitalistic theories of fermentative and putrefactive 
 processes. 
 
 These conclusions were, however, far from being 
 generally accepted by the scientific authorities of the 
 day, and a few years later (in 1843) Helmholtz, at that 
 time a young medical student, made his first debut 
 before the scientific world in a paper which he pub- 
 lished on fermentation and decay. Helmholtz repeated 
 Schwann's experiments and confirmed his observations 
 that fermentation and putrefactive processes were sus- 
 pended, when the substances employed were boiled 
 and allowed only to come in contact with heated air, 
 thus again disproving the oxygen theory of fermenta- 
 tion brought forward by Gay-Lussac. But, said Helm- 
 holtz, if the admission of ordinary air to these boiled 
 substances induces fermentation and decay, then 
 either germs must be held responsible or else these 
 changes are due to the action of gaseous materials 
 present in the atmosphere, and which are destroyed by 
 heat. With the object of deciding this point he placed 
 boiled liquids in vessels covered with a bladder, argu- 
 ing that whereas no impediment was thus offered to 
 the passage of these diffusible gases, an insurmount- 
 able barrier was provided against the admission of 
 solid particles like germs. 
 
 A vessel containing boiled grape-juice was covered 
 with a bladder and immersed in another vessel con- 
 taining fermented " must," so that the two liquids were 
 only separated by the bladder. No fermentation Avas 
 subsequently set up in the boiled must, and this gave 
 support to the opinion that the process of lermenta- 
 tion was dependent upon the presence of germs. 
 
FERMENTATION STUDIES. 39 
 
 When, however, experiments carried out on the same 
 lines, in which boiled and putrid infusions of meat 
 replaced the boiled and fermented musts respectively, 
 the above results were not confirmed, for the boiled 
 infusion of meat became subsequently putrid. Helm- 
 holtz, not able to find any evidence of germ life in 
 these putrid liquids, and not suspecting, as we now 
 know to be the case, that this result could be due to 
 imperfect methods of operation, drew the inference 
 that, although alcoholic fermentation apparently was 
 to a certain extent dependent upon vital processes, the 
 l^utre faction of nitrogenous substances, on the contrary, 
 was independent of germ life. Helmholtz therefore 
 came to the conclusion that the presence of germs 
 was only a matter of secondary iinportance — putrid 
 materials possibly providing them with an attractive 
 food substance — and that such germs when present 
 might perhaps be capable of modifying to some ex- 
 tent the exact course of the putrefaction process. 
 Finally, Helmholtz stated that the position of germs 
 even in alcoholic fermentations was doubtless very 
 similar to that which relegated them in his opinion to 
 a secondary and subordinate place in putrefaction 
 processes. 
 
 Thus a cloud was cast over the brilliant and 
 stimulating work of Cagniard-Latour, Schwann, and 
 Turpin, and the obscurity was materially increased by 
 the determined opposition which Liebig maintained 
 towards their vitalistic theory of fermentation. 
 Liebig, blinded by his preconceived opinion, already 
 referred to, refused to recognise that the setting up 
 of fermentative and putrefactive processes, accom- 
 panied by the growth and multiplication of the 
 
40 PASTEUR. 
 
 fermenting and putrefying agents respectively, were 
 phenomena having no sort of analogy whatever to 
 anything taking place in reactions of a purely 
 chemical nature. Pasteur, although wholly a 
 chemist, even as Liebig, had from the very first 
 been differently imj)ressed by the essential features 
 of the problem, having at once recognised that there 
 was nothing in the whole range of chemical pheno- 
 mena which could be compared with the trans- 
 missibility or further communication and continua- 
 tion of the processes of fermentation and decay from 
 one material to another. Much in the same way as 
 he had approached the refutation of Mitscherlich's 
 memorable conclusions as to the constitution of 
 chemical compounds, Pasteur now set to work to 
 solve the problems of fermentation, not permitting 
 himself to be blinded or disheartened by contradictory 
 observations and experimental difficulties, but, with 
 infinite patience and scientific courage, startmg 
 afresh, altering the conditions, regarding failure not 
 necessarily as supporting the assumptions of the non- 
 vitalist part}', but rather attributing it to faulty 
 manipulation and his own inaptitude in conducting 
 experiments surrounded with such unusual and 
 hidden difficulties. 
 
 Pasteur had been indirectly brought in contact 
 with lermentation phenomena in the course of his 
 researches on asymmetry, for amongst the optically 
 active compounds known at the time was the amyl 
 alcohol, which is obtained as a by-product in a number 
 of fermentations, and is a constituent of the well- 
 known " fusel oil," obtained in whisky distilleries. 
 The manner in which the study of this amyl alcohol 
 
FERMENTATION STUDIES. 41 
 
 lauiiclied Pasteur into the investigation ot fermenta- 
 tion phenomena with a preconceived idea opposed to 
 Liebig's doctrine is clearly set forth in his own 
 writings. Liebig's theory would obviously interpret 
 the optical activity exhibited by aniyl alcohol as 
 conditioned by the asymmetry of the sugar from 
 which it is derived in the fermentation process : but 
 Pasteur distinctly states that he considers the molecule 
 of amyl alcohol to be too remotely related to that 
 of sugar to have preserved the dissymmetry of the 
 latter. The dissymmetry of the amyl alcohol must, 
 therefore, be a new creation, so to speak, and such 
 creation of an asymmetric molecule was, in Pasteur's 
 opinion, as we have seen, only possible by the inter- 
 vention of life. It would follow, then, almost as a 
 necessary corollary, that the fermentation in which 
 the amyl alcohol had been formed must be a vital 
 process, and not the purely chemical transformation 
 which Liebig would have us believe it to be. AVe 
 have seen what a tremendous power a preconceived 
 idea proved in the hands of Pasteur in the case of his 
 investigations on molecular dissymmetry, and we must 
 now follow the consequences which resulted from such 
 a preconceived idea in the domain of fermentations. 
 
 This brings us to the year 1857, a year moment- 
 ous in the annals of bacteriology, in which Pasteur 
 by dint of new methods brought forward new and 
 convincing proofs in support of the vitalistic theory 
 of fermentation, and communicated to the scientific 
 world his researches on the lactic fermentation, the hrst 
 of that series of masterly investigations on fermentation 
 which he was to pursue during the next twenty years. 
 
 In the lactic fermentation, which is familiar to 
 
42 PASTEUR. 
 
 everybody in the apparently spontaneous souring of 
 milk, Pasteur noticed that a greyish solid material 
 was deposited, and that the quantity of this increased 
 during the process. On examining some of this sub- 
 stance under the microscope he found that it con- 
 sisted of very minute corpuscles, rod-like in shape* 
 and quite distinct from the yeast cells observed in 
 the alcoholic fermentation. Imbued with the idea of 
 the transmissibility of the process of fermentation, 
 Pasteur took a trace of this grey material and in- 
 troduced it into a sokition of sugar, to which he had 
 added a decoction of yeast and some chalk, and soon 
 had the intense satisfaction of witnessing the lactic 
 fermentation in full activity in this artificially prepared 
 Hquid. From this fermenting Hquid he transferred 
 again a minute trace into another similar solution 
 of sugar, and so on, invariably obtaining the same 
 fermentation, in^•ariably finding also the same cor- 
 puscles in the deposit. 
 
 Pasteur, however, did not rest until he had fur- 
 nished even more conclusive proofs that the process 
 of fernientation was directly dependent upon the life 
 of these minute microscopic forms, for he at once 
 realised that Liebig and his supporters might attri- 
 bute the fermentative change in the sugar to the 
 decomposition of the albuminoids derived from the 
 decoction of yeast employed in his experiments, and 
 he therefore determined to cut off this retreat, which 
 through its inaccessibility had so long sheltered 
 Liebig's theory, and Avhich, devoid as it was of any 
 sound foundation, could not have survived even 
 for a day had it been ex[)Osed to the direct fire of 
 experimental criticism. 
 
FERMENTATION STUDIES. 43 
 
 To this end Pasteur abolished the albuminoids 
 in his fermentations altogether, replacing them by 
 ammonium salts, as a source of nitrogen for the 
 nutrition of the i'ermenting organism; and in these 
 solutions of pure sugar, with nothing but mineral 
 additions, he demonstrated that ordinary brewer's 
 yeast grew and multiplied, and that its growth w^as 
 accompanied by the conversion of the sugar into 
 alcohol and carbonic anhydride; whilst similarly those 
 totally distinct living corpuscles, to which he gave 
 the name of levure lactiqite, proliferated in solutions 
 of the same composition, their multiplication being 
 accompanied by the transformation of the sugar into 
 lactic acid. 
 
 The conclusions drawn by Pasteur from these 
 laborious researches are summarised in the following- 
 words, as sober as they are incisive and uncom- 
 promising : — 
 
 " As for the interpretation of the group of new 
 facts which I have met with in the course of these 
 researches, I am confident that whoever shall judge 
 them with impartiality, will recognise that the alco- 
 holic fermentation is an act correlated to the life and 
 to the organisation of these corpuscles, and not to 
 their death or their putrefaction, any more than it 
 will appear as a case of contact action in which the 
 transformation of the sugar is accomplished in the 
 presence of the terment without the latter giving or 
 taking anything from it." 
 
 Both the memoir on the lactic and that on the 
 alcoholic fermentation published in 1860 end with 
 the above words, as though Pasteur enjoyed hearing 
 the sound of the hammer on the last nail knocked 
 
44 PASTEUR. 
 
 into the coffin of the dogma which had by so 
 many years delayed the scientific prosecution of 
 the study of fermentations on the hnes inaugurated 
 by Cagniard-Latour and Schwann. It was Pasteur's 
 firm conviction that the fermentative process de- 
 j^ended on the hfe of the organism, and his repug- 
 nance to the shallow form of words dignified by the 
 name of theory which simply served to cloak the 
 chemical ignorance of the day concerning these mys- 
 terious phenomena of fermentation, that stimulated 
 and spurred him on to undertake this extraordinarily 
 comprehensive and laborious series of researches. 
 
 The amount of new experimental material col- 
 lected by Pasteur in connection with this work fills 
 the reader with admiration ; whilst his pre-eminent 
 power of seeing what others had failed to observe 
 before him, is again exemplified in his discovery of 
 succinic acid and glycerine as the invariable products 
 of the alcoholic fermentation of sugar. 
 
 But these researches, besides being of fundamental 
 importance in throwing light upon one of the oldest 
 but hitherto obscurest departuients of scientific in- 
 vestigation, opened up an entirely new field of work ; 
 for with the inauguration by Pasteur of artificial 
 culture solutions, that path was lirst indicated which 
 has gradually expanded into the fascinating science 
 of Bacteriology. 
 
CHAPTER lY. 
 
 DISCOVERY OF ANAEROBIC LIFE. 
 
 During the progress of these ferraentation researches 
 an important event had occurred m Pasteur's life, for 
 October, 1857, witnessed his removal from the pro- 
 vincial Lille to the metropolis of France, in the 
 palmiest days of the Second Empire. His advance- 
 ment to the post of director of scientific studies at the 
 Ecole Normale in Paris was not, however, an unmixed 
 advantage to Pasteur, for it deprived him of that 
 which he most valued — a scientilic laboratory. Nor 
 did there appear to be any prospect of obtaining one, 
 as the French Government of forty years ago appears to 
 have been on much the same level of enlisfhtenment 
 in reo'ard to scientitic work as our own rulers of both 
 parties to-day. Berthelot, already distinguished for 
 most important investigations, was yet only a demon- 
 strator at the College de France ; Claude Bernard, the 
 great physiologist, was compelled to work in a 
 cramped and unhealthy laboratory ; and Pasteur was 
 publicly informed by a Government minister that the 
 budget had no means at its disposal to provide him 
 with the sum of 1,500 francs (£60) a year for experi- 
 mental researches. Pasteur, however, was not to be 
 baffled by such obstacles, and what the nameless and 
 long-since forgotten minister would not concede was 
 procured at Pasteur's private expense, and a labor- 
 atorv was constructed out of one of the o-arrets of the 
 Ecole Normale. 
 
46 PASTEUR. 
 
 Wholly absorbed by his work, and dividing his 
 time between his official duties and his beloved labor- 
 atory, Pasteur saw scarcely anyone except Biot, 
 Dumas, De Senarmont, and Balard, with whom he 
 discussed divers scientific questions arising out of 
 the daily progress of his researches. 
 
 And now one brilliant discovery succeeded another 
 in rapid succession, but there was one which, in re- 
 spect of its wide and fundamental significance in 
 relation to the economy of nature, is perhaps without 
 an equal amongst his numerous and great achieve- 
 ments. Moreover the manner in which this discovery 
 was made affords another illustration of his penetrat- 
 ing scrutiny of the smallest detail in the phenomena 
 which passed before him. 
 
 It was in studying the butyric fermentation that 
 he took, as was his wont, a drop of the fermenting 
 liquid and examined it in the thin film obtained by 
 mounting on slip and cover-glass under the micro- 
 scope, but on this occasion he was struck by the fact 
 that along the periphery of the drop, wherever it was in 
 contact with the air, the bacilli appeared motionless and 
 inert, whilst the bacilli in the central portion ot the drop 
 were executing those remarkable movements which 
 form one of the most fascinating spectacles which the 
 microscope provides. The question at once arose in 
 Pasteur's mind, were these vibrios in the centre flee- 
 ing from the oxygen at the peripher}^ and had the 
 latter paralysed the activity of those which had been 
 brought in contact with it ? There was nothing more 
 easy than to interrogate them on the subject, by pass- 
 ing a stream of air through a flask containing a liquid 
 in butyric fermentation; nor had he long to wait for 
 
DISCOVERY OF ANAEROBIC LIFE. 47 
 
 an answer: the fermentation soon slackened and was 
 ultimately arrested. 
 
 Thus Avas science enriched by the revelation that 
 there exist living forms which grow, multiply, and 
 develop mechanical energy in the absence of that 
 oxygen, which it had hitherto been regarded as one of 
 the most far-reaching discoveries to have shown was 
 indispensable for the whole living creation. Moreover, 
 this remarkable life was actually shown to be either 
 destroyed or paralysed by the very element upon the 
 presence of which all life was supposed to depend. 
 
 We have seen already that Pasteur's first discovery 
 of the resolution of racemic acid into the left and right- 
 handed tartaric acids was received with increduHty; 
 and it is not surprising that such a revolutionary 
 discovery as this of anaerobic life, as he called it, 
 should have raised a perfect storm of opposition. 
 
 But Pasteur's confidence in his own results was 
 not to be shaken by that kind of criticism which is 
 based on reverence for tradition', nomenclature, and 
 classification ; and his firm, uncompromising, if not de- 
 fiant attitude towards his opponents is well illustrated 
 by the following words — " Que le progres de la science 
 fasse de ce vibrion une plante ou un animal, peu im- 
 porte : c'est un etre vivant, done de mouvement, que 
 vit sans air et qui est ferment." This anaerobic life of 
 the butyric ferment was not allowed to remain an iso- 
 lated observation without bearing on other facts; but on 
 the contrary, its relationship to other known facts 
 was at once discerned by Pasteur, who already in the 
 same year, 1861, makes another connnunication to 
 the Academy of Sciences in which he develops in 
 outline that celebrated theory of fermentation which 
 has served to stimulate so many valuable researches. 
 
48 , PASTEUR. 
 
 The considerations which led to the evohition of 
 this theory in Pasteur's mind are apparent from the 
 following passage, with which he concludes this note: — 
 
 " Thus, beside all the beings known to-day, which with- 
 out exception (as is believed) cannot breathe and nourish 
 themselves except by the assimilation of free oxygen gas, 
 there would be a class of beings possessing such vigorous 
 respiratory power that they are able to live without the 
 intiuence of the air by taking oxygen from certain compounds, 
 thus occasioning in the latter a slow and progressive decom- 
 position. This second class of organised beings would lie 
 constituted by the ferments, similar in every respect to the 
 beings of the first class, living even as they are, assimilating 
 after their fashion carbon, nitrogen, and phosphates, and 
 also standing, like them, in need of oxygen, but differing 
 from them, inasmnch as they can, in the absence of free 
 oxgyen ga?;, take oxygen from compounds of little stability." 
 
 Pasteur, who before had had passages of arms 
 with the great Liebig, was now gradually approach - 
 inor that combat which is one of the most memorable 
 in the whole annals of scientific histor}^, and upon 
 Avhich the attention of the world, both scientific and 
 unscientific, was to be riveted. 
 
 One of the most striking characteristics of Pasteur's 
 genius was the comprehensive view which he took 
 of scientific phenomena, and the clearness with 
 which he mapped out before him the subtle re- 
 lationship existing between facts of apparently 
 the most varied and disconnected order. Nothing 
 seemed to escape his eager and accurate scrutiny, 
 and whilst apparently engrossed with one problem, 
 his mind was busily engaged in surveying further 
 ground at a distance which would of necessity 
 have to be broken, made to yield up its fruitful 
 
DISCOVERY OF ANAiillOUIC LIFE. 49 
 
 secrets, and in its turn become annexed to that 
 new territory of science which his genius had 
 discovered and revealed. 
 
 Thus it was that Pasteur from a study of fermen- 
 tation was led to a consideration of the processes of 
 putrefaction and decay, which lie was not slow in 
 announcing as also dependent upon the presence 
 of living organisms. 
 
 That putrefactive processes were possibly asso- 
 ciated with livin<2r or^^anisms was no new su^'oestion, 
 but had been long ago brought forward by those 
 who discovered so-called lyiicroscopic animalculcu 
 in decomposing materials ; but the time was then 
 not ripe for the production of a positive proof, and 
 although the hypothesis remained, it was left for 
 Pasteur to rigidly demonstrate its complete justifica- 
 tion. It is dilii(;ult for us at the present time to 
 realise the necessity for such a proof, and it is 
 particularly interesting now to read the contemptuous 
 words with which Licbii>: discussed and thouQ-ht to 
 dismiss the vitalistic theory of putrefaction. " Those 
 who attempt to explain the putrefaction of animal 
 substances by the presence of animalcules," wrote 
 Liebig, " argue much in the same way as a child 
 who imagines he can explain the rapidity of the 
 Rhine's flow by attributing it to the violent agitation 
 caused by the numerous water-wheels of Mainz, in 
 the neighbourhood of Bingen. Can we legitimately 
 regard plants and animals as the means whereby 
 other organisms are destroyed, when theij- own 
 constituent elements are condemned to undergo the 
 same series of putrefaction phenomena as the 
 creatures which preceded them ? If the fungus is 
 D 
 
50 PASTEUR. 
 
 the agent of the oak's destruction, if the microscopic 
 animalcule is the agent in the putrefaction of the 
 elephant's carcase, I ask in my turn, what is the 
 agent which Avorks the putrefaction of the fungus 
 and the microscopic animalcule when life has been 
 removed from these two organised bodies ? " 
 
 Liebig's insistence upon an explanation of these 
 processes on a physiologico-chemical basis was justi- 
 fied, for the part played by micro-organisms in 
 fermentative and putrefactive phenomena Pasteur 
 himself regarded as but the first phase in that cycle 
 of changes which ultimately restores all substances to 
 their original source, the atmosphere and soil. 
 
 Pasteur now proceeded to show that the final 
 destruction of animal and vegetable matters took place 
 in consequence of a process of slow combustion, by 
 the fixation of atmospheric oxygen. 
 
 The complex materials produced in the preliminary 
 processes of fermentation and decay Pasteur attributed 
 to the agency in great part of anaerobic microscopic 
 forms performing their work of decomposition in the 
 absence of oxygen, these complex materials being 
 again, in their turn, attacked by aerobic miscroscopic 
 forms, dependent upon the presence of oxygen, and 
 Pasteur, by most ingenious experiments, actually 
 showed how these minute living forms did indeed 
 possess the property of fixing atmospheric oxygen. 
 
 He took two sets of fiasks; in one series he placed 
 an aqueous decoction of yeast, together with solutions 
 of sugar, milk, etc., which had been previously heated, 
 and to these fiasks only air was admitted, which he 
 designated as pure — i.e. from which all dust particles 
 had been removed. The second series of flasks also 
 
DISCOVERY OF ANAEROBIC LIFE. 51 
 
 contained an aqueous emulsion of yeast, but no 
 precautions were taken either to heat the sohitions 
 or to purify the air which was admitted. Both sets 
 of flasks were then kept at a temperature of from 
 25 to 35 deg. Centigrade, and after the lapse of some 
 time the air of all was carefully analysed. 
 
 In the flasks containing heated liquid, and to 
 which only pure air had been admitted, the air present 
 still contained large quantities of oxygen, but in the 
 other flasks, where the access of microscopic organisms 
 was not in any way impeded, there Avas absolutely no 
 oxygen present, its place having been taken by carbonic 
 acid gas. This absorption and fixation of atmospheric 
 oxygen had taken place in the course of a few days, 
 whilst in the flasks in which microscopic life was 
 absent a quantity of free oxygen Avas found even after 
 several years. 
 
 Thus Pasteur was able to again demonstrate the 
 stupendous importance of micro-organisms in the 
 economy of nature; for only with their assistance is 
 the organic debris in the world broken up and pre- 
 sented to us ao'ain in a serviceable form, instead of 
 encumbering the whole surface of the globe and so 
 rendering it uninhabitable, as would inevitably be 
 the case but for the agency of these minute forms of 
 living matter. 
 
 Pasteur, in his investigations of fermentative 
 phenomena, had thus, by the year 1861, shown, firstly, 
 the worthlessness of the form of words by means of 
 which Liebig and the chemists of the time sought to 
 banish all biological considerations from the study of 
 these questions; secondly, he had worked out a 
 method of scientifically attacking these problems, in 
 D 2 
 
52 PASTEUR. 
 
 which for the first time both the chemical and bio- 
 logical aspects of the subject received their due share 
 of attention. 
 
 It is here that we are again brought in contact 
 with those pecuhar endowments which are the key to 
 Pasteur's success throughout his career. Just as his 
 brilHant achievements in the domain of molecular 
 asymmetry were due to the facihty which he dis- 
 played in bridging the gulf between pure physics and 
 chemistry, and co-ordinating the facts belonging to 
 each, so here again we find him closing the breach 
 between chemistry and biology, and moving with equal 
 facility along the main lines of each of these sciences ; 
 and it is to this altogether exceptional versatility 
 that we owe his successful exploration of borderlands 
 which can only be traversed by those capable of 
 adapting themselves to the special means of loco- 
 motion necessary in two countries differing widely in 
 their character and configuration. 
 
 Thirdly and finally, by the systematic use of this 
 new method of investigating fermentation phenomena 
 he had discovered the possibility of life without air, 
 and had collected suflicient experimental data to 
 venture upon a new theory of fermentation. The 
 additional researches which this new theory stimulated 
 were deferred for some years in consequence of his 
 attention being directed to certain phenomena closely 
 related to fermentation, and demanding a full and 
 final explanation before further progress could be 
 made in, to use his own words, "ces travaux dont la 
 difficulte ne me laisse ni treve ni repos." 
 
CHAPTER V. 
 
 SPONTANEOUS GENERATION CONTROVERSY. 
 
 Although Pasteur's victories in the field of fermenta- 
 tion had been won in the teeth of the opposition of 
 the entire scientific world, he was on the eve of an 
 even fiercer battle, in Avhich he was to measure his 
 strength almost single-handed against some of the 
 subtlest intellects of the day. 
 
 The inquiry to which Pasteur in the next instance 
 devoted his commanding energies might appear to us 
 at the present time almost a work of supererogation, 
 for during more than twenty years past we have 
 heard nothing of that great question which has 
 exercised the mind of man from the earliest asres : 
 
 o 
 
 Does life originate spontaneously ? The history of this 
 subject is, however, of great interest in many ways — 
 chiefly, perhaps, on account of the proof which it 
 furnishes of the danger of accepting evidence on 
 authority. 
 
 Some of the greatest thinkers and observers of 
 past ages have had very definite views on this subject 
 of the generation of life. Aristotle categorically 
 afiirms that " every dry body becoming moist, and 
 every moist body becoming dry, engenders animals." 
 Virgil is more specific still in asserting that bees 
 originate within the putrefying carcase of a young 
 bull :— 
 
54 PASTEUR. 
 
 "Aspiciunt liquefacta bourn per viscera toto 
 Stridere apes utero, et ruptis effervere costis." 
 
 Van Helmont actually supplies the prescription 
 for producing by spontaneous generation the domestic 
 mouse. His formula consists in squeezing some soiled 
 linen into the mouth of a vessel containing some 
 grains of wheat, which arrangement gives rise to the 
 transmutation of the wheat into mice in the course of 
 about twenty-one days. The mice so generated are 
 said to make their appearance in the adult state, both 
 sexes being duly represented. 
 
 In the present century the advocates of spontaneous 
 generation had abandoned their ground as regards 
 such tangible forms of life as bees, frogs, and mice, 
 and had restricted their views to those minutest of 
 organisms which the microscope had rendered visible. 
 
 The interrogation of nature by direct experiment 
 in regard to this problem does not commence until 
 the middle of the last century, when, in 1748, Father 
 Needham, an Irish priest, declares in favour of spon- 
 taneous generation, convinced by the result of ex- 
 periments which he had made on quite modern lines, 
 viz., of placing putrescible substances in vessels which 
 he subsequently hermetically sealed and submitted to 
 heat. He assumed that the heat would destroy all 
 life in these materials, and" when he afterwards found 
 that an abundance of microscopic living forms made 
 their appearance in these vessels, he concluded that 
 they had arisen by spontaneous generation. 
 
 That this investigation carried conviction at the 
 time is shown by the fact that within two years of its 
 publication he was elected a Fellow of the Royal 
 
SPONTANEOUS GENERATION CONTROVERSY. 55 
 
 Society of London, and a little later lie had tlie 
 honour of" becoming one of the eight Associates of 
 the French Academy of Sciences. 
 
 It was not until 1765 that these results were 
 challenged by the Abbe Spallanzani in a dissertation 
 which led to a lively dispute between these two 
 divines. 
 
 Spallanzani repeated Xeedham's experiments, but 
 he heated the hermetically sealed vessels more 
 thoroughly and for a longer period of time, with the 
 result that no signs of life subsequently made their 
 appearance. Father Needham, however, raised the 
 objection that this additional "torture" — to use his 
 own expression — had enfeebled or perhaps totally 
 destroyed the " vegetative force " of the substances 
 and •' entirely corrupted " the air present in the 
 vessels. This objection was subsequently strengthened 
 by the discovery made by Gay Lussac that the air 
 present in the hermetically sealed vessels containing 
 various vegetable and animal substances preserved by 
 Appert's process was entirely destitute of oxygen. 
 
 Schwann, however, dispelled this objection in 
 1837, by introducing an important modification into 
 the method of experiment. He sterilised the putres- 
 cible substance in the vessel by heat, and then allowed 
 air to enter ; but this air, before being admitted, was 
 passed through a tube heated nearly to the boiling- 
 point of mercury in a bath of fusible metal. Under 
 these conditions, in nearly all cases the putrescible or 
 fermentable substances remained intact ; but the ex- 
 ceptional experiments in which a contrary result was 
 obtained, shook even the faith of their author in the 
 trustworthiness of the investigation. 
 
56 PASTEUR. 
 
 Similarly indecisive results were obtained by Ure, 
 Helmholtz, Schultze, who passed the air through 
 chemicals (caustic potash and sulphuric acid), and 
 by Schroeder and Dusch, who in 1854-59 again 
 altered the modus operandi by filtering the air 
 through cotton-wool. 
 
 This unsatisfactory state of affairs was brought 
 to a crisis in the year 1859, when Pouchet, Director 
 of the Natural History Museum in Rouen, appeared 
 with a paper before the Academy of Sciences, in 
 which he threw down the gauntlet to the vitalists 
 declaring, " Les adversaires de la generation spontanee 
 pretendent que les germes des etres microscopiques 
 existent dans I'air, que I'air les charrie, les transporte 
 a distance. Eh bien ! que diront ces adversaires si je 
 parviens a determiner la generation de quelques etres 
 organises en substituant un air artiticiel a celui de 
 I'atmosphere ? " 
 
 Pouchet's method of experiment consisted in 
 taking a flask of boiling water, which he hermetically 
 sealed and then plunged upside-down into a basin of 
 merciuy. When the water had become quite cold, 
 he opened the flask under mercury and introduced 
 half a litre of pure oxygen, and also a small quantity 
 of hay previously exposed for a long time to a very 
 high temperature. Thus Pouchet conceived that ho 
 had satisfactorily removed every loophole for the 
 admission of living organisms into his flask, and it 
 was with triumph that he appeared a few days later 
 before the Academy with his flask, the contents of 
 which exhibited growths. 
 
 " Whence had they come, and how could their 
 presence be accounted for except on the theory 
 
SPONTANEOUS GENERATION CONTROVERSY. 57 
 
 of spontaneous generation ? " confidently demanded 
 Pouchet. 
 
 In the hopes of putting an end to a controversy 
 which appeared only to increase in difficulty and 
 complexity as time went on, the Academy in 1860 
 gave as a subject for a prize-competition : " Essayer, 
 par des experiences bien faites, de jeter un jour 
 nouveau sur la question des generations spontanees." 
 
 It is at this moment that Pasteur enters the lists, 
 and the circumstance that we have for more than 
 twenty years heard nothing of the doctrine of spon- 
 taneous generation, is due to the effectual manner in 
 which he successively hurled into the dust the several 
 champions who appeared on its behalf in the intel- 
 lectual tournament which followed. 
 
 The intimate contact in which Pasteur had lived 
 with these microscopic forms during his researches on 
 fermentation, naturally led him to take a deep in- 
 terest in this controversy, although many of his scien- 
 tific friends — amongst whom were Biot and Dumas 
 — strongly dissuaded him from taking an active 
 part in the discussion, fearing that nothing but loss 
 of valuable time would come of joining in this 
 controversy. 
 
 But Pasteur was renowned for the audacity, if we 
 may use the word, with which he singled out subjects 
 for research. " He makes me uneasy," remarked one 
 of the comrades of his youth, who had early divined 
 the extraordinary gifts of this eager and silent worker. 
 " He does not recognise the limits of science, he only 
 loves quite insoluble problems ; " and true enough, he 
 was not to be deterred from attackino- this, to his 
 colleagues, hopeless and inscrutable question, and he 
 
58 PASTEUR. 
 
 commenced by quickly dispelling the momentary 
 triumph achieved by Pouchet. By means of most 
 skilfully planned experiments he showed that the 
 surrounding air is full of dust particles, and that to 
 these dust particles living organisms are attached. 
 He repeated the experiments of Schroeder and Dusch, 
 but instead of using ordinary cotton-wool he em- 
 ployed gun-cotton as the filtering material for the 
 air, and by subsequently dissolving this in a mixture 
 of alcohol and ether he showed that it had arrested 
 a multitude of living organisms. He pointed out that 
 Pouchet had neglected an important precaution for 
 insuring the absence of all life in his flask and hay 
 infusion ; that this source of error lay in the use 
 of mercury, from the surface of which the living 
 organisms had found their way into the flask. 
 
 Pouchet and his supporters, however, once more 
 took shelter behind the favourite hypothesis, supported 
 so eloquently by Gay Tjussac, that decomposition was 
 dependent upon the presence of oxygen, and the 
 opinion soon became current in the scientific world 
 that the smallest bubble of oxygen or air was sutiicient 
 to produce putrefaction. If, urged Pouchet, decom- 
 position is due to the germs present in a minute 
 bubble of air, then the latter must of necessity be so 
 heavily laden with living forms that we should be 
 surrounded by a thick fog, " dense comme du fer." 
 
 Pasteur, however, demonstrated as had Schwann 
 before him, the erroneous nature of Gay Lussac's 
 oxygen theory of decomposition, but in this new 
 argument he perceived another important source of 
 error which it behoved him to at once correct. 
 
 He recognised that the assumption as to a very 
 
SPONTANEOUS GENERATION CONTllOVEUSY. 59 
 
 minute quantity of air being in every case capable of 
 provoking germ life was incorrect, and he proceeded, 
 by means of a series of experiments as simple as they 
 were conclusive, to show how the air may vary in its 
 richness as regards germ life. 
 
 A small quantity of clear broth was introduced 
 into a number of little flasks, the necks of which 
 were then drawn out to a fine aperture. The contents 
 were then heated to boiling for some time, and by so 
 doing, not only was the air driven out of the flask, 
 but the contents were rendered sterile ; after this the 
 aperture was closed by heating it in a flame. 
 
 Armed with his little battery of such flasks, Pasteur 
 started for Arbois. Here, in the open country, away 
 from all houses, he opened twenty ; on the lower heights 
 of the Jura mountanis twenty more were opened ; 
 and again the same number at the Montanvert close 
 to the Mer de Glace, at a height of upwards of 6,000 
 feet. On re-sealing all the flasks, he straightway 
 returned to Paris and deposited them in the bureau 
 of the Academy of Sciences in November, 1860. 
 
 The results, which were awaited with the utmost 
 interest, were as follows : of the twenty flasks opened 
 near Arbois eight developed living organisms ; of the 
 twenty opened on the Jura five became affected; of 
 the twenty flasks, however, opened on the Montanvert 
 only one exhibited germ life. 
 
 Thus Pasteur once more disposed of the oxygen 
 theory of putrefaction by pointing to the flasks in 
 which, despite the access of oxygen, no germs made 
 their appearance ; but he did more, he demonstrated 
 the fallacy of Pouchet's argument that if germs were 
 present in the air they nuist be present in such 
 
60 PASTEUR. 
 
 numbers as to render it opaque, and at the same time 
 he srave the first indication of the uneven manner 
 in which micro-organisms are distributed in the 
 atmosphere. 
 
 Pasteur, however, was not yet satisfied that he had 
 exhausted every argument which might be raised 
 ao-ainst the correctness of his conchisions, and this 
 time he anticipated attack, suggesting that during 
 the boihng of the Hquids he employed, the latter 
 mip-ht have become so changed in chemical composi- 
 tion as to render them incapable of exhibiting the 
 supposed phenomenon of spontaneous generation; an 
 objection already, it will be remembered, raised by 
 Father Needham to the acceptance of Spallanzani's 
 experiments. To silence this objection, Pasteur 
 devised an experiment as remarkable for its extreme 
 simplicity as for its convincing force ; he placed his 
 orgfanic infusions in flasks, the necks of which were 
 each subsequently drawn out into a long tube curved 
 dowuAvards and then upwards as in the following 
 figure. The extremity was left open, so that on 
 sterilising the contents by boiling and then allowing 
 it to cool, the air would obviously enter by this open 
 tube. The putrescible infu^sion, however, remained 
 unaltered, and Pasteur proved that the reason for this 
 was not that the liquid was incapable of developing 
 germs, but that the germs suspended in the incoming 
 air had been all deposited in the bend of the tube. 
 On inclining the flask, so as to allow a few drops of 
 the liquid to run into the bend, the latter soon 
 developed growtlis. Thus once more the oxygen 
 theory of putrefaction was effectually set aside, and 
 Needham's contention as to the devitalisation of 
 
SPONTANEOUS GENERATION CONTROVERSY. 61 
 
 the liquid during heating likewise dismissed once 
 and for all. 
 
 But yet another difficult}^ confronted Pasteur, and 
 one which had so often perplexed and blinded his 
 predecessors, and this w^as the fact that milk de- 
 veloped microscopic growths, even after being sub- 
 jected to boihng for some minutes. Instead, however, 
 of recognising in this any support to the theory of 
 
 PASTEUR S I'LASK, 
 
 spontaneous generation, he inferred that the milk 
 doubtless contained originally some peculiarly refrac- 
 tory organisms, and by raising the temperature of 
 sterilisation to 110° C. he found, in pomt of fact, that 
 no growths did subsequently make their appearance. 
 
 During the progress of these investigations, Pasteur 
 was continuously harassed by the publications of his 
 opponents, who claimed to have obtained results 
 entirely at variance with his own. Tliis opposition 
 was long endured, but his patience ultimately gave 
 way wdien some of his experiments were directly 
 challenged by Pouchet, Joly, and Musset, who asserted 
 
62 PASTEUR. 
 
 that in repeating them they had obtained diametrically 
 oj)posite results. 
 
 To put an end to this unbearable criticism, Pasteur 
 conceived the idea of settling the dispute by a method 
 which has recently played such an important part in 
 the arrangement of a great political difference be- 
 tween this country and America. Pasteur determined 
 to have recourse to arbitration. He appealed to the 
 Academy of Sciences to appoint a special commission 
 to judge between himself and his opponents. What- 
 ever may be the value of arbitration as a means of 
 settling disputes in the political and industrial worlds, 
 there can be no doubt that it is wholly unsuited as a 
 means of arriving at the truth in a scientific conflict, 
 for in such matters there is but one court of appeal — 
 Time and the opinion of Posterity. 
 
 The commission, however, was duly appointed, and 
 the method of procedure and the result were as re- 
 markable as they Avere instructive. It was arranged 
 that both parties should a23pear at the bar of the 
 Academy and there perform their rival experiments."^ 
 On the day appointed Pasteur, and his assistants, 
 arrived laden with apparatus which they were ready 
 at once to put into operation. Pouchet and his ad- 
 herents were there also, but they had come empty- 
 handed. They asked for time, and urged that the 
 weather was unpropitious to the success of their 
 
 * Some of the ilasks containing putiescible infusions jjrepared by 
 Pasteur himself for this occasion are still preserved with reverential 
 care at the Institut Pasteur. On the labels, now yellow with age, 
 may still be read the signature of M. lialard, the secretary of the 
 Commission. Even after the lapse of all these years the liquids in 
 these flasks are as clear as they were on the day of preparation. 
 
SPONTANEOUS GENERATION CONTROVERSY. 63 
 
 experiments, which had been made at a different 
 season of the year ! 
 
 The Commission, however, would not accede to 
 the remand. Pasteur successfully performed his ex- 
 periments, and a strong judgment was given in his 
 favour, pronounced by M. Flourens, Secretary of the 
 Academy of Sciences, with all the solemnity and 
 finality of a judge delivering a sentence. 
 
 "As long as my opinion was not formed 1 had 
 nothing to say ; to-day it is formed and I speak it. 
 The results are conclusive. To have animalcules, 
 what, then, is essential if spontaneous generation is 
 true ? Air and putrescible liquids. Now, M. Pasteur 
 puts air in contact with putrescible liquids and nothing 
 happens. There is, therefore, no spontaneous genera- 
 tion. To still doubt is not to understand the 
 question." 
 
 But before the superior court of Time even the 
 most distinguished Academicians must bend, and we 
 now know that Pasteur and his opponents were in 
 reality both right as regards what they had actually 
 observed in their respective experiments. 
 
 The facts are these : Pasteur had used infusion of 
 yeast as the putrescible material in his experiments, 
 Pouchet had used infusion of hay in his ; the infusion 
 of yeast is easy, the infusion of hay excessively difficult 
 to sterilise by heat. The heat applied by Pasteur was 
 sufficient to sterilise the jeast infusion, it was in- 
 sufficient to sterilise the hay; and consequently the 
 heat applied by Pouchet, which was the same as that 
 used by Pasteur, failed to remove the life originally 
 present in the hay infusion, and quite irrespectively 
 of the access of any fresh germs from the air 
 
64 PASTEUR. 
 
 afterwards admitted, Pou chefs flasks would have 
 subsequently exhibited life, the latent condition of 
 the germs still present in the hay infusion being 
 changed into activity as soon as they obtained a 
 supply of oxygen from the air. Neither Pasteur nor 
 his opponents were, however, aware at that time of 
 this fact. 
 
 Through the want of confidence in themselves 
 exhibited by Pouchet and his associates in this 
 extraordinary trial, and by the academic tribunal 
 giving judgment in default, the knowledge of the 
 whole truth was delayed several years, for doubtless 
 the authoritative pronouncement of the Academy 
 succeeded in protecting Pasteur from his French 
 antagonists, throttling renewed research in the 
 country in which their judgment was accej^ted as 
 final. Fortunately, however, for science, it could not 
 blockade research throughout the world ; it could not 
 protect him from attack by scientific foes owning no 
 allegiance to the august body whose aid had been so 
 successfully invoked. 
 
 The prize before referred to, offered by the 
 Academy, was unanimously awarded to Pasteur, and 
 in 1862, at the early age of forty, he Avas elected 
 a member of the Academy of Sciences. 
 
 In 1876 the contest was reopened, and this time 
 by one of our own countrymen, Dr. Bastian, and it 
 was in repeating the experiments and fighting the 
 conclusions of this new antagonist that the truth 
 with regard to spontaneous generation was finally 
 established on an indestructible basis by Pasteur. 
 
 Pasteur and his assistants set to work with 
 renewed zeal, and discovered that the difficulties 
 
SPONTANEOUS GENERATION CONTROVERSY. 65 
 
 presented by Bastian depended upon the fact that 
 micro-organisms exist which are more difficult to 
 destroy by heat than Pasteur himself had before sus- 
 pected, and that they may remain dormant .and to all 
 appearance absent in infusions until they obtain the 
 opportunity to assert themselves or multiply. " C'est 
 le concours des germes et de I'oxygene/' declared 
 Pasteur when Bastian maintained that the develop- 
 ment of life in these heated infusions was due to 
 spontaneous generation. 
 
 The experiments which Pasteur conducted to 
 prove his case had a convincing finality which 
 admitted of no further dispute, and his conclusions 
 have been accepted by a whole generation of scientific 
 men who have unhesitatingly endorsed the statement 
 made by him in the following words : " No ; there is 
 to-day no known circumstance which permits us to 
 affirm that microscopic beings have come into the 
 world without germs, without parents like unto 
 themselves. Those who held that they do have been 
 the plaything of illusions, of experiments badly made^ 
 tainted with errors, which they have not known how 
 to perceive, or which they have not known how to 
 avoid." " La generation spontanee est une chimera" 
 
 In looking back upon this period of Pasteur's 
 career, one is disposed to regret that his great powers 
 should have been so long absorbed in this work of 
 exterminating a mere superstition ; but as a matter of 
 fact, much good came of this crusade in a number of 
 ways. Incidentally, experiments, which have now 
 become classical, were made on the distribution of 
 micro-organisms in our surroundings, such as air and 
 water, whilst healthy urine and the blood of normal 
 E 
 
66 PASTEUR. 
 
 animals were in 1862 and 1863 shown to be free 
 from microbes and capable of being preserved without 
 alteration for an indefinite period of time, provided 
 that they were collected under suitable precautions. 
 Van der Broeck had, indeed, already in 1857 and 
 1858 proved that grape-juice, white and yolk of egg, 
 gall, urme, and arterial blood, if suitably collected, 
 could be preserved without change in their natural 
 condition : whilst, subsequently, sterile milk in its 
 natural state was obtained direct from the udder 
 by Roberts, Lister, Cheyne, Meissner, and others. 
 
 The spontaneous generation controversy was 
 moreover, highly fertile in developing the general 
 methods of bacteriological research, and many of the 
 most familiar operations employed in the study of 
 micro-organisms date from this period. 
 
CHAPTER VL 
 
 STUDIES ON THE VINEGAR ORGANISM. 
 
 Pasteur had thus fully justified himself before Biot 
 and Dumas, and those other scientific friends who 
 had taken so unfavourable a view of this excursion 
 from fermentation studies into a region of investiga- 
 tion, from which alone De Senarmont had ventured 
 to prophesy he might not emerge empty-handed. 
 " Laissez faire Pasteur/' he said to Biot, " s'il ne trouve 
 rien dans la voie ou il s'engage, soyez tranquille, il 
 n'y restera plus. Mais je serais surpris qu'il ne 
 trouvat rien." 
 
 The fame of and interest in Pasteur's researches 
 had now passed beyond the pale of the scientific 
 world, and had attracted the attention of practical 
 men, and the year 1862 finds him once more 
 immersed in fermentation studies, to which he had 
 returned, armed with all the weapons and experience 
 of which he had become possessed in his recent 
 exploits in the spontaneous generation controversy. 
 
 About this time we hear of him delivering an 
 address to the vinegar manufacturers of Orleans, an 
 address which has since become memorable by reason 
 of the important revelations which it brought before 
 the industrial world concerning the production of 
 vinegar. 
 
 The city of Orleans has long been famous for its 
 E 2 
 
68 PASTEUR. 
 
 vinegar factories, and the method in vogue when 
 Pasteur commenced his studies on this subject con- 
 sisted in nearly filhng vats with a mixture of vinegar 
 and the wine to be acetified. In those vats in which 
 the process is taking place satisfactorily the surface 
 of the liquid becomes covered with a fragile pellicle, 
 which the manufacturer watches over with the 
 greatest care lest it should become submerged or 
 disturbed in any way. Long and bitter experience 
 has taught him the importance of this pellicle, and 
 that, provided it remains intact on the surftice of the 
 liquid, all will go well ; but that if by any chance this 
 thin veil should get broken up, the process will be 
 interrupted, and that nothing then remains but to 
 endeavour to produce a new one — a matter often of 
 great difficulty, and involving not only loss of time 
 but of money also. 
 
 What, then, is the nature of this pellicle, at once 
 so precious and so fragile ? Pasteur had asked him- 
 self this question long ago, and had thought over it 
 frequently, and it was natural, therefore, that on re- 
 suming his fermentation studies he should begin by 
 endeavouring to elucidate this mystery in vinegar 
 manufacture. 
 
 In accordance with his anticipations, he discovered 
 that the importance of this pellicle consists in its being 
 produced by, and, in fact, consisting of, certain micro- 
 organisms whose function it is to convey the oxygen 
 of the air to the liquor in the vats, yielding by this 
 oxidation the highly-prized vinegar. The conversion 
 of wine into vinegar he thus showed to be the 
 work of a minute rod-like organism which he 
 called onycodernia aceti, and which in its relation- 
 
STUDIES OX THE VINEGAR ORGANISM. ■ 69 
 
 ship to oxygen was the precise antipodes of the 
 butyric ferment which lie had previously discovered 
 (see p. 4(3). 
 
 It is to the discovery of the butyric and acetic 
 ferments respectively that we owe the introduction of 
 the terms anacrohic and aerobic, devised by Pasteur 
 and his colleague, the professor of Greek at the Ecole 
 Normale, to designate the respective idiosyncrasies of 
 these two microbes towards air — terms which have 
 since become household words amono-st bacteriolo- 
 gists. So carefully did Pasteur study the habits and 
 mode of life of this the latest addition to his microbial 
 nniseum, that he was able to indicate to these ex- 
 perienced employers of labour at Orleans the manner 
 in which it ougiit to be housed, fed, and treated, in 
 order to induce it to accomplish the maxinuim 
 amount of work in the shortest period of time and 
 for the lowest possible wage. He pointed out that? 
 instead of waiting the customary two or three months 
 for the completion of the process, the vinegar could 
 be elaborated in from eight to ten days by simply 
 exposing the vats containing the mixture of wine and 
 vinegar to a temperature of from 20 to 25 degs. Centi- 
 grade, and sowing on the surface a small quantity of 
 this organism. 
 
 In order to impress upon his scientific colleagues 
 at the Academy of Sciences some idea of the fabulous 
 rapidity with which this minute microbe could multi- 
 ply, Pasteur declared when reading his memoir that 
 he " would undertake to cover a surface of vinous 
 liquid equal in extent to the area of the hall in which 
 we are assembled with mycoderma aceti in the space 
 of twenty-four hours. I have only to sow in various 
 
70 PASTEUR. 
 
 places the day before little spots hardly visible of the 
 mycodevjiia aceti." 
 
 This mycoderma aceti is, however, a peculiarly 
 difficiilt employe to deal with, for if supplied with an 
 insufficient allowance of alcohol he revenges himself 
 by consuming the acetic acid which he has been 
 engaged to produce, a mode of retaliation which pos- 
 sibly would commend itself to more exalted beings 
 placed under similar circumstances ! 
 
 As in the case of the alcoholic fermentation, so in 
 that of the vinegar or acetic fermentation, Pasteur 
 was neither the first to discover the process, nor the 
 first to see the living ferment, nor yet even the first 
 to connect the process with the life of the micro- 
 organism. The chemical change involved and the 
 part played by ox3^gen in the souring of wine 
 were already indicated by Lavoisier ; the process was 
 ascribed to catalysis, or contact action, by Berzelius in 
 1829. The familiar skin which forms on the surface 
 of the acetifying liquid was already named mycoderma 
 by Persoon in 1822, and the bacterial cells of which 
 this pellicle is composed were seen and actually 
 described under the name of ulvina aceti by Ktitzing 
 in 1837, who even suspected a connection between the 
 life of the organisms and the vinegar process. It will 
 be asked then, Where does Pasteur's discovery of the 
 acetic fermentation come in, when this discovery was 
 already a fait accompli at the time when Pasteur was 
 catching fish and drawing caricatures as a schoolboy 
 at Arbois ? 
 
 It is, however, one thing to dream of empire and 
 another thing to actually found one ; so it is one thing 
 to make a discovery, and often a very ditterent thing 
 to make the world accept it. 
 
STUDIES ON THE VINEGAR ORGANISM. 71 
 
 It is here that Pasteur stands out in such bold 
 rehef from so many other distinguished savants of 
 the century. Just as in connection with the alcohoUc 
 fermentation the pioneering work of Cagniard Latour 
 and Schwann was of such a character that it was practi- 
 cally effaced at one fell swoop by the edict of Liebig, so 
 here again the structure raised by Kiitzing was within 
 two years demolished by the same autocratic mandate. 
 
 But whilst the houses built by Cagniard Latour, 
 by Schwann, and by Kiitzing were only founded on 
 sand, and therefore destined to fall almost with the 
 first winter's blast, Pasteur was an architect who built 
 only on the solid rock of experiment, and the many 
 mansions which he has raised on the sites where lie 
 the shattered and almost forgotten ruins of his pre- 
 decessors have invariably withstood the Avhips and 
 scorns of time, becoming only more mellow with 
 advancing aofe. 
 
 It is in this connection that we realise that Pasteur 
 was not onl}^ a savant content to seek the truth and 
 find it, but that when he had in any matter succeeded 
 in the difficult task of convincing himself, he was 
 impelled Avith almost a fanatic's zeal to force his con- 
 viction on the Avorld, nor did he put up his SAvord 
 until every redoubt of unbelief had been taken, every 
 opponent converted or slain. Of this uncompromis- 
 ing spirit in his championship of AAdiat he believed to 
 be the truth he AA\as himself conscious, as is seen from 
 the folloAving passage, AA^hich occurs in the short reply 
 which he made at that supreme hour of his life Avhen, 
 on attaining the age of seventy, he enjoyed a triumph 
 such as had probably never been accorded before to a 
 man of science. 
 
72 PASTEUR. 
 
 " Si parfois j'ai trouble le calme de nos academies 
 par des discussions un peu vives, c'est que je defendais 
 passionnement la verite." 
 
 In perusing the terse summaries in which Pasteur's 
 labours on the acetic fermentation are recorded in 
 the Gomptes rendus, the reader cannot fail to be 
 struck with the breadth and scope of the view 
 which he takes of the phenomena before him, and 
 the manner in which he shows, by a pregnant word 
 here and there, the alertness of his mind to develop- 
 ments which even now are only partially realised. 
 Thus he points out that these organisms are not only 
 endowed with the power of producing acetic acid from 
 alcohol, but that they can impose the oxidising action 
 of the air on a multitude of organic substances, the 
 sugars, the organic acids, divers alcohols and albumin- 
 oids, giving rise in some cases to intermediate products 
 of which he had already detected some. Here, then, 
 we have indicated those beautiful transformations, 
 carried into execution many years later by Mr. Adrian 
 Brown, in which, by the agency of the acetic bacteria, 
 normal propylic alcohol was made to yield propionic 
 acid, (Z-glucose to give cZ-gluconic acid, mannitol to 
 produce la3vulose, and glycol, glycollic acid; whilst 
 methylic, isobutylic, and amylic alcohols, as well as 
 cane sugar, milk sugar, starch, and dulcite, remained 
 unaffected. He further points out the oxidising 
 action possessed in varying degrees by the family 
 of moulds, and thus shows the path subsequently 
 travelled along by Le Bel and many others in what 
 may be called the Tiioidd- combustion of racemoids, 
 as well as by Wehmer in the mould production of 
 oxalic and citric acids from carbohydrates. The 
 
STUDIES ON THE VINEGAR ORGANISM. 7S 
 
 same few pages indicate the necessity of reopening 
 the investigation of the process of nitrification, and 
 thus suggest the subsequent successful researches of 
 others in this field. 
 
 It was thus that by a long line of monumental 
 researches Pasteur had established the vitalistic 
 theory of fermentation, which may be expressed in 
 the words, No fermientation without organisms ; in 
 every fermentation a "particular organism. 
 
 It Avas hardly, however, to be expected that 
 Pasteur's opponents avouIcI allow this theorj^ to 
 triumph without striliing a last blow in defence of 
 the chemical or molecular vibration theory, which 
 had enjoyed such a long supremacy over the vital- 
 istic theories of thirty years before. 
 
 . Accordingly, in 1869 we find Liebig making a 
 lengthy communication to the Munich Academy on 
 fermentation and the source of muscular power. 
 
 These papers are of psychological rather than 
 scientific interest, the reader having little difficulty in 
 discerning that the great chemist, in the winter of his 
 brilliant career, is trying to retreat in good order be- 
 fore the irresistible advance of the younger man with 
 his improved Aveapons of precision, and to cloak his 
 defeat by endeavouring to shoAv that there is but 
 little real difference betAveen the tA\^o interpretations 
 put upon fermentation phenomena. 
 
 But toAA^ards the close there is a sudden change of 
 tone, for the author, doubtless so well satisfied Avith 
 his execution of the retrograde movement, has de- 
 ceived himself as to the real nature of his position, 
 and Avhen he should have been content to decently 
 bury an obsolete cause he becomes once more aggressive 
 
74 PASTEUR. 
 
 and contemptuous. He denies the activity of the 
 mycoderiiia aceti on the beechwood shavings used in 
 the German vinegar process, and calls to his assistance 
 in this weighty charge the ij^se dixit of a worthy 
 Munich vineo-ar manufacturer of the name of 
 Riemerschmied. 
 
 He challenges the accuracy of Pasteur's observa- 
 tion, that yeast can find its nitrogenous nutriment in 
 ammonia, and suggests that his results are due to 
 analytical inaccuracy. In support of his disbelief in 
 the assimilability of ammoniacal nitrogen he invokes 
 the assistance of that weak but blustering ally, vege- 
 table physiology, which at that time denied to all but 
 green plants the power of building up albuminoids 
 from ammonia. 
 
 But the scientific world had yet to learn how often 
 vegetable physiology would have to change its foliage 
 at the bidding of Pasteur and his successors. What 
 would Liebiff have said had he been told that the 
 study of these micro-organisms, for which he cannot 
 conceal that contempt which has been shared by so 
 many chemists even up to within the last few years, 
 would, Avithin the century, reveal the fact that car- 
 bonic acid can serve as a source of carbon to plants 
 without chlorophyll, and that albuminoids can be 
 synthesised from the free nitrogen of the air ? 
 
 Liebig's memoirs were exhumed from the obscurity 
 of the journals in which they had appeared, and were 
 in 1871 translated and published in the Annales de 
 Ghimie et de Physique. Pasteur was thus obliged to 
 take notice of them, and replied in the Coniptes-rendus 
 of the French Academy. 
 
 To us this reply appears a masterpiece of self- 
 
STUDIES ON THE VINEGAR ORGANISM. 75 
 
 restraint, written as it was after the great debacle 
 of 1870, the effect of which on Pasteur, who was 
 perhaps a yet greater patriot than savant, cannot be 
 reahsed by EngHshmen, who for generations have not 
 seen an eneni}^ on their own soil. 
 
 Terse and to the point, the few pages of Pasteur's 
 reply forni a most welcome contrast to the verbose 
 and unwieldy document of the Teutonic veteran. 
 Wasting no time on the sterile disquisition, of which 
 Liebig's paper is mainly composed, he hastens to fall 
 like a sledo^e hammer on the two direct nescatives with 
 which he had been challenged — viz. (1) the assimi- 
 lability of ammoniacal nitrogen by yeast, and (2) the 
 participation of the mycoderma aceti in the German 
 vinegar process. After reasserting the correctness of 
 his previous statements, he exclaims — 
 
 " Mais comment eclairer le public ? Comment 
 sortir de I'embarras que soulevent ces affirmations 
 contradictoires egalement honorables ? " 
 
 Then he has recourse to those tactics which he 
 found so effective in the case of his dispute with 
 Pouchet. He called upon Liebig to submit their 
 difference to the arbitration of the Academy, he 
 (Pasteur) undertaking to prepare several kilograms 
 of yeast from purely mineral materials, and also 
 to satisfy by ocular demonstration both Liebig and 
 the Academic Committee that the beechwood shav- 
 ings in Herr Riemerschmied's vinegar factory were 
 covered with growths of the mycoderma aceti which 
 Liebig had been unable to discover. 
 
 Liebig, however, did not accept the challenge 
 or renew the attack, and his submission had a touch 
 of melancholy about it which is apparent from the 
 
76 PASTEUR. 
 
 following letter, addressed during the ensuing year 
 (1872) to Duclaux, at that time an assistant of 
 Pasteur's : — 
 
 "I have often thought during my long and practical 
 career at my age (69 years) how much labour and how 
 many researches are necessary to understand a somewhat 
 complicated phenomenon. The greatest difficulty arises from 
 the fact that we are too much in the habit of attributing to 
 one cause that which is produced by several, and the majority 
 of our controversies thus arise. 1 should be very sorry if 
 M. Pasteur should take in bad part the remarks in my last 
 work on fermentation. He appears to have forgotten that 
 I only sought to sustain by facts a theory which I originated 
 now more than thirty years ago, and which he attacked. 
 I had, I believe, the right to defend it. There are very few 
 men whom I esteem more than M. Pasteur, and he can rest 
 assured that I did not dream of injuring his reputation, 
 which is so great and so justly acquired. I assigned a chemical 
 cause to a chemical phenomenon, and that is all that I 
 attempted to do," (Pasteur : " Histoire d'un Esprit," E. 
 Duclaux, Paris, 181)G.) 
 
CHAPTER VII. 
 
 THE DISEASES OF WINE. 
 
 The researches on the acetic fermentation which 
 we have just been considering open again a new 
 chapter in Pasteur's career, for whilst in his previous 
 investigations he had restricted himself to the 
 purely scientific aspects of the problems upon which 
 he was engaged, from henceforward we find the 
 practical application of scientific principles occupying 
 a large part of his attention. 
 
 The success which attended his efforts in thus 
 applying his discoveries, doubtless soon led to the 
 groAvth of a conviction within him that he Avas 
 entrusted Avith a great mission, Avhich embraced not 
 only the revelation of abstract truth, but also the 
 promotion of the material Avelfare both of his own 
 beloved country and of humanity at large. 
 
 Thus his excursion into practical matters in 
 connection with the manufacture of vinegar Avas at 
 once followed by his giving similar attention to 
 questions relating to the production of Avine. In 
 placing the vinegar process on a sound scientific 
 basis, Pasteur had obviously in reality broached the 
 subject of the " maladies des vins," for that the 
 souring of wine is one of the most Avidespread ills 
 to Avhich it is subject is surely Avell knoAvn to all. 
 What more natural, therefore, than that Pasteur 
 should conceive that those other and more 
 mysterious deteriorations Avhich Avines so frequently 
 undergo might receive a rational explanation by 
 
78 PASTEUR. 
 
 the application of those same methods which had 
 so effectually elucidated the vinegar process ? 
 
 He was not long in putting his ideas to the 
 test of scientific experience, and we find him installed 
 at Arbois in a hastily improvised laboratory, sub- 
 mitting to a minute microscopic examination wines 
 of all kinds, which had been gladly placed at his 
 disposal by many of the old comrades of his youth. 
 
 From the outset success followed his efforts, and 
 whenever a sample was presented to him defective in 
 some respect or other in taste, he discovered, mingled 
 with the yeast cells, a distinct microscopic form. 
 So skilful did he become in the detection of these 
 various germs, that he soon was able to predict the 
 particular flavour of a wine from an examination of 
 the sediment. In healthy wines, these foreign forms 
 were absent and yeast cells alone were discovered. 
 
 Although a number of difterent bacteria connected 
 with these several maladies of wine were described 
 and figured by Pasteur, it nmst not be supposed that 
 the mechanism of these processes was investigated 
 with anything like the completeness which character- 
 ised his researches on the acetification process. The 
 chemical changes taking place in the production of 
 wine are of a much more complex nature than in 
 the case of vinegar manufacture, and a large amount 
 of work is being done and still remains to be ac- 
 complished in connection with these more obscure 
 difficulties which attend the preparation of sound 
 wine. To Pasteur, however, is due the broad ex- 
 planation of these phenomena as dependent on 
 foreign organisms, and the further elaboration of 
 the subject is chiefly a matter of laborious detail. 
 
THE DISEASES OF WINE. 79 
 
 Pasteur, however, did not rest content with having 
 estabhshed the source of the disturbances which so 
 long had troubled the wine industry : he at once 
 proceeded to direct his attention to the possibility 
 of effectually guarding against them. The com- 
 mercial importance of this undertaking to the 
 country may be conceived when w^e remember that 
 at this time, 1867, a rough estimate of the capital 
 absorbed by the French wine industry is given as 
 500 millions of francs. 
 
 Pasteur's first experiments Avere made to discover, 
 if possible, a substance which, whilst inimical to 
 bacterial life, would not, when added to the wine, 
 impair its flavour and bouquet. Various antiseptics 
 were tried, but the results were not encouraging, and 
 Pasteur determined then to have recourse to heat. 
 He had, however, scruples in applying such severe 
 treatment to so delicate an article as wine, a preju- 
 dice which was shared later by manufacturers even 
 after Pasteur had demonstrated beyond all question 
 its beneficial effect upon wine. 
 
 He had, however, previously very carefully 
 studied the relationship of wine to oxygen, and he 
 did not anticipate that any evil would result, provided 
 that the wines w^ere only heated after they had 
 finished absorbing oxygen. 
 
 Moreover, he foresaw that a comparatively low 
 temperature — far below the boiling point — Avould 
 suffice, as from his experiments on spontaneous 
 generation he was well aware that the acid reaction 
 of the wine would facilitate the sterilisation, w^hilst he 
 had further reason to believe that it would not be 
 necessary to actually destroy all micro-organisms, and 
 
80 PASTEUR. 
 
 that it would be quite sufficient only to so paralyse 
 their activity as to prevent their inducing prejudicial 
 changes in the wine. 
 
 This simple process of partial sterilisation is now 
 generally known by his name as " Pasteurisation^' 
 and has already proved of enormous value to man, 
 having been employed with the greatest success in 
 connection with wine, beer, milk, cream, and other 
 food materials of a perishable nature, Avhilst in the 
 future there can be no doubt that it is destined to 
 become of ever increasing importance, and to largely 
 take the place of those chenucal preservatives or 
 antiseptics which at present are employed in such an 
 excessive and altogether reckless fashion. 
 
 Thus, Pasteur found that by heating wine for a 
 short time to a temperature of from 55 to 60 degs. 
 Centigrade it was effectually protected from subse- 
 quent deterioration, whilst it sutfered no alteration 
 in taste or bouquet. As mentioned above, how- 
 ever, wine growers were far from feeling convinced 
 that by venturing uj^on the adoption of this 
 method they would not be damaging their stock 
 to a much greater extent than by leaving them 
 to the operation of natural causes. But another 
 circumstance contributed not a little to the tardy 
 acceptance of Pasteur's discovery, and this was the 
 appearance about this time of that scourge of vine- 
 yards, the phylloxera, which led to the attention of 
 the whole wine world becoming centred upon this 
 disease, which subsequently wrought such terrible 
 havoc in some of the fairest and most favoured 
 provinces of France. 
 
 Convinced himself of the efficacy of his process for 
 
THE DISEASES OF WINE. 81 
 
 preserving wines, Pasteur was determined to also 
 convince the public, and after having privately 
 submitted samples of heated and unheated wine 
 respectively to the severe testing of skilled con- 
 noisseurs, and obtaining in each case favourable 
 reports, he approached the principal wine merchants 
 of Paris, and induced them to organise a committee 
 which should pronounce an impartial opinion upon 
 the relative merits of treated and untreated wines. 
 This committee was formed without difficulty, met 
 in November, 1865, at the Ecole Normale, where, after 
 the most searching tests which could be devised and 
 
 o 
 
 apf)lied, it was unanimously stated that if any differ- 
 ence did exist between the heated and the unheated 
 wines it was so insignificant as to be practically im- 
 perceptible. 
 
 Thus one of the most im23ortant economical prob- 
 lems of the day was solved, solved, as Dumas so 
 aptly described it, not through chance experiments 
 but by means of researches directed by a profound 
 knowledge of the laws of nature, and aided by an 
 exquisite appreciation of the methods which science 
 possesses for their revelation. 
 
 Pasteur was attacked somewhat virulently more 
 than once on the ground that this idea of heating 
 wines was not original, and he was accused amongst 
 other things of having resuscitated, without aclaiow- 
 ledgment, some experiments made long ago by Appert. 
 It, is, however, only just to Pasteur to say that he 
 was not aware of these investigations when he carried 
 out his experiments, and that as soon as his attention 
 was directed to them, he at once publicly acknow- 
 ledged and described them in a memoir which he 
 communicated to the Academy of Sciences. In this 
 
 F 
 
82 PASTEUR. 
 
 he mentions how Appert had sent bottles of Beaime 
 from Havre to Saint Dominique, the bottled wine 
 having been previously heated in a water-bath to 
 70 degs. Centigrade, and that on its return to 
 Havre he compared two bottles of this wine with 
 some which had not been heated. Appert apparently 
 laid great stress upon the fact that the heated bottles 
 were markedly superior to the others, and had, more- 
 over, suffered no damage from the process either in 
 taste or bouquet. 
 
 It was, moreover, urged that this heating of wine 
 had for some time past been carried on extensively at 
 Meze in the South of France. In order to meet 
 this attack, Pasteur went to Meze and inspected the 
 process in vogue there ; he returned triumphant, re- 
 marking " that they do certainly heat their wine at 
 Meze, but it is to age it more rapidly. To bring this 
 about they heat it exposed to the air for a long time, 
 in such fashion that the taste is altered, and some- 
 times unpleasantly so, and immediate steps have to 
 be taken to correct it ; this clumsy proceeding shows 
 that the merchants of Meze are not too well up in 
 what they are doing, and have not read my book. 
 It would be to their interest to do so, for I supply the 
 theory of their practice. Meanwhile, however, what 
 is there in common between this long and perilous 
 heating of wine in the presence of air and the rapid 
 heating to 50 degs. Centigrade in the absence of air 
 which I recommend ? Far from having received any 
 suggestions from the Meze methods, I rejoice that I 
 was ignorant of them. They might have deterred me 
 from employing heat, for whilst I aimed at pro- 
 ducing no change in taste, their one object is to secure 
 such an altcratioii." 
 
CHAPTER VIII. 
 
 RE.SEAPtCHES OX SILKWORM DISEASES. 
 
 During the progress of his researches on fermenta- 
 tion, Pasteur had exchanged his official appointment 
 of Director of Scientific Studies in the Ecole Normale 
 for the Professorship of Geology and Chemistry at the 
 Ecole des Beaux- Arts, which post he held from the 
 year 1863 to 1867. 
 
 It was during the latter part of his tenure of this 
 office that he entered upon an entirely novel line of 
 investigation, which, although belonging in point of 
 time to what may be described as the " fermentation 
 period " of his researches — for the Etudes sur la Biere 
 followed later — yet had nothing whatever to do with 
 it, but was, on the other hand, a sort of prophetic 
 incursion into that region of viruses and vaccines 
 where later the climax of his fame was to be 
 reached. 
 
 At this time a portion of France was experiencing 
 one of those waves of industrial calamity Avhich 
 periodically overwhelm communities, and cause dis- 
 tress and suffering hardly less acute than those which 
 are consequent on war. The helplessness even of 
 modern civilisation in stemming these disasters must 
 have impressed all who have Avitnessed such indus- 
 trial disturbances as the phylloxera, the potato disease, 
 or the rinderpest, which are the nineteenth-century 
 F 2 
 
84 PASTEUR. 
 
 counterparts of some of the plagues of Egypt. It was 
 with a great national calamity like any one of these 
 that Pasteur was to be called upon to cope single- 
 handed, and the eyes of the world were naturally fixed 
 — in many cases, no doubt, with scepticism and dis- 
 trust — on this new Bellerophon and his winged 
 Pegasus of modern science. 
 
 The monster which he was challenged to overcome 
 and destroy with the resources of science was a disease 
 called " jyebrinej' which, having already attacked the 
 silkAvorms in 1849, had by this time so crippled the 
 silk industries of the country that the annual revenue 
 to the State from this source had been reduced in the 
 course of twelve years from 130,000,000 to 8,000,000 
 francs. The value of the cocoons produced, in normal 
 years reaching more than 100,000,000 francs, fell in 
 the years 1863 and 1864 to 34,000,000 francs. From 
 this last figure 10,000,000 must be deducted, this 
 sum representing the extra cost of purchasing foreign 
 "graine""^ instead of the cultivators raising it them- 
 selves. 
 
 Some idea of the epidemic proportions which this 
 disease had assumed amongst all European countries 
 may be gathered from the fact that whilst in the year 
 1853 France was able to import healthy silkworms' 
 eggs from Spain and Italy, ten years later there was 
 not a corner of Europe which was free from the disease, 
 and recourse had to be had to Japan, where alone non- 
 infected eggs were procurable. 
 
 A silkworm cultivator, writing already in 1862, 
 gives a graphic picture of the distress which the 
 
 * A technical expression for the eggs of the silk-moth. 
 
RESEARCHES OX SILKWORM DISEASES. 85 
 
 disease had brought about m his district : — '•' The 
 traveller who some fifteen years ago traversed the 
 Cevennes mountains and retraces his steps to-day, 
 would be astonished and deeply moved by the changes 
 of all descriptions which have taken place in so short 
 a space of time in the district. 
 
 " Formerly he saw on the slopes of the hills active 
 and sturdy men busy quarrying the rock, building 
 solidly constructed walls out of the debris, destined 
 to support fertile soil prepared with infinite labour, 
 and carried thus to the summit of the hills in care- 
 fully laid-out terraces, upon which mulberr}^ trees 
 Avere planted. These men, despite the fatigues of 
 such hard work, were happy and contented, for 
 comfort surrounded their domestic hearth. 
 
 " To-day these plantations of mulberry trees are 
 completely abandoned ; ' the golden tree ' no longer 
 enriches the country, and there, faces formerly 
 radiant, are now melancholy and sad ; where before 
 plenty reigned, now misery and poverty prevail." 
 
 So acute a stage had matters reached in the year 
 1865 that a great petition was forwarded to the Senate 
 with 3,600 signatures attached of the mayors, muni- 
 cipal councillors, and landed proprietors belonging to 
 the silkworm districts, urging upon the Government 
 the appointment of a commission to inquire into 
 the disease, with a view to remedial measures being- 
 adopted, so that the silk industry might be saved, if 
 possible, from the bankruptcy which was staring it 
 in the face. 
 
 Already in 1857 the Government had mstructed 
 Dumas to visit the silkworm districts and report 
 upon the character and distribution of the disease. 
 
86 PASTEUR. 
 
 The vaguest ideas were current as to the conditions 
 controlHng its dissemination. Thus many were of 
 opinion that the mulberry trees were the source of 
 the evil, and the practice had arisen of treating the 
 latter with sulphur; others, again, attributed the plague 
 to atmospheric conditions, and had proposed the use 
 of disinfectants such as chlorine or carbolic acid, 
 Some cultivators had even suggested making the 
 worms take rum or absinthe, and then a disinfectant 
 in the shape of a dose of nitrate of silver or creasote. 
 Dumas, however, examined the mulberry trees and 
 could find nothing to justify their being held 
 responsible for the calamity ; the state of the air in 
 the marjaaneries, or breeding rooms, he also 
 regarded as incapable of solving the mystery. He 
 succeeded, however, in indicating the external signs 
 of disease in the affected worms, but he was quite 
 unable to suggest any remedial measures. 
 
 When the nomination of a commission of inquiry 
 was forced upon the Government they once more 
 approached Dumas ; his previous knowledge of the sub- 
 ject, his great scientific reputation, and his well-kno^vn 
 sympathy with the widespread distress produced by 
 the disease, combining to render his presidency of the 
 commission satisfactory to all parties. 
 
 With admirable sagacity, Dumas, instead of turning 
 to some distinguished zoologist, entomologist, or other 
 authority learned in the ecdyses and metamorphoses 
 of the insecta in general and of the lepidoptera in par- 
 ticular, at once singled out Pasteur as the man who 
 of all others was most capable of being entrusted with 
 the difficult task of searching out the hidden mysteries 
 of this disastrous silkworm disease. 
 
RESEARCHES ON SIUsWOIlM DISEASES. <S7 
 
 Pasteur was, however, loth to leave his investiga- 
 tions on fermentation, which had now begun to open 
 11 J) vist,as of work the interest and importance of 
 which seemed woll-ni^-h inexhaustible. To abandon 
 a field of research which he had conquered after so 
 much toil and trouble, and to embark upon a fresh 
 voyage of discovery the issue of which was highly 
 doubtful, and upon which years of valuable time 
 might bo vainly expended, was indeed an enormous 
 sacrifice to demand of any scientific man. 
 
 " Considerez je vous prie," urged Pasteur in re- 
 sponse to Dumas' pressing recpiest, "que je n'ai 
 jamais toucho a un ver a soie." 
 
 "So nuich the better," replied Dumas; "for just 
 by knowing nothing of the subject you will import 
 no ideas but those which you derive from your own 
 observations." 
 
 l)Ut coupled with liis reluctance to interrupt the 
 work upon which his whole thoughts were at this 
 time concentrated, Pasteur was himself diffident about 
 his powers of carrying such an undertaking to a 
 successful issue. 
 
 Dumas was, however, obdurate in his insistence 
 that Pasteur should devote himself to the question, 
 and at length persuaded him to overcome his scruples 
 and accept the task entrusted to him. Thus Pasteur, 
 who had never made a dissection in his life — who had 
 never seen or handled a silkworm, and knew nothing 
 of physiology — suddenly found himself precipitated 
 headlong, as it were, into an investigation the very 
 importance and publicity of which would in themselves 
 have been sufficient to deter other men from running 
 the risk of failure. 
 
88 PASTEUR. 
 
 M. Duclaux describes how, after Pasteur had 
 finally accepted the mission entrusted to him, he, 
 with characteristic enthusiasm, endeavoured at once 
 to obtain some knowledge of the larvK of insects in 
 general by w^atching the dissection of worms, etc. He 
 attends meetings of the Imperial Commission on Silk 
 Culture, from which, however, he returned more dis- 
 couraged than enHghtened ; he rapidly peruses some 
 of the latest publications on the subject, and leaves 
 for Alais on June 6th, 1865, accompanied b}^ Duclaux, 
 Gernez, Raulin and Maillot, all assistants of his at 
 the Ecole Normale, hardly three weeks having elapsed 
 since he first wrote placing himself at the disposition 
 of Dumas. 
 
 M. Gernez tells us how, on his arrival at Alais, 
 Pasteur at once made himself accessible to one and 
 all. Full of consideration, he would thoughtfully 
 listen to everything, taking, however, little part in 
 any ordinary conversation, but full of interest and life 
 immediately any scientific subject was discussed. 
 His simple and incisive language displayed his clear 
 grasp of the question, whilst the spirit and animation 
 of his address, combined Avith the restraint imposed 
 by a rigid adherence to strictly logical reasoning, 
 rendered him a most eloquent and impressive 
 speaker. 
 
 The outward and visible signs ot" this pehrine are 
 variously exhibited, sometimes at the time of hatch- 
 ing already, a mass of graine or eggs proves sterile, or 
 a great mortality takes place amongst the worms 
 during the first few days of their existence. 
 
 Sometimes all goes well until the first moult, 
 when many worms begin to eat very little and become 
 
RESEARCHES ON SILKWORM DISEASES. 89 
 
 blackish in appearance, and a number die off. In 
 some cases, aL'-ain, no trace of disease is visible until 
 the third or even the fourth moult, but frequently, 
 instead of assuming the proper white tint, the skins 
 remain yellow, and the worms eat less and less and 
 die off, or their bodies l)ecome gradually covered with 
 black marks. Frequently the silkworm breeder is 
 deprived of every single insect before the chrysalis 
 stage has been reached. 
 
 An even more tragic exhibition of the disease, 
 however, is to be found in those cases where nothing 
 has occurred to interrupt the normal succession of 
 stages in the life of the worms, and the latter have 
 arrived at the period characterised by voracious 
 feeding which precedes the chrysalis condition. It is 
 at this period that in the silkworm chambers the 
 peculiar noise of the mandibles busy at work, 
 resemblini*' the sound of rain fallino;' on the leaves of 
 trees, rejoices the heart of the proprietor, for he 
 knows that the time is now approaching when la 
 hruyere* will be covered with silk of the colour of 
 gold and silver. 
 
 The dismay can be pictured when an inspection of 
 the silk won ri tables suddenly at this period reveals 
 the fact that numbers of these full-Gfrown worms are 
 failing to oat, and that numbers are either dead or 
 dying. Pasteur has himself vividly described this 
 tragedy in the following sentences : — " After having 
 bestowed his time and his labour upon his dear 
 hetail, dispensed his leaves, paid his workpeople, the 
 
 * Branches of brushwood in which the maturo caterpillars ascend 
 to spin their cocoons. 
 
90 PASTEUR. 
 
 unfortunate breeder gathers nothing but putrefying 
 bodies. Formerly the period of collecting the cocoons 
 was a season of fetes and rejoicings. In spite of the 
 labours of the last days, when the appetite of the 
 worms cannot be appeased except at the expense of 
 attention which knows no pause either day or night, 
 joyous songs resound throughout the country, on the 
 trees where the gathering of the leaves ■ is going on, 
 near the tables where the precious insect, the body 
 full of silk, is hastily mounting to the hruyere, there 
 to construct its golden prison. A single incident will 
 convey an impression of the im23ortant part which 
 the harvesting of the precious textile plays in the life 
 of the people, in these districts : The payments of the 
 whole year, all the arrangements of business turn 
 around the completion of the silkworm culture. This 
 custom, so ancient and respected, is to-day nothing 
 more than a memory." 
 
 As has before been mentioned, numerous works 
 and pamphlets had been published, and quite a mass 
 of literature already existed upon the subject when 
 Pasteur entered the field. 
 
 A great number of careful observations had been 
 made by various observers. Thus microscopic cor- 
 puscles had been seen in the diseased silkworms by 
 Guerin-Meneville ; their pathological import had been 
 suspected by Cornalia ; their abundant presence in all 
 the diseased larvcC and moths had been observed by 
 Lebert andFrey; whilst Osimo of Padua had even 
 found them in the eggs. Vittadini, moreover, in 1859, 
 had suggested that these eggs should be submitted to 
 a microscopic examination to ensure that only healthy 
 ones should be preserved.. 
 
IIESEARCHES ON SILKWORM DISEASES. 91 
 
 Various endeavours at isolation and other nietliods 
 of compassing the plague had been resorted to, but so 
 far nothing had availed, and the disease was as ram- 
 pant as ever when Pasteur and his assistants took up 
 their abode in the little house in the environs of Alais 
 and started the culture of silkworms. 
 
 Pasteur's first efforts were directed to searching out 
 the corpuscles which had figured so prominently in the 
 reports of his predecessors in this field of inquiry, and 
 he had but little difficulty in discovering them, for all 
 the silkworm nurseries in the neighbourhood were in- 
 fected with disease. A few hours after his arrival he 
 was able to show the famous corpuscles to many 
 members of the Agricultural Society who had never 
 before set eyes on them. An examination of sickly 
 worms and moths revealed the presence of thousands 
 of these same corpuscles ; all the so-called 'pehrine 
 worms appeared to be invaded by masses of these 
 little oval, luminous bodies. 
 
 The question Avas, What connection had these 
 corpuscles with the disease with which the worms were 
 afflicted ? And now the work beo-an in real earnest. 
 Pasteur's plan was to initiate all the experiments 
 himself, carrying th^m out personally even in the 
 minutest details, only calling in his assistants to 
 repeat them and control their accuracy. His energy 
 was boundless ; he would frequently rise at live in 
 the morning so as to be present at the first feeding of 
 the silkworms, and not retire to rest until eleven, 
 after their last meal. At the end of his long day's 
 toil, instead of taking his much-needed repose, he 
 would commence on the mass of correspondence of 
 all kinds with which he was inundated, and which 
 
92 PASTEUR. 
 
 more frequently than not involved replies to hostile 
 critics. Theories and ideas poured in upon him from 
 France and all parts of the world; and in order to 
 clear the wa}^ for work, he was obliged to sift care- 
 fully and place on one side those which appeared to 
 have any semblance of value, whilst he felt it in- 
 cumbent on him to test with the utmost care and 
 accuracy before pronouncing an opinion upon methods 
 which were stated to be capable of " infallibly " curing 
 the disease. The amount of work which this in- 
 volved is more easily imagined than described. Often 
 of an evening, M. Gernez tells us, Pasteur, broken 
 down with fatigue and worry, would exclaim to his 
 assistants : " Helas ! nous n'avanyons pas ! " 
 
 This was in 1S66, and Madame Pasteur determined 
 to leave Paris and come with her two daughters to 
 Alais, to help to cheer and help him during this 
 terribly trying and anxious time. Unfortunately, 
 before reaching Alais the elder of the two children 
 developed typhoid fever at the house of one of 
 Madame Pasteur's sisters. Having already lost their 
 eldest child from the same disease, the anxiety of the 
 parents can be readily conceived, and for five weeks 
 Pasteur, heroically abstaining "from forsaking his 
 work, Avas a prey to the most acute mental suffering. 
 At length, yielding to the entreaties of his assistants, 
 he left Gernez in charge, and joined his wife in time 
 only to spend a few days with his child before a 
 relapse brought about a fatal termination of the 
 malady. Pasteur's grief was pathetic to witness, for 
 he was a most devoted father: but he returned to 
 Alais with his wife and little daughter, and patiently 
 and bravely took up his work once more. 
 
RESEARCHES ON SILKWORM DISEASES. 93 
 
 We have seen that the first problem awaiting 
 sohition was to ascertain the connection, if any, which 
 the bright oval bodies or corpuscles already referred 
 to, found in the bodies of afEicted silkworms, had 
 with the disease of pehrine. 
 
 All the previously ascertained facts concerning 
 them w^ere confirmed by Pasteur, but nothing in the 
 whole course of this most interesting inquiry is more 
 remarkable than that Pasteur, who in his fermenta- 
 tion experiments had been guided so successfully 
 by the conviction that the living organism was the 
 cause of the chemical process, should have failed for 
 so long a time, in spite of his intimate contact with 
 the disease in all its various phases, to recognise that 
 these living corpuscles were the real materies morbi 
 of the pebrine. 
 
 For more than two years Pasteur held the opinion 
 that these corpuscles were only the consequence of, 
 or the visible witnesses, as it were, to a disease which 
 had already invaded the worm. It was only tow^ards 
 the close of the year 1867 that he recognised that 
 these living particles were parasitic to the worm and 
 the fans et origo of the disease. The history of 
 Pasteur's misconception in this important matter is 
 very interesting and extremely simple. 
 
 Soon after he had commenced his studies at Alais, 
 he came across two sets of silkworm cultures, one of 
 which had apparently succeeded very well, so much so 
 that the proprietor had already decided to preserve all 
 the chrysalides for the future supply of eggs, considering 
 them perfectly healthy, whilst the other culture had 
 a bad appearance and showed unmistakable signs of 
 being iAfected. iSTow Pasteur examined chrysalides and 
 
94 PASTEUR. 
 
 moths from the culture which had raised such buoyant 
 hopes in the heart of the proprietor, and discovered 
 masses of corpuscles ; in worms taken from the un- 
 promising nursery he, on the contrary, only discovered 
 a few here and there. Nor Avas this an isolated 
 observation, for Pasteur confirmed it over and over 
 again. How was this to be interpreted ? To all ap- 
 pearance the presence of corpuscles and disease were 
 two distinct phenomena. Worms could seemingly be 
 perfectly healthy and yet give rise to chrysalides 
 swarming with corpuscles, whilst worms could be 
 severely and visibly afflicted with disease and yet 
 possess hardly one of these suspicious particles. 
 
 Pasteur, before venturing to draw a definite con- 
 clusion from these most puzzling and to all appear- 
 ances contradictory observations, waited to see what 
 would be the condition of the chrysalides derived from 
 the unpromising but comparatively corpuscle-free 
 nursery. He studied these chrysalides day by day, 
 and he found that in proportion as they developed 
 the corpuscles became more and more abundantly 
 present, whilst finally not a single moth was with- 
 out them, and they were, moreover, demonstrable in 
 great numbers. 
 
 Another most striking observation contributed to 
 conceal the real character of the corpuscles from 
 Pasteur at this time. With the object of ascertaining 
 what part, if any, was played by the dust and refuse 
 in the infected silkworm nurseries, he collected and 
 microscopically examined debris and rubbish Avhich 
 had been left lying from the previous year's cultures, 
 for at this time the incredibly dirty custom prevailed 
 of leaving the nurseries untouched, and only cleaning 
 
RESEARCHES ON SILKWORM DISEASES. 95 
 
 them up a tew weeks before the new season's work 
 cornnienced. 
 
 Pasteur was amazed at the enormous numbers ot 
 the corpuscles which he found mixed up with this 
 dust, looking as distinct and as well defined as he was 
 accustomed to see them in the tissues of the worms 
 themselves. In order to find out if this dust served 
 to spread the disease, Pasteur took some perfectly 
 healthy worms and fed them on leaves sprinkled over 
 with it. The mortality which followed this dust re- 
 past was very great, but on examining the dead worms 
 he was immensely surprised to find no corpuscles. 
 Thus again Pasteur was confirmed in his idea that the 
 corpuscles were not the agents but rather the results 
 o\^ pehrine. 
 
 Later observations, however, enlightened him upon 
 this as on other perplexing difficulties, for he dis- 
 covered that these corpuscles lose their pathogenic 
 or disease-producing power when they have been 
 kept, as the above had been, for a long time in a dry 
 condition in contact with air. The corpuscles he saw 
 in the dust were the corpuscles of pehrine, but they 
 were dead and incapable of provoking disease. The 
 death of the worms, he discovered later, was due to 
 another disease altogether, to which we shall have to 
 refer presently. It was in the spring of the year 1868 
 that Pasteur found conclusively that it was possible 
 to infect worms with pebrine by feeding them with 
 freshly collected dust containing living corpuscles. 
 
 Now we come to the point where Pasteur took the 
 wrong turning^, as it were. He first concluded that in 
 both the nurseries above referred to the same disease 
 had infected the worms, and that the only difference 
 
96 PASTEUR. 
 
 in the two cases was its greater severity in the one 
 than in the other. He secondly was led, as we have 
 before mentioned, to believe that the corpuscles Avere 
 only a delicate means of diagnosing the existence of 
 disease, but were not themselves the cause of the 
 malady. Nevertheless, his observations of the ap- 
 parent preference exhibited by the corpuscles for 
 establishing themselves in the chrysalis and moth 
 staofe of the worm's life, caused him to recommend 
 the wise plan of microscopically examining chrysa- 
 lides and moths for corpuscles with a view to their 
 preservation or destruction, as the case might be, 
 and so avoiding the employment in the subsequent 
 year of infected graine, and the consequent waste of 
 labour and money in rearing diseased worms. 
 
 We know now, for Pasteur himself has shown us, 
 that he was wrong in his conclusions, that the cor- 
 puscles are the cause and not the consequence of 
 pebrine, that in the sickly worms where he failed to 
 find them, or only in small numbers, the worms were 
 suffering at the time from a totally distinct disease, 
 although later falling victims to pebrine as well. 
 
 But Pasteur's erroneous reasoning led him also to 
 make mistakes in his method of examining the moths 
 for the presence of corpuscles. Convinced that these 
 particles were the later signs of a pre-existing disease, 
 he considered that they would be omnipresent in the 
 insect's body, and hence he pronounced a moth in- 
 fected or not infected according as he discovered 
 corpuscles in a small portion of the skin of the 
 abdomen. Had he been impressed with the parasitic 
 nature of the corpuscles he would have realised, as he 
 did later, that such an examination was not sufficient, 
 
RESEARCHES ON SILKWORM DISEASES. 97 
 
 that the corpuscles might be absent in some organs 
 and present in others. 
 
 Thus his method of endeavouring to insure only 
 the eggs of healthy moths being employed sometimes 
 succeeded and, naturally, sometimes failed. It was only 
 when he adopted the plan of pounding the body of 
 the moth in a mortar with a little water and examin- 
 ing a drop of the emulsion under the microscope, that 
 he was able to pronounce with certainty upon the pre- 
 sence or absence of corpuscles, and hence presence or 
 absence of disease in the insect, and the consequent 
 value to be attached to its eggs. 
 
 When Pasteur had at last succeeded in unravelling 
 the mystery of pehrine, his endeavours were at once 
 directed to persuading silkworm proprietors to adopt 
 the method just mentioned for the separation of good 
 from bad graine, and foreseeing that the use of the 
 microscope might prove an impediment to its being 
 employed by these good people, he anticipates their 
 objections by saying: "If you tell me that you are 
 afraid of the microscope and that its management 
 does not appear easy, know that I have a little girl 
 but eight years old who makes very good use of it." 
 
 The systematic examination of the moths recom- 
 mended by Pasteur is now universally adopted, and 
 hundreds of women and girls may be seen every year 
 at the period of " grainage " pounding up moths, 
 making microscopic examinations, and sorting the 
 eggs from the healthy and unhealthy moths respec- 
 tively. 
 
 Once convinced of the parasitic character of 
 pehrine, Pasteur proceeds to make elaborate investi- 
 gations showing its communicabihty, whilst he also 
 
 G 
 
98 PASTEUR. 
 
 indicates the precautions which, should be observed 
 to keep it within bounds and circumvent its dissemi- 
 nation. He had already shown how the dust of 
 infected nurseries was capable of propagating disease, 
 and he impresses upon the proprietors the necessity 
 of cleanliness, of observing far greater precautions 
 than had hitherto been customary, to insure the 
 requisite hygienic conditions for the protection of 
 the worms from disease. He demonstrates how one 
 worm in an infected litter can infect another by 
 crawling over its body and inflicting small wounds 
 with its feet, the latter being shown in many cases to 
 have the fatal corpuscles attached, collected there by 
 the worm in the course of its wanderings amongst its 
 dead companions or over the excrements of iiebvine 
 victims. 
 
 He presents the silkworm proprietors with an 
 easy method of distinguishing healthy from' infected 
 eggs, which while saving the trouble and expense of 
 rearing sickly worms, would also materially assist in 
 diminishing the proportions of the epidemic by 
 banishing bad graine and employing only that 
 certified as free from disease. 
 
 The victory seemed complete, the triumph certain, 
 and Pasteur awaited with confidence the result of the 
 cultures with the graine which be had collected and 
 certified as pure by his method the previous year. 
 His intense disappointment and mortification may 
 be imagined when he received along with letters 
 testifying to the complete success of the cultures 
 raised from his graine, numerous complaints of 
 silkworm disease. He became more and more 
 depressed, but did not communicate his fears and 
 
RESEARCHES ON SILKWORM DISEASES. 99 
 
 anxiety to his assistants until one day, coming into 
 the laboratory almost with tears in his eyes, he sank 
 disconsolately into a chair and exclaimed, " II n'y a 
 rien de fait ; il y a deux maladies ! " 
 
 Yes, there were indeed two silkworm diseases, and 
 it was their superposition which was largely respon- 
 sible for the circumstance that Pasteur had so tardily 
 arrived at the truth with regard to the corpuscular 
 cause of pehrine. 
 
 It will be remembered how Pasteur had come 
 across this other disease already on several occasions, 
 but he had, in connnon with many other authorities, 
 regarded it as but a part, a different symptom, of this 
 same pebrine upon the elucidation of which he had 
 concentrated all his efforts. 
 
 He tells us frankly himself how, up to the year 
 1867, he had put this interpretation upon the facts 
 which he had observed, which, he goes on to say, "je 
 considcre aujourd'hui comme tout-a-fait erronee . . . le 
 progres de mes etudes vint Jeter do nouvelles lumieres 
 sur le sujet, et etendre le cercle des difficultes a 
 vaincre ot des experiences a tenter." 
 
 From this time onwards he realised that the cause 
 of the disastrous condition to which the silkworm 
 industry had been reduced was attributable not to 
 one disease alone, but also to a second, totally distinct 
 and independent from the other, a disease the appear- 
 ance of which was familiar enough to silkworm cul- 
 tivators, although its origin was as great a mystery 
 as had been that of pebrine. 
 
 This disease was known as the maladie des viorts- 
 blancs, morts-flats, or more commonly called la 
 flacherie. 
 G 2 
 
100 PASTEUR. 
 
 This disease generally attacks silkworms after they 
 have completed their fourth moult. To all outward 
 appearance the worms are in excellent condition, but 
 their movements are languid, and their death follows 
 quickly, their bodies becoming black after an interval 
 of from twenty-four to forty-eight hours. If they 
 manage to creep on to the twigs they remain for 
 days before they complete la onontee, and so familiar 
 is this condition of the worms to the cultivator that 
 an old custom prevails of burning incense, or thyme, 
 or perfumes, or raising the temperature of the nursery 
 to rouse them from this state of lethargy. 
 
 Pasteur points out how important it is that this 
 phenomenon should receive careful attention from 
 silkAvorm cultivators, and that the resulting chr3'salides 
 should be destroyed and not preserved for purposes of 
 grainage for the following year ; unless this precau- 
 tion is observed the nurseries will be decimated by 
 flacherie. 
 
 Careful investigation convinced Pasteur that this 
 disease is due essentially to a disturbance in the 
 digestive functions of the worm; this disturbance he 
 moreover discovered to be akin to a process of 
 fermentation set up by particular vibrios or bacteria, 
 which he describes as vibrions de la flacherie, and 
 by a series of skilful experiments he demonstrates 
 beyond question the contagious character of the 
 disease. His remarks on this micro-organism and 
 its appearance are of great interest in connection 
 with the history of the discovery of the hardy or 
 spore form of bacteria in disease. That he really 
 observed spores in these bacilli we know from a 
 remark which he makes in a foot-note, where he 
 
RESEARCHES ON SILKWORM DISEASES. 101 
 
 points out how the supposed identity of 'pdbrine with 
 flacherie by many observers may have been materially 
 assisted by the similarity in appearance of the pehrine 
 corpuscles "aveclcs potits corps brillants quo Ton voit 
 souvent dans I'interieur des vibrions." 
 
 Again, that this micro-organism was endowed 
 with the power of existing in this spore and hardy 
 form, we have evidence from the fact that worms 
 succumbed to Jiacherie from swallowing infected dust 
 more than a year old, for we know now that the 
 fragile or rod form could not have survived this 
 length of time under such conditions, but that in 
 the spore form a micro-organism can retain its 
 vitality and virulence for long periods of time under 
 apparently most trying and disadvantageous circum- 
 stances. J^isteur was, therefore, the iirst to discover 
 the spore form in a pathogenic or disease-producing 
 micro-organism. 
 
 Whilst predisposition, such as eggs derived 
 from chrysalides infected y^'iih flacherie, plays an im- 
 portant part in determining the appearance of this 
 disease, yet its occurrence may often follow from 
 accident due to inattention to details of manaofement. 
 Thus overcrowding in the litters, too high a tem- 
 perature in the nurseries, bad ventilation, the use of 
 wet leaves, are all fertile sources of flacherie, inas- 
 much as they affect the vitality and health of the 
 worms. As long as the worms are vigorous, these 
 vibrios or microscopic organisms, which are derived 
 from the mulberry leaves themselves, are kept in 
 abeyance by the secretions of the intestine, but if 
 adverse circumstances arise, depressing the vitality of 
 the insects, the digestive functions become disorganised, 
 
102 PASTEUR. 
 
 the vibrios get the upper hand, and the symptoms of 
 flacherie declare themselves. 
 
 One circumstance which promotes /^acAeHe is the 
 use of mulberry leaves from trees which are regularly 
 pruned each year. Such leaves are larger and coarser 
 and more indigestible than those gathered from trees 
 allowed to crrow wild. 
 
 The custom of pruning the trees is not surprising, 
 for, whereas it requires one man per day to gather 
 sufficient leaves from a pruned tree, to provide food to 
 satisf}^ the inordinate hunger of the worms just before 
 the chrysalis state is reached for a nursery supposed 
 CO yield 100 kilogrammes of cocoons, it involves the 
 labour of foiu' men per day to collect sufficient food 
 material at this busy time from unpruned or wild 
 trees. 
 
 Of so much importance is the character of the 
 mulberry leaf in the feeding of worms, that it is 
 recommended to start the cultures as early as pos- 
 sible, so that the leaves are younger and more diges- 
 tible at the critical and last stage of the worm's life. 
 An enthusiastic valet attached to the person of 
 Henry IV. of France was ennobled and appointed 
 controller of commerce and of mulberry trees in 
 France by his master, on account of the zeal and 
 intelligence which he displayed in the culture of silk- 
 worms. Many of the observations on silkworm 
 culture made by this Lafifemas on the advantages of 
 cultivating the mulberry tree in the centre and north 
 of France, in a work published in 1604, are, Pasteur 
 points out, full of wise advice which silkworm pro- 
 prietors would do well to follow at the present day. 
 Thus, amongst other things, cleanliness is insisted 
 
RESEARCHES OX SILKWORM DISEASES. 103 
 
 upon, too high temperatures are condemned, and the 
 use of coarse and wet leaves proscribed. 
 
 In studying this second silkworm disease, Pasteur 
 was brouo'ht in contact for the first time with a 
 number of phenomena akin to those which obtain 
 in the infectious diseases of man and the higher 
 animals. It was in investigating this bacterial disease 
 oi flacherie, that he acquired that great store of ideas 
 which he afterwards so successfully deployed into line 
 in his brilliant attack upon those subtle maladies 
 which absorbed the later years of his life. 
 
 That he himself was deeply conscious of the 
 educational value Avhich these researches on pebrine 
 and flacherie had possessed for him, is shown by the 
 fact that in after years, when young medical men were 
 aspiring to undertake researches in his renowned 
 laboratory at the Institute bearing his name, he never 
 failed to say to them, " Lisez les etudes sur les vers a 
 sole ; cela sera, je crois, une bonne preparation aux 
 travaux que nous allons entreprendre." 
 
 Meanwhile his arduous toil and brilliant investiga- 
 tions had not passed without recognition from foreign 
 countries. In the year 1868 the honorary degree of 
 Doctor of Medicine was conferred upon him by the 
 University of Bonn ; the prize of 5,000 florins, offered 
 by the Austrian Government in 1868 to whoever 
 should succeed in discoverino- the best means of com- 
 passing the disease of pebrine in silkworms was 
 awarded to Pasteur also in this year ; whilst in 1869 
 he was elected a foreign member of the Eoyal Society 
 of London. In the market-place at Alais a fine 
 statue of Pasteur has recently (1896) been erected, in 
 which he is represented standing, gazing fixedly at a 
 
104 PASTEUR. 
 
 sprig of mulberry covered with cocoons, which he is 
 holding in his left hand ; at his feet is a young girl in 
 a graceful attitude handing him other cocoons, whilst 
 close by a microscope and a box of scientific instru- 
 ments are to be seen. 
 
 M. Berthelot, who in company with Dr. Roux 
 carefully inspected the statue, is said to have ex- 
 claimed, so struck was he with the likeness, " Je 
 revois Pasteur tel qu'il etait il y a vingt-cinq ans ! " 
 
 But if Pasteur had conquered his difficulties, he 
 had not vanquished all his opponents, and he 
 was continually harassed by attacks of sceptics, and 
 constantly occupied in exposing the imperfect 
 manipulations and false conclusions of his detractors. 
 During these years he was leading a life not only of 
 unremitting activity but of great mental tension. The 
 strain and anxiety told terribly upon him, and in the 
 autumn of the year 1868, at a critical moment, before 
 he had had time to convince his opponents of the truth 
 of his hypotheses and efficacy of his methods, he was 
 struck down by an attack of paralysis. The severity 
 of the attack was such that his recovery was at first 
 regarded as hopeless, and Pasteur himself was despon- 
 dent. " Je regrette de mourir," he said to a friend, 
 "j'aurais voulu rendre plus de services a mon pays." 
 His brain, however, was never affected, and his one 
 absorbing idea was the thought that he had not been 
 able to complete his researches on silkworm diseases. 
 One evening, Gernez tells us, how he was watching 
 beside Pasteur's bed all alone, and after in vain 
 endeavouring to distract his thoughts from his work, 
 allowed him to have his own way and unfold the 
 ideas of which his mind was full. To his great 
 
RESEARCHES ON SILKWORM DISEASES. 105 
 
 astonishment, Gernez found that they were all 
 definitely and clearly formulated, and he therefore 
 fetched pen and paper and wrote down, word for 
 w^ord, what Pasteur dictated to him, w^ithout altering 
 a single S3dlable. The next day he took the manu- 
 script to Dumas, w^ho could scarcely believe his eyes, 
 it havmg been produced exactly eight days after 
 Pasteur was seized wdth paralysis. This memoir of 
 Pasteur's is the note which appeared in the Compfes 
 rendus de VAcadeinie on October 26th, 1868, and 
 contains suggestions for an extremely ingenious 
 method of ascertaining in advance whether grame is 
 predisposed or not to the disease oi jiacherie. 
 
 Although Pasteur's physical condition became less 
 critical, he remained for two months completely 
 paralysed, and never in after-life recovered the full 
 qse of his limbs. 
 
 In the beginning of the year 1869, in January, 
 stung to the quick by the hostile criticism with which 
 his investio'ations and remedial measures were being" 
 received, he determined, although he could not yet 
 even move across his room, to go back to Alais and 
 superintend further experiments. " A scientific prin- 
 ciple was at stake, and an element of national wealth," 
 he urged upon those who endeavoured to dissuade 
 him from undertaking so risky an enterprise. 
 
 His son-in-law, M. Yallery-Radot, has vividly 
 described this painful expedition, so fraught with 
 anxiety to his family and those who accompanied him. 
 " II fallut ceder a son desir. Ah ! le terrible voyage 
 plein d'anxietes ! C'etait a quelques lieues d' Alais, a 
 Saint-Hippolyte-du-Fort, que se faisaient les essais 
 precoces. M. Pasteur s'arreta la. II s'installa, il campa 
 
106 PASTEUR. 
 
 pour mieux dire, avec sa famille et ses preparateurs 
 dans une maison plus que modeste, une de ces maisons 
 mesquines, froides et carrelees de province. Du fond 
 de son fauteuil, M. Pasteur dirigeait les experiences, 
 controlait I'exactitude des observations qu'il avait 
 faites Tannee precedente." 
 
 His indomitable courage and energy were rewarded, 
 and lie had the immense joy and satisfaction of con- 
 firming at every point and in every detail the truth of 
 his predictions and the efficacy of his preventive methods. 
 The noisy opposition of his adversaries, however, con- 
 tinued ; and the French Government hesitated, in the 
 face of such tenacious and clamorous contradictions, to 
 give official recognition to his method of grainage. 
 
 The Emperor Napoleon, however, came to Pasteur's 
 assistance, and proposed that he should visit a villa 
 near Trieste, belonging to the Prince Imperial, where 
 the cultivation of silkworms was carried on, which, 
 however, during the past ten years had failed utterly. 
 Pasteur accepted the offer with gratitude, and at once 
 started for Trieste, and so great was the success which 
 followed the application of his methods that the 
 sale of the cocoons realised a profit to the estate of 
 26,000 francs. 
 
 This signal success so impressed the Emperor that 
 he nominated Pasteur a Senator in July, 1870. There 
 was not time, however, for his promotion to be gazetted 
 before the Franco-German war was declared. Pasteur, 
 a patriot before all else, completely crushed by his 
 country's misfortunes, for the first time felt powerless 
 to do any work, and he retired to his old home at 
 Arbois. 
 
 The splendid vohunes containing the history of 
 
RESEARCHES ON SILKWORM DISEASES. 107 
 
 Pasteur's researches on silkworm diseases were pub- 
 lished in 1870, and in the preface Pasteur writes : — 
 
 "Altlioiigli I devoted nearly five consecutive years to the 
 laborious experimental researches which have affected my 
 health, I am glad that I undertook them, and that august 
 words* gave me the courage to persevere. The results which 
 I have obtained are perhaps less brilliant than those which I 
 might have anticipated from researches pursued in the field of 
 pure science, but I have the satisfaction of having served my 
 country in endeavouring to the best of my ability to discover a 
 remedy for great misery. It is to the honour of a scientific man 
 that he values discoveries which at their birth can only obtain 
 the esteem of his equals, far above those which at once conquer 
 the favour of the crowd by the immediate utility of their appli- 
 cation ; but in the presence of misfortune it is equally an 
 honour to sacrifice everything in the endeavour to relieve it. 
 Perhaps, also, T may have given young investigators the salutary 
 example of lengthy labours bestowed upon a difficult and un- 
 grateful subject." 
 
 * " Les maladies des versasoie" is dedicated to the Empress 
 (" Hommage de profonde reconnaissance et d'nne vive admiration 
 pour son esprit eleve et son grand Cffiur '') in recognition of the 
 gracious interest taken in his researches and the encouragement 
 o'iven to continue them. 
 
CHAPTER IX. 
 
 STUDIES OX BEER. 
 
 The condition of melancholy depression into which 
 the war of 1870 plunged Pasteur, and the intense 
 patriotism which his country's misfortunes roused in 
 him, may be gathered from the following letter which 
 he addressed from Arbois in January, 1871, to the 
 Dean of the Medical Faculty at the University of 
 Bonn : — 
 
 "111 1868 the Faculty of Medicine of the University of 
 Bonn did me the honour of bestowing up )n me the title of 
 Doctor of Medicine, in rec<ignition of my researches on fer- 
 mentation and on the part played by microscopic organisms. 
 
 "Of all the distinctions brought me by the discoveries 
 which I have l^een permitted to cany out since my entrance 
 upon a scientific career, now twenty-two years ago, there is not 
 one, I assure you, which gave me greater satisfaction It was, 
 in mj^ eyes, the public recognition of a secret thought, the trnth 
 of which I felt was asserting itself more and more, that my in- 
 vestigations had opened new horizons for medicine. Indeed, I 
 eagerly framed the diploma of honour conveying the resolution 
 of your Faculty, and ornamented my study with it. 
 
 " To-day the sight of this parchment is odious to me, and I 
 feel insulted to see my name, with the designation of Virwn 
 darrimiium with which you endowed it, placed under the 
 auspices of a name since devoted to the hatred of my country 
 — that of Ptex Guilelmus. 
 
 "Whilst expressing sincerely my deep respect towards you 
 and towards all the distinguished i)rofessors who appended their 
 signatures to the decision of the members of your Faculty, I obey 
 the cry of my conscience in begging you to erase my name from 
 the archives of your faculty and to take back this di[)loma, a 
 
STUDIES ON BEER. 109 
 
 marking a sense of the indignation inspired in a French savant 
 by the barbarism and hypocrisy of one, who to satisfy a 
 criminal ambition, persisted in the massacre of two great 
 peoples." 
 
 It will bo remembered by many that this feeHng 
 of antipathy and patriotic resentment never wore off ; 
 for, on the recent occasion of the festivities which 
 attended the opening of the Kiel canal, the Berlin 
 Academy of Sciences, at the instigation of the 
 Emperor, offered Pasteur, in the most flattering 
 terms, a Prussian distinction, but only to find 
 that the deep wound received more than twenty years 
 before was still unhealed. Pasteur replied that, whilst 
 appreciating the honour as a savant, he could not as a 
 Frenchman forget the war of 1870, and that he would 
 never be able to accept a German decoration. 
 
 That Pasteur's old energy was returning, and that 
 he was growing restless and anxious to be once more 
 up and doing, assisting by some means or other to re- 
 trieve the misfortunes which had fallen on his country, 
 we learn from a letter addressed about a couple of 
 months later to his old assistant and friend, Duclaux : — 
 
 "My head is full of the most beautiful plans for work. The 
 war ]jas let my brain lie fallow. I am ready for fresh under- 
 takings. Alas ! XJerhaps I am deceiving myself. Come what 
 may, I shall try. Ah ! if I only were rich— a millionaire ! I 
 would say to you, to Ptaulin, to Gernez, to Van Tieghem, etc., 
 ' Come, we will transform the world by our discoveries ! ' How 
 happy you are to be young and strong ! Oh, if I only were so, 
 to start afresh a new life of study and work. Poor France, 
 dear country, could I but help to raise you from your 
 disasters !" 
 
 Just as Pasteur was starting for Paris, full of 
 energy, and impatient to carry out the investigations 
 
110 PASTEUR. 
 
 which he had been planning with so much enthusiasm 
 in his retirement,, the Commune was declared, and he 
 accepted instead Duclaux's invitation to come and 
 work in his laboratory at Clermont-Ferrand, where he 
 was at this time professor in the Faculty of Sciences. 
 
 It was natural that Pasteur should once more turn to 
 those studies on fermentation to which he had devoted 
 so many years of labour, and which he had so re- 
 luctantly abandoned when he consented to undertake 
 the investigation of the silkworm disease. Even 
 during his researches on pebrine and flacherie, which 
 we have seen he pursued with so much enthusiasm 
 and energy, he had room for a regret that he had been 
 obliged to sever himself from his former investigations. 
 In his preface to the splendid volumes in which he 
 has brought together his studies on the diseases of 
 silkworms, he writes : — 
 
 " One day — it was, I think, at the beginning of the month 
 of October, 1868— encountering Dumas as I was coming out 
 from one of the meetings of the Academy of Sciences, I said to 
 him, ' Ah, I made a very great sacrifice for you in 1865.' A 
 discussion had just taken place at this meeting on various 
 questions relative to fermentations and contagion, and it had 
 roused up afresh all my regrets." 
 
 But another and ver}^ different consideration also 
 led Pasteur to return to his old subject, and this was 
 the hope that, by investigating the fermentations 
 incidental to the brewing of beer, he might be able to 
 succeed in so improving the manufacture of French 
 beers that they should be in a position to compete 
 with those so successfully produced in Germany, and 
 that he might thus secure some commercial advantage 
 for his now over-burdened country. 
 
STUDIES ON BEER. Ill 
 
 " L'idee de ces recherches m'a ete inspiree par nos 
 malheurs. Je les ai entreprises aussitot apres la 
 guerre de 1870 et poursuivies sans relPiche depiiis 
 cette epoque, avec la resolution de les mener assez 
 loin pour marquer d'un progres durable une industrie 
 dans laquelle 1' Aliemagne nous estsuperieure." These 
 words figure on the first page of that monumental 
 work " Etudes sur la biere," in which he has collected 
 the numerous researches with which he was occupied 
 between the years 1871 and 1876. 
 
 It must not, however, be supposed that this 
 volume constitutes in any sense a handbook to the 
 practice of brcAving ; of breweries there is hardly 
 any mention, and but little space — a single chapter 
 only — is devoted to the description of the methods 
 recommended by Pasteur for the improvement in the 
 manufacture of beers. 
 
 The following terse summary of the practical 
 results of his investigations, given by Pasteur himself, 
 will afford the reader an idea of the general direction 
 which his researches took in endeavouring to sub- 
 stitute a scientific basis for the empirical methods 
 which, previously employed, dominated the production 
 of beer. 
 
 "We have shown, firstly, how the changes which 
 are produced in the beer-yeast, in the wort, and in 
 the beer itself are due to the presence of microscopic 
 organisms of a totally different nature from those 
 belonging to the so-called yeast proper. These 
 organisms, by the correlative products resulting from 
 their multiplication in the wort, in the beer -yeast, and 
 in the beer, denaturalise the properties of the latter 
 and militate in consequence against its preservation. 
 
112 PASTEUR. 
 
 " We have further demonstrated that these organ- 
 isms responsible for such alterations, these disease- 
 ferments, do not appear spontaneously, but that on 
 every occasion when they exhibit themselves in the 
 wort or in the beer it is because they have been 
 brought thither from without, either by dust in the 
 air, or by the vessels, or by the raw materials which 
 the brewer's art employs. 
 
 " We also know that these disease-ferments or their 
 germs perish in malt-wort when the latter is raised to 
 the temperature of boiling, and, as a necessary con- 
 sequence of this fact, we have seen that malt-wort 
 exposed to pure (sterile) air undergoes no sort of 
 fermentation after having been boiled. 
 
 " Since all the disease-germs of wort and beer are 
 destroyed in the copper in which the wort is heated, 
 and that the introduction of yeast from a pure beer 
 cannot import into the latter any foreign ferment of 
 a detrimental nature, it follows that it ought to 
 be possible to prepare beers incapable of develop- 
 ing any mischievious foreign ferments whatever, 
 provided that the wort coming from the copper 
 is protected from ordinary air, or only brought in 
 contact with pure air during the cooling and further 
 manipulations, and that it is then fermented with 
 pure yeast, and that the beer, after the completion of 
 the fermentation, is placed in vessels carefully freed 
 from disease ferments." 
 
 That Pasteur's patriotic ambition to serve his 
 country by his researches was fulfilled, we know from 
 the graceful tribute which was accorded to his "Etudes" 
 by French brewers at a congress held in the year 
 1889, whilst the power they have wielded in stimu- 
 
STUDIES OX BEER. 113 
 
 lating and suggesting scientific researches in the 
 domain ot brewing is recognised all over the world. 
 The important work on the study of jDure yeast 
 so splendidly inaugurated by Pasteur has been no- 
 where more fully appreciated than in Copenhagen, 
 where Jacobsen erected and endowed the now Avorld- 
 famed Carlsberg experimental laboratory for the 
 study of fermentation problems, and which, under 
 the able direction and guidance of Hansen, has 
 produced such valuable scientific and practical results. 
 In the hall of this Carlsberg Institution Jacobsen has 
 placed a bust of Pasteur, as a tribute to the genius of 
 the man whose labours threw such important light 
 on the difficult and so long concealed problems of 
 fermentation. 
 
 We have already pointed out that the portion of 
 this famous volume devoted to the consideration of 
 the practice of brewing is comparatively small, only a 
 few out of the 383 octavo pages of which it is 
 composed being directly occupied with the manu- 
 facture of beer. A closer inspection of its contents 
 shows us that it contains an account of the numerous 
 and varied subjects attacked by Pasteur, and a record 
 of the original and laborious experiments which he 
 made in elucidating them during these years. ^Ye 
 find him carrj-ing out experiments to prove the 
 freedom from micro-organisms of urine and blood in 
 their normal condition and collected with proper 
 precautions. He is embroiled in a discussion with 
 Fremy on spontaneous generation. He carries out 
 a number of coinparative examinations of ah in dif- 
 ferent localities, and maps out their distribution in 
 greater detail than he attempted in the original 
 
 H 
 
114 PASTEUR. 
 
 experiments on the presence of germs in air already 
 referred to {see p. 59). He takes for example a 
 series of thirty flasks containing sterile grape-must. 
 Ten he opens in the garden of the Ecole Normale, 
 ten on a landing of the second floor within the 
 building, ten in the principal room of his laboratory, 
 where a short time previously the dust had been 
 purposely disturbed. Of the first series opened in 
 the garden only one flask underwent alteration, of 
 the second series four broke down, whilst of those 
 flasks opened in the dust-laden air of the laboratory 
 not a single one escaped infection. 
 
 The centre of gravity of this volume is, however, 
 undoubtedly the new theory of fermentation which 
 it contains, and which may be summarised in the 
 words, " Fermentation is life without oxygen." 
 
 To the enunciation of this theory Pasteur was 
 led by a careful study of the phenomena exhibited 
 on the one hand by the life of aerobic organisms 
 in the absence of air, and, on the other hand, of 
 anaiirobic organisms in the presence of air. 
 
 It had been asserted since 1857 by Bail that 
 the mould Mucor onucedo, which is so common on 
 horse manure, becomes transformed into brewer's 
 yeast if grown out of contact with air by immersion 
 in a saccharine liquid, and that the latter under these 
 conditions sutfers the ordinary alcoholic fermentation. 
 Pasteur repeated this experiment, using special 
 precautions, and was able to confirm the apparent 
 transformation and the alcoholic fermentation con- 
 sequent thereon. He, however, showed that the 
 round or oval cells obtained were not veritable yeast, 
 but that they only simulated the latter, and that 
 
STUDIES OX BEER. 115 
 
 the change in form was only a concomitant of 
 the change in function under the altered conditions 
 of life, for on bringing these yeasthke cells to the 
 surface they again gave rise to an ordinary mould 
 mycehum which destroyed the sugar by oxidation. 
 The power of decomposing the sugar into alcohol 
 and carbonic anhydride is thus only possessed by 
 the inucor mucedo so lono- as it is o-rowino' in the 
 absence of air, or, in other Avords, the onucor onucedo 
 becomes a ferment when deprived of oxygen. 
 
 Pasteur endeavoured to trace the counterpart of 
 these phenomena in the behaviour of ordinary 
 yeast when grown in the presence and absence of 
 air respectively. 
 
 Thus he found that yeast could grow in the 
 absence of air, and although the growth was a very 
 feeble one and the absolute amount of sugar trans- 
 formed into alcohol and carbonic acid very small, 
 yet the w^eight of sugar so • transformed per unit 
 weight of yeast present was very large indeed (150 to 
 200 of sugar : 1 of yeast). 
 
 On the other hand, by admitting a small quantity 
 of oxygen, the growth of yeast is more abundant and 
 the fermentation accelerated, but the transformation 
 of sugar for unit weight of yeast present is less 
 than in the entire absence of oxygen (67 of 
 sugar : 1 of yeast). By further increasing the 
 quantity of oxygen, the disappearance of the 
 sugar is still more rapid and the grow^th of 
 yeast still more abundant, but there is hardly any 
 alcohol formed, the sugar having principally suffered 
 oxidation instead of decomposition ; moreover, the 
 amount of sugar which has disappeared per unit 
 H 2 
 
116 PASTEUR. 
 
 weight of yeast present is still lower than in the 
 previous case (4 to 5 of sugar : 1 of yeast). 
 
 It would be out of place here to discuss the 
 criticisms to which this theory of fermentation has 
 given rise — criticisms which at the present day are 
 being actively carried on ; one of the principal objec- 
 tions to the acceptance of Pasteur's views being the 
 omission of all consideration of the element of time 
 in estimating the fermentative power of yeast. 
 
 Before, however, leaving this fermentation theory 
 of Pasteur's, which it is to be hoped will still continue 
 to stimulate research in the future, as it has done in 
 the past, we would point out two very remarkable 
 confirmations which this theory receives : first, in 
 connection with industrial practice, where the produc- 
 tion of yeast is the object of the manufacturer, the 
 liquids in which the yeast is grown are kept as fuUy 
 aerated as possible, experience showing that thus the 
 maximum transformation of sugar into yeast cells is 
 secured. On the other hand, the discovery in 1869 
 by Lechartier and Bellamy that the vegetable cells 
 present in ripe fruits transform a part of the sugar 
 which they contain into alcohol if the fruits in ques- 
 tion are preserved in an atmosphere of carbonic 
 anhydride, would tend to show that the production 
 of alcohol from sugar is a more or less general j^roperty 
 of vegetable protoplasm when deprived of free oxygen, 
 irrespectively of the nature of the cells in which this 
 protoplasm is contained. 
 
 Within the present year the discovery has been 
 made by E. Buchner that a soluble principle giving 
 rise to the alcoholic fermentation of sugar may be 
 extracted from yeast cells, and for which the name 
 
STUDIES ON BEER. 117 
 
 zymase is proposed. This important discovery should 
 throw a new hght on the theory of fermentation, as 
 it will now be possible to attack the problem in a 
 new and much more decisive manner. Thus it is 
 presumably very improbable that the action of 
 this soluble zymase is influenced by the presence or 
 absence of air, but it is very possible, on the other 
 hand, that the amount of zymase produced in a given 
 yeast cell may depend largely on whether the latter is 
 supplied with, or deprived of, free oxygen. 
 
 Of great interest is Pasteur's excursion, arising out 
 of his studies of aerobic and anaerobic oro-anisms re- 
 spectively, into the question of the transformation of 
 one species of micro-organism into another. The idea 
 had become current amongst certain German and 
 French biologists that moulds could give rise to 
 alcoholic fermentation, that the spores of these little 
 vegetable growths could produce real beer yeast ; an 
 opinion already expressed, as we have seen, by Bail in 
 1857 with respect to the mould niucor onucedo. Now, 
 however, we find a certain M. Trecul affirming posi- 
 tively in 1872 that "all varieties of penicilliuvi 
 moulds, especially when young and vigorous, will 
 exhibit this transformation into yeast." 
 
 Pasteur, although he pubhcly controverted the 
 assertion that yeast could change into penicillium 
 glaucum — such a statement being entirely at variance 
 with his own experience — was not really in a position 
 absolutely to repudiate the doctrine of the transmut- 
 ability of species, for at this time he was under the 
 firm conviction that the onycoderina vini could 
 change under suitable conditions into an alcoholic 
 yeast. 
 
118 PASTEUR. 
 
 More extensive investigations, however, convinced 
 him that the yeast cells which he discovered in his 
 solutions soAvn with mycoderma vini did not OAve 
 their source to the latter, but to the outside air, and 
 by elaborate precautions to exclude this chance of 
 error Pasteur tells us that, " Never again did I see 
 3^east or an active alcoholic fermentation follow the 
 submersion of the flowers {mycoderma vini) either in 
 the flasks themselves or in the experimental flasks 
 connected with the former. ... At a time when the 
 notion of the transformation of species was so easily 
 adopted, perhaps because it dispensed with rigorous 
 accuracy in experimenting, it is not without interest 
 to note that in the course of my researches on the 
 culture of microscopic plants in a state of purity, I 
 had once reason to believe in the transformation of 
 one organism into another, in the transformation 
 of inycoderma vini or cerevisia^ into j^east, and that 
 at this time I was in error : 1 did not know hoAv to 
 avoid the very cause of illusion in my own case which 
 the confidence in my theory of germs had so often 
 enabled me to discover in the observations of others." 
 Still occupied with this subject of the supposed 
 transmutability of moulds into yeast, we find him ask- 
 ing himself, Where do these ferments themselves come 
 from? what is the origin of the grape yeast, for ex- 
 ample ? To answer this question he visits vineyards 
 and makes careful microscopic examinations of the 
 dust obtained from the surface of grapes; he inoculates 
 some of this dust into sterilised grape-must and ob- 
 serves the growths which ensue, and describes the 
 appearance of the yeast cells which make their 
 appearance. By making examinations of grape-dust 
 
STUDIES ON BEER. 119 
 
 collected during different stages in the development 
 of the fruit, he ascertains that whilst the latter is 
 green, between the end of July and middle of August, 
 no yeast cells are present on their surface, that later 
 and during September the number continually in- 
 creases, whilst in the subsequent months of the year 
 they are only discoverable with difficulty. 
 
 - He, however, still leans towards the idea that 
 these yeasts may have their origin in a mould called 
 der)iatiuvi, abundantly present on the surface of 
 leaves and especially prevalent on the wood of the 
 vine at the time of the vintage, for he distinctly says, 
 p. 177 : " All conduces to the belief that at this period 
 of the year (autumn) one or more of these dematiums 
 furnish yeast cells." 
 
 In 1879 Pasteur carries out further experiments, 
 the results of which led him to abandon this view of 
 the origin of yeast cells, whilst he makes it an oppor- 
 tunity of exhibiting once more the truth of his 
 vitalistic principle of fermentation phenomena. 
 
 A posthumous essay by CI. Bernard raised once 
 more objections to the acceptance of Pasteur's dictum 
 that " A ferment is a living form which originates 
 from a germ " ; and the day after the appearance of 
 this essay of Bernard's, P.isteur, bethinking himself of 
 his investigations on the presence of yeasts on grapes 
 at different periods of their development, plans a new 
 experimental campaign, and, armed with a supply of 
 small greenhouses, which he had had constructed, he 
 remarks " sans trop de souci de la depense," he starts 
 at the beginning of August for the Jura, where he 
 possessed a small vineyard of his own. 
 
 Here he erects his greenhouses, covering up 
 portions of the vines, whilst at the same time, fearing 
 
120 PASTEUR. 
 
 lest any defect in the fitting up of his glass houses 
 should permit the access of air from without, he also 
 takes the precaution of wrapping up some specimens 
 of grapes in sterilised cotton-wool. Meanwhile he had 
 satisfied himself that at the time when he, as it were, 
 imprisoned the fruit there were no yeasts present on 
 their surface. Towards the commencement of October 
 the greenhouse grapes were ripe, and on the tenth of 
 the month he made his first comparative examination 
 of the condition, as regards yeast cells, of the covered 
 and uncovered grapes respectively. He found that in 
 no single instance could he obtain alcoholic ferment- 
 ation by means of the grapes protected from the 
 access of air ; on the other hand, when he uncovered 
 the fruit and allowed it to remain unprotected in the 
 open air, so that the yeast cells could settle upon its 
 surface, he was subsequently easily able to induce 
 fermentation by means of the grapes. In the case of 
 the protected or non-fermenting grapes no yeasts 
 were present : in the case of the unprotected or fer- 
 menting fruit, yeast abounded. Thus by a most 
 original experiment did Pasteur once more illustrate 
 the truth of his views on the dependence of fermenta- 
 tion phenomena upon life. 
 
 We remarked above that in these experiments 
 Pasteur had effectually disposed of his original idea 
 as to the supposed connection existing between the 
 common mould dematium and the origin of yeast 
 cells, and it was the repetition of his experiments 
 which demolished this theory completely Avhen re- 
 cently resuscitated. 
 
 During the last two years the question of the 
 derivation of yeasts from moulds has been energetically 
 revived by more than one accomplished investigator 
 
STUDIES ON BEER. 121 
 
 and well-known authority on fermentation pheno- 
 mena. ])r. Jorgensen, of Copenhagen, has been 
 especially associated with this revival of ideas so 
 prevalent at the time when Pasteur was carrying out 
 the above investigations. The relationship, however, 
 which Jorgensen, J uhlcr and others have endeavoured 
 to establish between dematiuon and yeast cells has 
 not borne the test of the rigorous and critical examina- 
 tion to which it has been submitted by several other 
 investigators, and at present we have no experimental 
 justification for refusing to yeasts the position of an 
 independent group of organisms. 
 
 As regards the dissemination of yeasts, we may 
 refer the reader to some very interesting investiga- 
 tions just published by Dr. Berlesc in an Italian 
 scientific journal, on the part played by insects in the 
 distribution of alcoholic ferments. From these re- 
 searches it appears that ants, in the course of their 
 journeyings over grapes in search of food, deposit 
 large quantities of yeast cells, the number and variety 
 of the latter depending, seemingly, upon the source 
 from which the ants were originally obtained. Thus 
 when these insects were derived from vineyards, and 
 made to crawl over sterilised grapes, the germs they 
 conveyed were found to be chiefly moulds, together 
 with some varieties of yeast known as Saccharoniyces 
 apiculatus and elli'psoideus. When the ants were 
 collected from the trunks of oak-trees, they brought 
 an abundance of 8. cqnculatus, with some aS\ ellijJ- 
 soideuH and 8. pastor ianus. If these insects, however, 
 were transferred from olive-trees to grapes, no yeasts 
 whatever were subsequently foimd on the latter. 
 Berlcse lias also shown that flies materially assist in 
 the process of infecting grapes with yeast cells, as 
 
122 PASTEUR. 
 
 well as with dematium and other moulds. This is 
 effected by means of the excreta of flies, the yeast 
 cells being able to pass uninjured through the 
 digestive tract of these insects. Not only, however, 
 are yeasts able to live within the bodies of flies, but it 
 has been shown that they can also multiply in a very 
 remarkable manner under these circumstances. Thus 
 a fly originally fed with a small drop of must contain- 
 ing about 500,000 yeast cells {S. apiculatus), and 
 subsequently only fed with sterilised must, emitted 
 in the course of the eight days during which it 
 received no further supply of yeast about 35,000,000 
 of such cells. It would appear, therefore, that not 
 only may ants and flies distribute alcoholic ferments, 
 but that these insects may actually furnish such 
 micro-organisms with a nursery in which their 
 vitality is so promoted - that they are able to thrive 
 and multiply abundantly. 
 
 ^ ^ ^ ^- ^ 
 
 Throughout this volume of Etudes, Pasteur shows 
 unmistakable signs that his thoughts and ideas were 
 leaning in the direction of the applications which his 
 methods and discoveries might have in the inter- 
 pretation and treatment of the phenomena of disease. 
 
 For five years he was, we have seen, investigating 
 the diseases of silkworms, and although to all appear- 
 ances he abandoned this direction of research, Avhen 
 he again took up the more prosaic study of yeasts, 
 yet in reality he was becoming more and more deeply 
 engrossed with the prospects which were gradually 
 unfolding themselves before him of the far-reaching 
 and beneficent results which might follow from a 
 more intimate and extended knowledge of the nature 
 and character of these microscopic forms of life. 
 
CHAPTER X. 
 
 INTRODUCTION TO THE STUDY OF INFECTIOUS DISEASES. 
 
 Already in his studies on silkworms, Pasteur's first 
 experience in the domain of disease, the dawn of a 
 new era in the contest of man with contagion, opens 
 up before him. " II est au pouvoir de Thomme," he 
 writes, " de faire disparaitre de la surface du globe les 
 maladies parasitaires, si, comme c'est ma conviction, 
 la doctrine de la generation spontanee est une 
 chimere." 
 
 Again, in his " Etudes sur la biere," he makes the 
 signiticant suggestion that " L'etiologie des maladies 
 contagieuses est pent etre a la veille d'en recevoir une 
 lumiere inattendue." 
 
 Indeed, his researches had already borne fruit in 
 many of the directions indicated by the above words, 
 for Payer and Davaine were encouraged to once 
 more approach the investigation of anthrax ; " les 
 petits corps filiformes," which they had observed in 
 the blood of animals infected with this disease as far 
 back as the year 1850, becoming endowed, as they 
 acknowledge, with an entirely new significance and 
 importance since the publication of Pasteur's researches 
 on the butyric ferment in 1861. 
 
 But amongst a number of achievements in medi- 
 cine and surgery, which their authors gratefully 
 ascribe to the inspiration and suggestion which they 
 
124 PASTEUR. 
 
 had received from a study of Pasteur's brilliant 
 researches of this period, by far the greatest and most 
 important development is that which is universally 
 associated with the name of Lister, and which has 
 revolutionised the practice of surgery by introducing 
 the antiseptic and aseptic treatment of wounds. 
 
 That this outcome of his researches was viewed 
 with special satisfaction and pride by Pasteur we may 
 gather from the fact that he reproduces in full in the 
 pages of his " Etudes sur la biere," the letter addressed 
 to him in 1874, " par le celebre chirurgien d'Edim- 
 bourg, le Dr. Lister," who in forwarding Pasteur a 
 memoir on the lactic ferment, takes the opportunity 
 of sending him his most warm thanks " for having, by 
 your brilliant researches, demonstrated the truth of 
 the theory of putrefactive germs, and having thus 
 given me the only principle which could lead to 
 the success of the system of antiseptics." 
 
 Many years later, on the occasion of Pasteur's 
 jubilee celebration. Lister, who was present as repre- 
 sentative of the Royal Society, embraced the oppor- 
 tunity of again pubKcly referring to the debt of 
 gratitude which the art of surgery owed to Pasteur's 
 researches, and, rising and addressing M. Pasteur, 
 pronounced the following words — as remarkable 
 for their impressive truth as for their beautiful 
 modesty : — 
 
 " Truly, there does not exist in the entire world 
 any individual to whom the medical sciences owe 
 more than they do to you. 
 
 " Your researches on fermentation have thrown a 
 powerful beam, which has lightened the baleful dark- 
 ness of surgery, and has transformed the treatment of 
 
THE STUDY OF INFECTIOUS DISEASES. 125 
 
 wounds from a matter of uncertain and too often 
 disastrous empiricism into a scientific art of sure 
 beneficence. Thanks to you, surgery has undergone 
 a complete revokition, which has deprived it of its 
 terrors and has extended almost without limit its 
 efficacious power." 
 
 Indeed, as Dr. Roux has recently so aptly stated : 
 " C'est grace k une experience bien faite sur la fer- 
 mentation que Pasteur, qui de sa vie n'a tenu un 
 bistouri [dissecting knife], ni fait un pansement 
 [bandage], a sauve plus de blesses que tous les 
 maitres de la chirurgie." 
 
 Later on, in the year 1876, Pasteur received a letter 
 from Professor Tyndall, in which the latter refers to 
 the revival of the idea of spontaneous generation by 
 Dr. Bastian in this country, which had induced him 
 (Professor Tyndall) to take up the defence of Pasteur's 
 position, to repeat his experiments, and to vindicate 
 afresh the " inattackable exactitude of your conclusions." 
 " For the first time," continues Professor Tyndall, " in 
 the history of science we have the right to indulge 
 the hope sure and certain, with regard to epidemic 
 disease, that medicine will soon be delivered from 
 empiricism and placed upon a sound scientific basis. 
 When this great day shall come, humanity, in my 
 opinion, will know how to recognise that to you is 
 owing the greater portion of its gratitude." 
 
 Pasteur has himself described the "vive satisfac- 
 tion " which this letter gave him, on learning that his 
 researches had received the support of investigations 
 made by a " savant, renomme par sa rigueur experi- 
 mentale autant que par la brillante et pittoresque 
 clarte de tous ses ecrits. La recompense comme 
 
126 PASTEUR. 
 
 rambition du savant est cle conquerir I'approbation 
 de ses pairs on celle des maitres qii'il venere." 
 
 The excursion thus made by Tyndall into the 
 study of microbial hfe, it may be incidentally re- 
 marked, has another special interest for us, as it was 
 undoubtedly through this master of attractive ex- 
 position that many of our countrymen received their 
 baptism in bacteriology. Not a few workers in this 
 field at the present day had their enthusiasm for its 
 study aroused by his magnetic influence. 
 
 Whilst, however, following with the closest atten- 
 tion and deepest interest the developments of his 
 ideas in the hands of the medical world, whilst re- 
 joicing in the partial realisation of his dream "that 
 his researches might prepare the way for a deeper 
 investigation of the origin of disease," Pasteur was 
 not altoofether satisfied with the manner in which the 
 further extension and application of his methods was 
 being carried on. 
 
 Dr. Roux describes how at this time " the experi- 
 ments published by the members of the medical 
 profession frequently appeared to him incomplete, 
 the methods adopted defective, and the conclusions 
 arrived at unjustifiable, and more Hkely to compromise 
 the good cause than to promote it." 
 
 Pasteur himself sounds a strong note of warning 
 in the following interesting extract, taken from the 
 " Etudes sur la biere " : 
 
 " I am the first, however, to regret that inferences are drawn 
 beyond the scope of the facts acquired. The exaggeration of 
 new ideas infallibly leads to a reaction, which again over- shoot- 
 ing the mark, casts disfavour upon what is correct and fertile 
 in these ideas. Already in divers ways, and as a rebound from 
 
THE STUDY OF INFECTIOUS DISEASES. 127 
 
 the exaggerations to which I have referred, one can perceive a 
 
 thoughtless tendency to deny that certain diseases can be due 
 to specific ferments of the same nature as those which have 
 been discovered during the past twenty years, ferments both 
 organised and living. All through one ought to keep to facts, 
 control those which are announced if one is led to doubt them, 
 study them afresh, and only deduce from them those ideas 
 which, so to speak, can be regarded as justified, for the explora- 
 tion of the subject has as yet hardly begun. 
 
 " Unfortunately, doctors delight in premature generalisations. 
 Many amongst them are men of rare distinction either natural 
 or acquired, endowed with lively intelligence, with a ready flow 
 of elegant phrases, but the more distinguished they are the 
 more they are absorbed by their craft, and the less leisure have 
 they for the labour of research. Urged on, nevertheless, by 
 that passion for knowledge belonging to men of distinction and 
 which is fostered by the increasing scientific interest manifested 
 by the upper classes, they eagerly get hold of easy, specious 
 theories, the more general and appropriate to vague explanations 
 as they are more weakly founded on facts. 
 
 " When we see beer and wine undergoing profound 
 changes l)ecause these liquids have furnished a refuge for 
 microscopic organisms which have there established themselves 
 by some sort of mysterious chance, and have subsequently 
 multiplied, how can we avoid being possessed by the thought 
 that phenomena of the same order can and must of necessity 
 be found sometimes in the case of men and animals 1 
 
 " But if we are inclined to believe that this is so, because we 
 consider it likely and possible, let us before asserting the same, 
 recall the motto on this book* : ' The greatest distortion of the 
 intelltct is to believe things because one wishes them to exist.' " 
 
 Yet Pasteur still hesitated himself to undertake the 
 responsibility of pursuing these investigations. " I am 
 neither a doctor nor veterinary surgeon " he declared 
 with modest diffidence. The world knows, however, 
 now how the prophetic words written by Boyle two 
 
 * " Etudes sur la biere." 
 
128 PASTEUR. 
 
 centuries before — "The man who shall probe to the 
 bottom the nature of ferments and of fermentations' 
 will, doubtless, be much more capable than any other 
 of giving a true explanation of the divers morbid 
 phenomena, both of fevers as well as of other affec- 
 tions " — have been fulfilled in the person of Pasteur. 
 
 The long apprenticeship which he had served in 
 the elucidation of abstruse chemical problems, and in 
 the revelation of the functions of micro-organisms in 
 the economy of nature, had e( quipped Pasteur, as no 
 man before him had ever been, not only with the 
 power of comprehending the complex problems of 
 disease, but also with the means for their successful 
 solution. 
 
 Durinof his laborious researches on the maladies of 
 beer, Pasteur had not only accumulated an immense 
 amount of experience, but he had introduced extremely 
 important improvements in his methods of investiga- 
 tion. Thus he had succeeded in obtaining for the 
 first time cultivations of micro-organisms in a state 
 of purity or freed from all foreign germs, by con- 
 ductino- a series of successive inoculations from one 
 
 o 
 
 liquid medium to another, or by what is now known 
 as " selective cultivation." By this method he isolated 
 a number of different varieties of yeasts and bacteria, 
 and submitted them to minute and careful observa- 
 tions. He had abandoned the exclusive use of mineral 
 solutions for the cultivation of germs, and had intro- 
 duced the important step of ascertaining the medium 
 most suitable to the vitality and growth of each variety 
 of micro-organism, and of then adopting the same as 
 its food-material. Not only was his knowledge of the 
 physiology and morphology of micro-organisms more 
 
THE STUDY OF INFECTIOUS DISEASES. 129 
 
 profound than that of any of his contemporaries, but 
 the refined technique of his methods, in the develop- 
 ment of which he had been so ably assisted by his 
 faithful assistants Joubert, Chamberland, and Roux, 
 placed Pasteur in an unrivalled position to commence 
 his attack upon the etiology of infectious diseases. 
 
 Thus Pasteur, almost in spite of himself, was 
 hurried on from being a simple spectator of the 
 labours of others, prompted by his researches, into 
 becoming the inspired leader in whose footsteps a 
 generation of ardent disciples have since trodden ; 
 and from this time onward down to the day of his 
 death Pasteur never swerved from the pursuit of 
 those researches by the light of which the principles 
 of contagion were first revealed, and from which the 
 revolution now slowly gaining ground in the treat- 
 ment and prevention of disease has directly arisen. 
 
 Indeed, the hope is justified, in the words of a 
 modern French writer, that " When man learnt how 
 to protect himself from the wild beasts he made the 
 first step in civilisation. To-day man is learning how 
 to defend himself from the microbes — it is a step of 
 equal importance. A day will come when in Berhn, 
 in London, in Paris, man will not die of diphtheria, of 
 typhoid, of scarlet fever, of cholera, or of tuberculosis, 
 any more than he dies in these cities to-day from the 
 venom of snakes or from the tooth of wolves." 
 
CHAPTER XL 
 
 RESEARCHES ON ANTHRAX. 
 
 At the already ripe age of fifty-five, then, we find 
 Pasteur devoting himself with all the energy and 
 enthusiasm of youth to the study of pathological 
 phenomena, and perhaps in the whole career of this 
 remarkable man there is no spectacle which is more 
 striking" or instructive. 
 
 The best years of his life had, we have seen, been 
 spent in studying the crystalline forms of obscure 
 chemical compounds, in unravelling the chemical 
 changes taking place in the brewer's vat, in the wine 
 cask, in the vinegar factory ; he had devoted years 
 to discredit and overthrow the doctrine of the spon- 
 taneous generation of life — all of them subjects 
 entirely outside the perspective of the medical 
 practitioner or of afflicted humanity in general; and 
 yet at a period of life when too many scientific men 
 are contemplating repose and escape from their 
 laboratories, Pasteur plunged into an entirely new 
 sphere of research, in which he was not only to win 
 his most glorious laurels but to hght his fiercest 
 battles. 
 
 The malady which first attracted the attention 
 of Pasteur was the infectious cattle disease called 
 anthrax, a disease known and dreaded all over the 
 world, and which in France alone in some years had 
 
RESEARCHES ON ANTHRAX. 131 
 
 meant a loss to the country of from fifteen to twenty 
 millions of francs. 
 
 For centuries this scourge had been wrapped in 
 mystery, and assuming as it did different guises 
 according to the class of victims it attacked, the 
 discovery of its essential character had been rendered 
 yet more difficult and perplexing. It was only in the 
 year 1850 that any real light had been thrown upon 
 its nature by the discovery that it was communicable 
 from one animal to another, and that although ex- 
 hibiting different symptoms in different animals as 
 well as in man, it was in each case one and the same 
 agent which was responsible for the various morbid 
 phenomena. At the time when the commission of 
 inquiry appointed by the medical association of Eure 
 and Loir was carrying on the investigations which 
 had resulted in the above important conclusions, 
 Rayer and Davaine published the now classical 
 memoir on the etiology of anthrax, in which they call 
 attention to the " small, thread-like bodies about 
 twice as long as a blood corpuscle " found in the 
 blood of anthrax infected bodies. This observation, 
 the importance of which impresses us so forcibly 
 at the present day, recognising in it as we do 
 the original centre from which all the subsequent 
 researches on the etiology of infectious diseases have 
 sprung, received, however, but little attention at the 
 time of its publication. 
 
 In fact, the discovery by Rayer and Davaine of 
 these filiform bodies in anthrax blood, like the 
 previous revelations of Latour and Schwann con- 
 cerning the yeast cells in fermenting liquids, fell 
 upon irresponsive soil. Both were opposed to the 
 I 2 
 
132 PASTEUR. 
 
 scientific Zeitgeist prevailing when they were pub- 
 Hshed, and both announcements were stifled and 
 prevented from bearing fruit for many years, through 
 the opposition which they encountered from the 
 leaders of science of the time. 
 
 This indift'erence is perhaps not so astonishing if 
 we remember, that at this period leading scientific 
 men, like Helmholtz, Ludwig, Brticke, Dubois 
 Reymond, and their numerous followers, regarded 
 the complete explanation of the phenomena of life 
 on a physico-chemical basis as assured, and merely 
 a question of time. Observations, therefore, which 
 tended to shift the weighty responsibility of such 
 complex phenomena as infection and disease upon 
 minute parasitic organisms in the blood and tissues, 
 appeared not only inadequate but almost ridiculous. 
 
 It was the particular mission of Pasteur, with his 
 well directed and irresistible energy, to remodel this 
 Zeitgeist, to overthrow the oligarchical sway of these 
 captains of science, and so clear the way for a new 
 order of things. 
 
 Notwithstanding the unsympathetic attitude of 
 the leaders of science, this new line of research was 
 silently proceeding. These filiform bodies, discovered 
 by Rayer and Davaine, Avere again seen and emphasised 
 in 1855 by Pollender, but immediately afterwards 
 brought into discredit by Brauell, only to be again 
 rehabilitated in 18G0 by Delafond, who first suc- 
 ceeded in cultivating them in blood outside the body. 
 
 We have seen (see p. 128) how Rayer and Davaine 
 were themselves unconscious of the epoch-making 
 nature of their original discovery of the " petits corps 
 filiformes" in cases of anthrax, until their interest 
 
RESEARCHES ON ANTHRAX. 133 
 
 and attention was again aroused in the matter by 
 the researches of Pasteur on fermentation. Davaine 
 returned with renewed energy to the re-investigation 
 of anthrax, and in 1863 he was able to cite hundreds 
 of experiments in which he had discovered these 
 particular parasites in the blood of animals infected 
 with anthrax, whilst he also demonstrated beyond 
 question the contagious character of the disease by 
 taking a small drop of blood from one infected animal 
 and inoculating it into another healthy animal, and 
 producing thereby the saixie disease in the latter, and 
 so on through a series of eleven animals, with in- 
 variably the same result, that the blood became 
 invaded with myriads of these same small rod-like 
 bodies. In the course of his researches Davaine dis- 
 covered an extreuiely interesting fact, i.e. the depen- 
 dence of the course of the disease upon the number 
 of bacteria originally introduced. He counts the 
 individual rods present in a drop of anthrax blood, 
 and estimates that from eight to ten millions are 
 congregated together in this small space. He dilutes 
 this drop of blood a million times without depriving 
 it of its lethal properties ; but he finds that although 
 the morbid material is still present, its great dilution 
 modified to a certain extent the course of the disease, 
 that whereas an animal inoculated with undiluted 
 blood succumbed to anthrax in twenty-three hours, 
 when infected with the same blood diluted, it died in 
 from forty-eight to fifty- three hours. Davaine had in 
 reality by his researches conclusively shown that the 
 blood of animals affected with anthrax could only com- 
 municate the disease when these rod-like bodies were 
 present in it, and this discovery was again confirmed 
 
134 PASTEUR. 
 
 by Klebs, who, in 1871, filtered anthrax blood through 
 porous earthenware cells, and showed that infection 
 only followed when the solid residue left on the filter 
 was inoculated, no symptoms of disease whatever 
 resulting from the injection of the blood which had 
 passed through the filter, and from which all the rod- 
 like forms had thus been removed. Davaine, how- 
 ever, even after all his brilliant researches, was unable 
 to convince the scientific world of the dependence of 
 this disease upon living rather than chemical or 
 physical processes ; and the vitalistic theory of infec- 
 tious diseases so eloquently revived by Henle already 
 in the year 1840, was destined to languish until it 
 received the support of Pasteur, who brought all the 
 forcd of his genius and indomitable energy to bear 
 upon its detractors and opponents. Davaine's re- 
 searches, moreover, at this time, had been dimmed 
 and questioned by the publication of some investiga- 
 tions made by Jaillard and Leplat, in which they 
 claimed to have repeated his experiments, to have 
 inoculated the blood of an animal certified to have 
 succumbed to anthrax into rabbits, and to have failed, 
 although inducing death, to find any symptoms of 
 anthrax or any traces of the so-called anthrax bacteria 
 in the blood. 
 
 When Pasteur entered the field in 1876, Robert 
 Koch, then a humble Krewpliysikiis in an obscure 
 part of Germany, had already announced that he, 
 likewise, had seen these rod-like forms described by 
 Davaine in anthrax blood, and had succeeded in 
 cultivating them through a number of generations in 
 blood serum and in aqueous humour, and, most 
 important of all, had observed their mode of multi- 
 
RESEARCHES ON ANTHRAX. 135 
 
 plication under the microscope, and liad seen that 
 they effected their reproduction not only by tission, 
 but also by the formation of spores, the incredible 
 vitality of which he had demonstrated by actual 
 experiment, showing — to quote his own words — that 
 they " in kaum glaublicher Art und Weise ausdauern." 
 Koch further indicated the importance of these spores 
 in the etiology of anthrax by showing that they 
 could lead to the infection of animals through the 
 alimentary tract. 
 
 But convincing as the proofs furnished byDavaine 
 and by Koch appear to us to-day, they stood in much 
 need of corroboration and extension at the time ; for 
 twenty years ago it was with principalities of prejudice 
 and with mighty powers of darkness that the new 
 views concernmg the bacterial causes of disease had 
 to contend. It required a man of Pasteur's fearless 
 originality and keen penetration to comprehend how 
 order mio-ht be created out of disorder, to discern the 
 truth which lay all but stifled under the debris piled up 
 by prejudice and misconception, to rescue this truth, 
 increase its brilliancy, and maintain it unsullied in 
 the face of adverse scientific opinion based upon 
 tradition and ignorance. To successfully accomplish 
 such a task was indeed a mission for a master mind 
 and will, and not without reason did his disciples and 
 fellow workers speak reverently of him in after years 
 as " Le Grand Maitre." 
 
 Pasteur's first efforts were directed to dispose of 
 the view so current amongst medical men that the 
 virus of anthrax was distinct from the bacilli, which 
 Davaine and Koch had laboured so zealously to 
 prove were alone responsible for the disease. " In 
 
136 PASTEUR. 
 
 anthrax blood," it was urged in the medical world, 
 " Davaine's rodlets are not alone present ; side by 
 side with them there are globules and plasma which 
 contain the real amorphous virus. The cultures of 
 Koch do not succeed in convincing us. He introduces 
 into the drop of aqueous humour which he sows with 
 anthrax blood not only bacteria, but also the virus 
 contained in the plasma, and the series of successive 
 sowings* which he carries on in drops of liquid only 
 bring about a dilution of this virus. Now, is it not 
 well known to us that the property of a virus is to 
 act in infinitely small doses, and that it may 
 be enormously diluted without losing any of its 
 activity ? " (Roux, Agenda du chimiste, 1896.) 
 
 Pasteur, like Koch, cultivates the anthrax bacilli, 
 but instead of using for this purpose single drops of 
 a culture liquid, he takes a flask containing some 
 hundreds of cubic centimetres of a sterilised organic 
 infusion such as urine rendered slightly alkaline, and 
 inoculates it with anthrax blood collected with all 
 the precautions which his previous researches had 
 shown him would ensure his obtaining it free from 
 all other organisms but those present in the blood 
 itself, i.e. the bacilli of anthrax. 
 
 Having obtained a vigorous growth of the bacilli 
 in this flask, he takes a trace of this liquid and 
 inoculates a second flask, and continues until he has 
 reached the hundredth generation. A trace of this 
 hundredth generation, he showed, induced anthrax 
 
 * Koch in his original memoir describes how he made eight 
 successive cultures from drop to drop of anthrax bacteria, and 
 the latter taken from the last or eighth generation and inoculated 
 into animals induced their death from anthrax. 
 
RESEARCHES ON ANTHRAX. 137 
 
 as readily as if a drop of the original anthrax blood 
 had been used for inoculation. 
 
 Pasteur had thus successfully disposed of the 
 objection raised to Koch's results, for here could be 
 no question of the disease being attributable to a 
 diluted yirus, for the original material employed was, 
 as compared with the volumes of culture liquid 
 into Avhich it was introduced, like a drop in the 
 ocean. No, here there could be no longer any doubt 
 that it was the work of a living ferment capable of 
 growth and self-propagation. That the disease of 
 anthrax is not due to the chemical substances which 
 are found along with the bacilli in the culture flasks, 
 but to the action of the latter alone, Pasteur further 
 showed by keeping the vessels containing the cultures 
 at a low temperature, and allowing the bacilli in 
 suspension to settle to the bottom, leaving the liquid 
 in the upper layers clear. This clear liquid inoculated 
 into animals had not the power of inducing anthrax, 
 whilst a trace of the bacillar-sediment invariably 
 ensured their death from the disease. 
 
 As is so frequently the case, in repeating and 
 perfecting the experiments of other investigators, new 
 discoveries of the highest importance are made ; this 
 was strikingly exhibited by Pasteur and Joubert in 
 the course of their studies on anthrax. It has been 
 previously mentioned {see p. 134) how Leplat and 
 Jaillard had not only questioned the results obtained 
 by Davaine, but had succeeded in exciting consider- 
 able distrust in his bacillar theory of the origin of 
 anthrax through the circumstance that the animals 
 which they had inoculated with blood derived from 
 anthrax victims had indeed been killed by the inocu- 
 
138 PASTEUR. 
 
 lation, but that not a single anthrax bacillus could be 
 found in their blood. In vain Davaine urgced that 
 the animals inoculated by Leplat and JaiHard had not 
 succumbed to anthrax but to some other disease, for 
 his efforts to find definite proofs that the disease was 
 not anthrax failed completely. The refutation was 
 left to Pasteur, who not only confirmed Davaine's 
 opinion that the disease w^as not anthrax, but suc- 
 ceeded in showing what the other disease w^as, and to 
 what it w^as due. 
 
 Pasteur made a number of examinations of anthrax 
 blood and discovered that when the latter is collected 
 immediately after the death of the animal and before 
 putrefactive processes have commenced, it contains 
 anthrax bacilli, but if some hours have elapsed since 
 the death of the animal and the collection of its 
 blood, the latter does not only contain anthrax bacilli 
 but another micro-organism, which is normally present 
 in the intestine and can onty get into the blood after 
 death. In many cases it completely overwhelms the 
 anthrax bacilli present, for it flourishes abundantly 
 in the absence of air, whilst the former cannot exist 
 without oxygen, and hence the blood of an anthrax 
 carcase frequentl}^ may contain no anthrax bacilli, 
 whilst this other anaerobic bacillus obtains complete 
 possession of the field. 
 
 Pasteur further showed with what virulent patho- 
 genic properties this bacillus was endowed when it 
 obtained access to the blood, for rabbits into which it 
 was inoculated died even more rapidly than when 
 infected with the fatal anthrax baciUi themselves. 
 
 This micro-organism, which gives rise to a deadly 
 septicaemia, is known commonly as the bacillus of 
 
RESEARCHES ON ANTHRAX. 139 
 
 malignant oedema, but it was called by its discoverers 
 — Pasteur, Joubert, and Chamberland — le vihrion 
 septique, and it was to the presence of this lethal 
 vibrio in the putrid anthrax blood employed by 
 Jaillard and Leplat that the death of their animals 
 was due. 
 
 Pasteur makes a number of most interesting 
 investigations as to the character of this new micro- 
 organism, and points out that it is an anaerobic germ 
 resembling in this particular the butyric ferment he 
 had discovered in 1861 (see p. 46) ; he ascertains also 
 that, although in its rod form it is destroyed by the 
 oxygen present in the air, it can give rise to spores, 
 which are capable of resisting the action of air. We 
 are thus presented for the first time with a pathogenic 
 anaerobic micro-organism, and the methods adopted 
 by Pasteur for its cultivation have been since employed 
 for other anaerobic micro-organisms associated with 
 disease, such as the bacillus of tetanus or lockjaw. 
 
 The memoir in which Pasteur and his assistants 
 communicated their investigations on anthrax and 
 septicsemia to the Academy of Sciences in 1877 is 
 famous not only on account of the successful manner 
 in which they mastered the etiology of these diseases, 
 but also for the extreme fertility and originality of 
 the ideas and experiments which it records. Thus we 
 have the first suggestion of the association of microbes 
 in disease, a subject which is being vigorously pursued 
 at the present day, and upon which we have by no 
 means heard the last word. Pasteur was led not only 
 to speculate but to experiment in this direction : he 
 introduces ordinary aerobic organisms into infusions 
 along with anthrax bacilli, and finds that the former. 
 
140 PASTEUR. 
 
 growing more rapidly than the latter, get possession 
 of the oxygen and consequently succeed in starving 
 their rivals. To this observation he imparts practical 
 importance by showing that " anthrax bacilli may be 
 introduced into an animal with impunity Avhen the 
 liquid inoculated contains also along with the former 
 an abundance of ordinary harmless bacteria." 
 
 Another instance of the fertility of Pasteur's ideas 
 and the prodigality of his experimental resources 
 during these classical studies on anthrax, is to be 
 found in his investigations on fowls in respect to 
 this disease. 
 
 Pasteur was confronted by the fact that although 
 he inoculated anthrax bacilli all equally virulent into 
 various kinds of animals, sorae of the latter failed to 
 develop anthrax. Thus whilst he was easily able 
 to communicate anthrax to oxen, sheep, rabbits, and 
 guinea pigs, he rarely succeeded in infecting either 
 dogs or pigs, whilst he was never able to produce the 
 disease in fowls. 
 
 To what could this failure be attributed ? Ob- 
 viously some circumstances of which Pasteur was 
 ignorant operated against the development of the 
 anthrax bacilkis in these animals. Nothing daunted, 
 Pasteur and his assistants set to work to study more 
 closely the idiosyncrasies of this microbe, or in other 
 words, the conditions which aftected its vitality in 
 artificial cultivations outside the body. These in- 
 vestigations revealed the interesting fact of the 
 sensitiveness of anthrax bacilli to even such a slightly 
 elevated temperature as is possessed by the blood of 
 fowls, and the idea immediately occurs to Pasteur of 
 artificially reducing the temperature of these birds 
 
RESEARCHES ON ANTHRAX. 141 
 
 and seeing if inoculations Avith anthrax would take 
 effect under these circumstances. A fowl was inocu- 
 lated with anthrax and subsequently made to stand 
 with its feet in cold water, so that its temperature was 
 reduced from 42 degrees C. to from 37 to 38 degrees C. 
 At the end of forty -eight hours the bird was dead, and 
 on examination its blood was found to be teeming 
 with anthrax bacilli. Another variation of the experi- 
 ment was made by infecting the fowl, reducing its 
 temperature, and then on the first sign of anthrax 
 disease making its appearance, the fowl, instead of 
 being further submitted to the cooling process, was 
 carefully wrapped in cotton wool and kept at a tem- 
 perature of 35 degrees C. Under this fostering care 
 the bird gradually regained its vitality, and when it 
 Avas completely restored to health it Avas killed, but 
 on now examining its blood not a single anthrax 
 bacillus was discovered. 
 
 An interesting confirmation of these experiments 
 in the opposite direction has been furnished by Gibier 
 in respect of the susceptibility of frogs to anthrax. 
 These amphibians are normally unsusceptible to an- 
 thrax infection, their temperature being too low to 
 admit of the growth of the anthrax bacilli within their 
 system ; but by gradually accustoming them to live 
 in warm Avater their body temperature becomes suffi- 
 ciently raised to permit of the development and multi- 
 plication of these bacilli Avithin them, and by these 
 artificial means they can be made to contract anthrax. 
 
 Engrossed Avith the interest of these pathological 
 researches Pasteur casts about him in all directions 
 for material ; he walks the hospitals armed Avith 
 sterile vessels to collect morbid products, heroically 
 
142 PASTEUR. 
 
 overcoming the natural antipathy of a sensitive nature 
 to the sight of suffering and distress ; he cultivates 
 the staphylococcvis ^pyogenes from boils on the person 
 of one of his assistants, and from its appearance and 
 character boldly asserts its identity with the organism 
 found in cases of osteomyelitis ; he visits the Maternity 
 Hospital and discovers the streptococcus pyogenes, 
 asserting it to be the cause of puerperal fever. 
 
 In connection with this discovery an instructive 
 incident is related by M. Roux. One da}^ at a dis- 
 cussion on puerperal fever which was taking place at 
 the Academy of Medicine, whilst one of the most 
 distinguished authorities was eloquently descanting on 
 the causes of epidemics of this disease at Maternity 
 Hospitals, he was suddenly interrupted by Pasteur : 
 "ce qui cause I'epidemie, ce n'est rien de tout cela; 
 c'est le medecin et son personnel qui transportent le 
 microbe d'une femme malade a une femme saine." 
 And when the speaker replied that he was much 
 afraid that they would never discover that microbe, 
 Pasteur rushed to the blackboard and drew the 
 streptococcus, exclaiming, " Tenez, voici sa figure." 
 The surprise, the stupefaction which this assurance 
 of a novice in pathological study caused amongst the 
 assembly of learned doctors, is more easily conceived 
 than described. 
 
 There can be no doubt that the great fertility 
 of Pasteur's researches in so many different depart- 
 ments of science was due to his at once seizing upon 
 the essential point of a question, and that he always 
 directed his attention to the main line of an inquiry 
 without allowing his time and energies to be frittered 
 away by side issues and considerations of secondary 
 
RESEARCHES ON ANTHRAX. 14B 
 
 importance. Thus, as we have so frequently seen, 
 whilst there was no detail insignificant enough to 
 escape his observation, yet these details were at once 
 sifted by him, and only those which were of im- 
 portance to his train of thought utilised. In fact 
 he entered the most widely different departments of 
 knowledge, not because of his special interest in them, 
 but only because the continuous course of his ideas 
 led from the one to the other. 
 
 Thus in his biological studies he was utterely 
 indifferent to the purely morphological questions in 
 which so many investigators in this branch of science 
 appear to find a permanent anchorage. He never 
 bestowed, for example, botanical names upon the 
 micro-organisms which he discovered. The microbe 
 which he isolated from boils was sufficiently endowed 
 with the title " microbe en amas de grains," whilst 
 that of puerperal fever he recognised as " microbe 
 en chapelet de grains," names which have long since 
 been exchanged for staphylococcus and streptococcus 
 pyogenes respectively. 
 
 M. Duciaux relates how an able morphologist 
 came to the laboratory one day and explained to 
 Pasteur in the most courteous terms that a particular 
 organism which the latter had described as a micro- 
 coccus was in reality a small bacillus, information 
 which only evoked the brusque reply, " Si vous saviez 
 combien cela m'est egal," a remark which very 
 clearly indicates his attitude of mind and his power 
 of dissociating the essential from the non-essential, 
 his discrimination between the things which belong 
 to nature and the things which are the outcome of 
 the vanity of man. 
 
144 PASTEUR. 
 
 Before following Pasteur into his further progress 
 in the domain of pathology, a few words are necessary 
 to convey some idea of the conditions under which 
 these and other bacteriological researches were being 
 pursued. When he first entered upon the study of 
 bacteria he was met in every direction by difficulties 
 which were occasioned through the absence of reliable 
 methods and a technique based on experience. We 
 have seen how he overcame all these obstacles, how 
 he contrived the means of procuring sterile culture 
 media, how his intimate study of bacteria induced 
 him to devise various kinds of culture materials 
 according to the individual requirements of the 
 organisms which he was handling, how he was able 
 to separate out by skilful methods numbers of 
 different varieties of yeasts and bacteria, how in fact 
 he had elaborated with his own efforts and those of 
 his assistants a complete scheme, as it were, by 
 means of which the pursuit and accurate study of 
 bacteria could be carried on. Whilst, however, 
 Pasteur by his teaching and example was stimulating 
 bacterial researches in all directions, Robert Koch 
 had still further facilitated such investigations by 
 the beautiful improvements which he had introduced 
 into microscopic technique. 
 
 In 1875, a red-letter year in the annals of 
 microscopy, Weigert discovered the method of stain- 
 ing bacteria with aniline colours, and in the hands of 
 Koch this discovery led to the most brilliant results. 
 In 1877 appeared his masterly treatise on the in- 
 vestigation, preservation, and photography of bacteria, 
 which was followed in the next year by his classical 
 investigations on the etiology of the infectious diseases 
 
RESEARCHES ON ANTHRAX. 145 
 
 of wounds. What had before been wrapped in mystery 
 or seen with difficulty was now for the hrst time placed 
 within the easy reach of every investigator ; bacteria 
 could be discovered with the greatest facility, their 
 appearance studied, and their presence in the various 
 tissues demonstrated with a precision which was alto- 
 gether unprecedented. 
 
 Robert Koch's services to bacteriology did not, 
 howcA^er, stop here; for with his name is associated 
 that great advance which introduced transparent solid 
 media for the isolation and cultivation of bacteria. 
 
 Already, as far back as the year 1872, solid media 
 had been employed by Schroeter, who observed and 
 recorded the growth and appearance on slices of 
 cooked potatoes of the bacillus prodigiosus and other 
 pigment-producing bacteria. Schroeter used also 
 white of eggs, meat, and white bread for cultivating 
 bacteria, but he does not appear to have employed 
 gelatine in any of his investigations, although un- 
 doubtedly to him belongs the credit of having first 
 isolated bacteria by means of solid culture media. 
 
 Gelatine was originally introduced for the cultiva- 
 tion of bacteria by Vittadini, Klebs, and Brefeld. 
 Klebs, in a memoir which he published in 1873, de- 
 scribes how he endeavoured to " fix " a micrococcus 
 under the microscope in order to watch its division, 
 and he relates how, in order to overcome the diffi- 
 culties, such as movement and evaporation, attending 
 the use of liquid drops, he substituted melted gelatine, 
 which solidified when cold. 
 
 Brefeld, in 1881, to continue the history of the 
 introduction of gelatine for the cultivation of bac- 
 teria, employed this material, which, he says, he 
 J 
 
146 PASTEUR. 
 
 ''■ added to culture fluids in order to prevent evapora- 
 tion." He also mentions that this addition of gela- 
 tine favoured rather than damaged the development 
 of moulds, whilst such culture material placed on 
 cover-glasses enabled the latter to be turned upside 
 down, so that the organisms present could be studied 
 with high powers. So far, therefore, the addition of 
 gelatine to culture media had been made with the 
 object of facilitating microscopic observations ; no idea 
 was entertained of separating out or isolating individual 
 bacteria by its means ; and it is to Robert Koch that 
 we owe this apparently simple but so profoundly 
 important step. Since the adaptation by Koch of 
 transparent solid media for the cultivation of bacteria 
 in 1881, and the introduction of his method of iso- 
 lating bacteria by means of gelatine plate cultures in 
 1883, the study of micro-organisms has advanced by 
 leaps and bounds, and the facilities which it has 
 offered for the examination of air and water are but 
 a few of the benefits which gelatine plate culture have 
 bestowed upon bacteriology. 
 
 * -^ * ♦ 
 
 Before leaving the classical researches of Pasteur 
 and his assistants on the etiology of anthrax, we are 
 tempted to give the reader an extract from the inter- 
 esting- account of some of the circumstances under 
 which they were carried out, which has been furnished 
 by Dr. Roux : — 
 
 " For many years the laboratory in the Rue d'UIm was 
 abandoned towards the end of July for Chartres. Chamberland 
 and I took up our abode here, and were joined by a young 
 veterinary surgeon. Every week Pasteur came to superintend 
 and to inspect our investigations. What happy memories those 
 
RESEARCHES ON ANTHRAX. 147 
 
 campaigns against antlirax in the Chartrain country have left 
 us ! The visits early in the morning to the sheep-folds scattered 
 over the great plateau of Beauce, which lay basking in the 
 August sun ; autopsies carried out at Sours or on the farms, 
 and in the afternoons the recording of the results in the note- 
 V)ook, letters to Pasteur, the starting of fresh researches. 
 
 " The day was well filled up, and how absorbing and how 
 health-giving was this bacteriology carried out in the open air ! 
 The days when Pasteur came to Chartres the dejeuner was 
 hurried over, and quick into a carriage to drive to Saint Germain, 
 where M. Maunoury had willingly placed his farm and his herds 
 at our disposal. During the drive we discussed the experi- 
 ments of the j)ast week, and planned fresh ones to be under 
 taken. As soon as he arrived, M. Pasteur hurried, withoui 
 losing a moment, to the enclosures. Motionless he would stand 
 close to the hurdles, inspecting with the minutest attention the 
 animals which were specially under observation, not a detail 
 escaping him. For hours he would watch over a single sheep 
 which he believed to be ill, and it was necessary to remind him 
 of the hour, and to point out to him that the towers of the 
 Cathedral of Chartres were fast growing dim in the dusk, 
 before we could persuade him to return. 
 
 " He would interrogate the labourers as well as the farmers, 
 and he gave much weight to the opinions of the shepherds, 
 who, in their lonely life, concentrate all their attention upon 
 their flocks and f recjuently become the most sagacious observers. 
 Nothing seemed insignificant to Pasteur ; from the smallest 
 circumstance he knew how to derive some unexpected clue. 
 
 "The original idea of the possible part played by worms in 
 the distribution of anthrax was started one day during a walk 
 he was taking in a field belonging to the St. Germain farm. 
 The harvest was over and only the stubble was left. Pasteur's 
 attention was attracted to a particular portion of the field on 
 account of the different colour of the soil. M. Maunoury ex- 
 plained that the previous year they had buried sheep which 
 had died of anthrax in that place. 
 
 " Pasteur at once went and examined the ground more closely 
 and noticed immense numbers of worm-castings scattered over 
 the surface. The idea occurred to him that these worms, in 
 
 J 2 
 
148 PASTEUR. 
 
 their repeated journeys from the depth to the top, must bring 
 up the rich soil which surrounds the carcases, and with it 
 possibly the spores of anthrax which must be present in their 
 vicinity. 
 
 " Pasteur never stopped at ideas ; he passed directly on to 
 their verification, and the germs of anthrax were actually 
 discovered in the intestines of worms, taken from a ditch in 
 which several years previously anthrax carcases had been 
 buried. 
 
 "His researches on the etiology of anthrax " (continues Dr. 
 Roux) " remain as a model. Medicine had never before 
 witnessed such perfection in experiments, such rigour in 
 deductions, such certainty in application. 
 
 " Pasteur felt indeed that a decisive battle was being fought, 
 and he neglected nothing to ensure for himself the victory." 
 
 A yet greater victory was, however, awaiting 
 Pasteur, and in a direction moreover towards which 
 he had for some time past been slowly though surely 
 drifting. 
 
CHAPTER XII. 
 
 FIRST RESEARCHES IN THE DOMAIN OF IMMUNITY. 
 
 Pasteur's mind was gradually becoming more and 
 more occupied with the idea of utilising the know- 
 ledge of viruses which he had obtained, for inducing 
 in some manner, as yet unknown to him, immunity 
 from the diseases of which these viruses were the 
 active principles. 
 
 " II faut immuniser contre les maladies infectieuses 
 dont nous cultivons les virus," was Pasteur's constant 
 cry to his assistants at this time. Haunted by this 
 idea Dr. Roux tells us how, during the busy period 
 which preceded the discovery of the attenuation of 
 viruses, numbers of impossible experiments were 
 gravely discussed amongst them, to be only laughed 
 over the following day. 
 
 In order to follow all the steps which led to this 
 truly epoch-making discovery, yet another living 
 virus, viz. that of fowl cholera, must be mentioned, 
 which Pasteur already identified in these earliest days 
 of his pathological researches. 
 
 " A bird afflicted with this malady," writes Pasteur, 
 " is weak and tottery, its wings droop, its feathers be- 
 come ruffled, giving it the appearance of a round bail. 
 It is overcome by an invincible somnolence. On being 
 forced to open its eyes it appears to be waking from a 
 profound sleep. The eyelids rapidly close again, and 
 most frequently death supervenes after a dumb agony 
 without the animal having ever moved from the spot." 
 
150 PASTEUR. 
 
 The dependence of this disease upon a micro- 
 organism was first suspected by an Alsatian veterinary 
 surgeon, whilst an Italian, one Peroncito of Turin, 
 actually described this micro-organism in 1878, and his 
 discovery was confirmed in the follow^ing year by Tous- 
 saint, a professor at the veterinary college of Toulouse. 
 
 But although this particular microbe had been 
 seen and had been seriousty suspected of being 
 responsible for this disease, the irrefutable proof of 
 its connection with fowl cholera was wanting, and 
 Toussaint, stirred up by the brilliant success of 
 Pasteur's researches on anthrax, determined to con- 
 sult the latter on the results which he had obtained 
 and to ask him to fully investigate the matter. 
 
 Pasteur eagerly embraced the opportunity thus 
 afforded to him of extending his knowledge of 
 diseases, and converted part of his laboratory into 
 what was practically a poultry-yard, and the syste- 
 matic study of this new malady was vigorously 
 pursued. Like his predecessors, Pasteur observed the 
 presence of the microbe described by them in the 
 blood of infected birds, but he w^ent a great and impor- 
 tant step farther; he succeeded in cultivating it out- 
 side the animal's body, and in artificially inducing the 
 disease in other fowls by the inoculation of such 
 cultivations. He found, moreover, that this micro- 
 organism, which is now known as the bacillus cholerce 
 gallinarum, so lethal in its effect on fowls, produced 
 only a passing and slight abscess when inoculated into 
 guinea pigs, although when taken from such abscesses 
 and again introduced into fowls it was found not to 
 have parted with one jot of its original virulence in 
 respect of the latter. The contagious character of 
 
RESEARCHES IN THE DOMAIN OF IMMUNITY. 151 
 
 this disease was farther shown by the fact that 
 healthy fowls placed in the same cage with guinea 
 pigs suffering from such abscesses became infected 
 and rapidly succimibed to fowl cholera. Pasteur dis- 
 covered in this manner that rabbits were also 
 extremely sensitive to the lethal action of this 
 microbe, and some ten years later he utilised this 
 fact in suggesting to the Government of New South 
 Wales that the Australian rabbit plague should be 
 combated by the artilicial dissemination of this 
 bacterial virus amongst these destructive rodents. 
 The suggestion was not accepted by the Government, 
 chiefly on account of the reluctance which was felt to 
 introduce what, at that time, was looked upon as a 
 new disease into the colony. The idea, however, has 
 recently been revived, as it has been since discovered 
 that fowl cholera has existed there for many years 
 past, its presence having been formerly ignored, owing 
 to imperfect knowledge of the nature of the disease 
 and inability to diagnose it in afflicted birds. 
 
 But this year, 1880, which had thus seen another 
 disease tracked to its source, which had thus furnished 
 new important evidence as to the vital cause of con- 
 tagious disease, was also to witness a discovery, the 
 far-reaching application of which we are only now 
 beginning to appreciate, and which has opened up an 
 entirely new field of investigation, and promises to 
 change the whole aspect of modern medicine. 
 
 This great discovery was the attenuation of virus 
 and the artificial production of immunity, and was 
 led up to by one of those events which when occurring 
 singly appear as wholly the work of chance, but which, 
 when recurring again and again in connection with 
 
152 PASTEUR. 
 
 one and the same individual, are the most un- 
 mistakable evidence of genius. 
 
 The investigations on fowl cholera had been com- 
 menced in the year 1879, and had been vigorously 
 and uninterruptedly pursued until they had to be 
 temporarily suspended owing to the vacation. All 
 who have seriously worked with bacteria must have 
 experienced the difficulties which stand in the way of 
 taking any prolonged holiday. To the chemist the 
 vacation often comes as a welcome assistant in his 
 researches ; refractory oils and unpromising syrups, 
 Avhich are set aside almost in despair at the end of 
 the term, often greet us on our return to work with 
 crystalline forms which gladden the eye and make 
 the heart beat with redoubled vigour at the prospect 
 of renewing our labours ; but the bacteriologist returns 
 after a hardly earned holiday only to find that the 
 cultivations, which have perhaps taken him months 
 or even years to obtain, are either languishing or even 
 defunct through the want of that maternal solicitude 
 which he was wont to lavish on them, or that they 
 have suffered contamination while consis^ned to the 
 stepmotherly care of some unworthy assistant. 
 
 On the reopening of the laboratory, the dismay of 
 Pasteur may be imagined when he found that nearly 
 all his cultures had in the interval died off' or become 
 sterile. Numerous efforts were at once made to revive 
 those which still showed signs of life ; they were 
 transplanted into fresh culture material, and fowls 
 were inoculated, but in many cases no evidence of 
 life was displayed in the tubes, and the animals re- 
 mained provokingly healthy. There seemed to be 
 no alternative but to discard all the old series of 
 
RESEARCHES IN THE DOMAIN OF IMMUNITY. 153 
 
 cultures and start de novo, when the idea occurred 
 to Pasteur to infect these same fowls, which had so 
 effectually resisted the previous inoculations, with a 
 young and vigorous growth of the microbe. To the 
 astonishment of all, Pasteur included, nearly all these 
 fowls survived the inoculation, whilst other fowls, 
 similarly infected, but which had not previousl}^ been 
 experimented upon with the weakened cultures, died, 
 exhibiting the usual typical symptoms of the disease. 
 Convinced that this Av^as no chance circumstance, but 
 that he was here face to face with an entirely new 
 phenomenon, Pasteur repeated the experiment in 
 various ways, and found that he had indeed reahsed 
 his great ambition of " immunising against an infec- 
 tious disease of which they cultivated the virus," and 
 the microbe, which hitherto had only proved a malig- 
 nant foe, was constrained to become the beneficent 
 protector of its prey. 
 
 Numerous investigations were now carried out to 
 ascertain upon what factors this conversion of the 
 virus into a vaccine was dependent, and before long 
 Pasteur Avas able to announce the methods by which 
 this transformation could be effected with certainty. 
 The secret lay in the prolonged action of the air upon 
 the culture at a suitable temperature. Whereas, a 
 young growth of the microbe is extremely lethal 
 in its action, if it be kept at a temperature of 37 
 degrees C. in a tube plugged with cotton wool, to 
 which, therefore, air has free access, it gradually loses 
 its virulence in proportion to the length of time it is 
 preserved under these conditions. If, on the other hand, 
 the cultivation is carried on in a closed tube from which 
 air is excluded, it will retain its virulent properties. 
 
 Pasteur also discovered that this attenuated or 
 
154 PASTEUR. 
 
 weakened fowl-cholera virus retained its modified 
 character in subsequent generations, that this protec- 
 tive power or immunising property was transmissible 
 or hereditary. By suitable cultivation a permanently 
 modified race of bacilli had been raised, and we shall 
 see later how this principle was applied for the 
 elaboration of other vaccines. With what confidence 
 and rejoicing this great discovery of Pasteur's was 
 received by the Academy of Sciences we may judge 
 by the spontaneous eloquence of a member who was 
 present when the communication was made. " Ce 
 n'est la qu'un commencement, line doctrine nouvelle 
 s'ouvre pour la medecine, et cette doctrine m'apparait 
 puissante et lumineuse. Un grand avenir se prepare; 
 je I'attends avec la confiance' d'un croyant et le zele 
 d'un enthousiaste." 
 
 It was in 1881, on the occasion when the Inter- 
 national Medical Congress met in London, that Pasteur, 
 discussing his latest discoveries in the domain of im- 
 munity, paid a graceful tribute to his great predecessor 
 nearly a century before him, in this direction: "J'ai 
 prete a I'expression de vaccination une extension que 
 la science, je I'espere consacrera comme un hommage 
 au merite et aux immenses services rendus par un 
 des plus grands hommes de I'Angleterre, Jenner." 
 
 Pasteur's attention, indeed, had long been riveted 
 on that great achievement of Jenner's which towers 
 in royal isolation above the plains of the medical 
 history of centuries, an achievement which, as Herbert 
 Spencer has pointed out, a grateful country has, up 
 to the present, rewarded by a begrimed statue hidden 
 away in an obscure corner of Kensington Gardens, 
 frequented chiefly by nursemaids and perambulators. 
 
CHAPTER XIII. 
 discovf:ry of anthrax vaccine. 
 
 From this tiiiio onwards Pasteur's attention became 
 riveted upon the artiticial production of attenuated 
 viruses or vaccines. Stimulated and encouraged by 
 the extraordinary piece of good fortune which, as we 
 have seen, had hiunched him on his first voyage into 
 those regions which had so long appeared only as the 
 shadowy illusions of a vivid imagination, he now set 
 to work with all his customary zeal and enthusiasm 
 to prepare the vaccine of anthrax. 
 
 The virus, we have seen, was to hand ; for months 
 past Pasteur and his assistants had been busily en- 
 gaged in studying its character, and it was only 
 natural, therefore, that this disease should be the next 
 to furnish material for further investigations on the 
 artificial production of immunity. 
 
 At the very outset, however, the experiments met 
 with a serious check from the fact that the virus of 
 anthrax differs in a very important particular from 
 that of chicken cholera. We have seen that to 
 elaborate a vaccine in the case of the latter disease, it 
 was only necessary to allow the bacterial cultures to 
 age considerably in the presence of air; but this simple 
 method was found to be quite inapplicable to anthrax, 
 for this micro-organism, unlike the bacillus of fowl 
 cholera, multiplies not only by fission, but also by the 
 production of spores. 
 
 Now, the preservation of anthrax cultures over 
 
156 PASTEUR. 
 
 prolonged periods of time neither weakens nor destroys 
 these spores, so that the virus after ageing has lost 
 nothing of its virulence. 
 
 It was obvious, therefore, that the method so 
 simple and effective in the case of fowl-cholera virus, 
 could not be applied without important modifications 
 to the attenuation of the virulence of anthrax cultures. 
 Pasteur then planned a scheme of experiments based 
 upon the assumption that in its simple bacillar form 
 anthrax would be as sensitive as the bacilli of fowl 
 cholera to those conditions of environment which had 
 so profoundly modified the virulence of the latter. 
 
 " Let us find out how to prevent the corpuscular 
 germs (spores) of anthrax from being produced," 
 argued Pasteur, "and we shall have surmounted the 
 difficulty ; for once freed from these corpuscular 
 germs, the anthrax threads (bacilli) can be kept in 
 contact with air during a given time, and we shall then 
 have possibly secured the conditions which led to the 
 attenuation of the fowl-cholera microbe." 
 
 Innumerable were the experiments which Pasteur 
 and his two assistants, Chamberland and Koux, carried 
 out. Pasteur became more and more pre-occupied, 
 and wore that air so familiar to those around him, 
 and which his daughter used to designate as " la 
 figure a decouverte prochaine " — a state of mind of 
 intense nervous tension and excitement, which, how- 
 ever, was only evident to those in his immediate 
 surroundings by his abstraction and silence, a con- 
 dition which has again been well described in the 
 following graphic manner by Dr. Roux : — 
 
 " Of Pasteur it may be said that he has made his 
 discoveries by continually thinking over them. His 
 
DISCOVERY OF ANTHRAX VACCINE. 157 
 
 thoughts attached themselves obstinately to the diffi- 
 culties, and ended by solving them, just as the intense 
 flame of a blowpipe constantly directed upon a refrac- 
 tory substance ends by melting it. During these 
 moments of great pre-occupation Pasteur remained 
 silent, even in his own family circle. Nothing was 
 able to smooth the determined lines in his face until 
 the solution was found. Then his countenance became 
 illumiaated, and this reserved man allowed his joy to 
 overflow, around him, and he described what he had 
 planned and what he hoped. For Pasteur's surround- 
 ings were associated with his scientific life ; they sub- 
 mitted to the contre-coup of his pre-occupations and 
 shared in the rejoicing of the savant." 
 
 At length the day arrived when, hastily leaving 
 the laboratory, he announced to his family the success 
 which had at length crowned the long and patient 
 labours which had cost him so much mental and 
 physical strain — the discovery of a vaccine for an- 
 thrax. "Jamais," writes his son-in-law, M. Vallery- 
 Radot, referring to this incident, "je n'ai vu sur une 
 physionomie un plus grand rayonnement de toutes les 
 emotions hautes et genereuses que peut contenir 
 Tame humaine." 
 
 But even at these moments of supreme scientific 
 triumph the patriotic sentiment asserted itself, and 
 showed what a large place it occupied in the savant's 
 heart ; for says the same family biographer : " ' Je ne 
 me consolerais pas,' nous dit-il en nous embrassant, 
 ' si une decouverte comme celle que nous venons 
 de faire, mes preparateurs et moi, n'etait pas une 
 decouverte fran9aise ! ' " 
 
 By cultivating anthrax in the presence of air at 
 
158 PASTEUR. 
 
 42 degrees to 43 degrees C. it does not form spores. It is 
 found, after being kept for two, four, six, or eight days, 
 to have abated its original virulence according to the 
 length of time it has been preserved in these unfavour- 
 able conditions, thus affording a series of vaccines of 
 different degrees of strength. These attenuated anthrax 
 bacteria retain, moreover, their enfeebled character in 
 subsequent generations, and thus the production of a 
 graduated series of attenuated vaccines offers no diffi- 
 culty and becomes a mere matter of laboratory routine. 
 
 Thus to confer immunity from anthrax it is only 
 necessary to select from the series of vaccines one 
 which, whilst sufficiently virulent to induce a passing 
 manifestation of the disease, is not strong enough 
 to destroy the animal, and yet by reason of the 
 modified symptoms engendered suffices to protect 
 the latter from the subsequent lethal effects of anthrax 
 virus possessing its full complement of toxicity. 
 
 In actual practice it is customary to make two 
 vaccinations at an interval of twelve days, the first 
 with a very weak virus, the second with a stronger 
 virus which completes the immunity. 
 
 It was on the 28th of February, 1881, that Pasteur 
 communicated to the Academy of Sciences, in his own 
 name and in . that of Chamberland and Roux, the 
 famous memoir on the attenuation of anthrax virus ; 
 and hardly had the results been made known when 
 Pasteur was approached by the President of the 
 Agricultural Society of Melun, with a view to the 
 organisation of a public demonstration of the value 
 attaching to these new protective methods. Pasteur 
 gladly accepted the challenge, and the details of the 
 programme to be followed were drawn up and 
 
DISCOVERY OF ANTHRAX VACCINE. 159 
 
 arranged between him and the Mekm Agricuhural 
 Society just two months after he had tirst communi- 
 cated his results to the French Academy. 
 
 Dr. Eoiix has described the details of this remark- 
 able performance, in w^hich he took a prominent part, 
 In such a vivid manner that we cannot do better 
 than quote the account of it wdiich he has given. 
 
 " Chamberland and I were on our holidays. Pasteur wrote 
 to us to return immediately, and when we were once more 
 together in the laboratory, he gave us an account of what had 
 been agreed upon. Twenty-five sheep were to be vaccinated 
 and afterwards inoculated with anthrax at the same time as 
 twenty-five non-vaccinated sheep ; the first set would resist 
 infection, the second would succumb to anthrax. The terms were 
 precise, no place was reserved for the unexpected. When we 
 remarked that the programme was a severe one, but that there 
 was nothing left but to carry it out since it was signed, Pasteur 
 replied : ' What has succeeded with fourteen sheep in the 
 laboratory, will succeed equally well with fifty at Melun.' The 
 animals were brought together at Pouilly-le-Fort, near Melun, 
 on the estate of M. Rossignol, a veterinary surgeon, who first 
 originated the idea of the experiment, and who was entrusted 
 with its superintendence. ' Above all do not get your flasks 
 mixed up,' said Pasteur gaily, when on the 5th of ^lay we left 
 the laboratory to make the inoculations with the first vaccme. 
 Those with the second vaccine were carried out on the 17th 
 May, and every day Chamberland and I went to inspect the 
 animals. 
 
 " During these journeys from Melun to PouiUy-le-Fort, 
 many remarks came to our ears which showed that it was not 
 everyone who believed in the success of the undertaking. 
 Agriculturists, veterinary surgeons, doctors, followed the ex- 
 periment with the greatest interest, some even with feelings 
 of the keenest excitement. 
 
 "In 1881, the science of microbes had hardly any partisans 
 many considered the new doctrines as pernicious,and the fact that 
 Pasteur and his assistants had been drawn beyond the precincts 
 
160 PASTEUR. 
 
 of the laboratory was regarded as an unexpected opportunity 
 for their open discomfiture in a public trial. These novelties 
 so compromising for medicine would be swept away at one 
 stroke, and the safety of wholesome traditions and ancient 
 practices, menaced for a moment, would be restored ! 
 
 " In spite of all the passion and prejudice which surrounded 
 it, the trial followed its course. The experimental inoculations 
 were made on the 31st ^lay, and a meeting was arranged for 
 the 2nd June for the verification of the results. 
 
 " Twenty-four hours before the decisive day, Pa.steur, who 
 had anticipated the public trial with such perfect confidence, 
 began to regret his boldness. For a few moments his faith 
 wavered, as if the experimental method might betray him. A 
 too continuous mental tension had brought about this reaction, 
 which, however, did not last long. The following day, more 
 confident than ever, Pasteur was able to confirm the brilliant 
 success which he had predicted. In the eager crowd assembled 
 that day at Pouilly-le-Fort, there were no more unbelievers, 
 only admirers." 
 
 The immediate result of this magnificent triumph 
 was a pressing demand from all parts of the country 
 for vaccine, numerous agricultural societies were fired 
 with ambition to repeat the celebrated experiment of 
 Pouilly-le-Fort, and Pasteur was besieged with cor- 
 respondence. A small additional laboratory was 
 hastily improvised where the preparation of vaccines 
 was carried out, and already by the end of the year 
 no less than 33,946 animals had been vaccinated. 
 
 The burden of w^ork which all this meant for 
 Pasteur may be imagined, as he personally superin- 
 tended the production of the vaccine and its dispatch 
 to its various destinations, whilst he invariably fol- 
 lowed the course of the inoculations, which alone 
 involved a mass of letters dealing with the various 
 details of the process, replying to complaints, and 
 
DISCOVERY OF ANTHRAX VACCINE. 161 
 
 answering adverse critics, amongst whom in those 
 days were ranged Koch and Loeffler. 
 
 In spite, however, of prejudice and hostile opinion, 
 the protective inoculation against anthrax grew more 
 and more in public favour, and in a report drawn up 
 by Chamberland in 1894, who, after the first demon- 
 stration at Pouilly-le-Fort, was made responsible by 
 Pasteur for the production of the vaccine, we learn 
 that in the preceding twelve years 3,296,815 sheep 
 were vaccinated, with a mortality of about one per 
 cent., and 438,824 oxen and cows, with a mortality of 
 about 0"34 per cent. 
 
 The mean annual mortality from anthrax amongst 
 sheep not vaccinated is given in France as 10 per 
 cent., and amongst horned cattle 5 per cent. 
 
 Chamberland in his report further points out that 
 the saving to French agriculture which has accrued 
 from the use of Pasteur's vaccine may be estimated as 
 at least five millions of francs with regard to sheep 
 and two millions in respect of oxen and cows. 
 
 But, as Dr. Roux has well said, the immediate re- 
 sults are the least merit of the Pasteurian vaccinations; 
 they have imparted an immense public confidence in 
 the science which has achieved such great triumphs 
 and aroused so much interest. Above all, they have 
 inaugurated that series of researches on immunity 
 which at last is leading us towards an efficacious 
 therapy for infectious diseases. 
 
 Pasteur, however, having succeeded in artificially 
 controlling the degree of virulence possessed by 
 anthrax and fowl cholera cultures, set to work to 
 ascertain whether and to what extent such attenuated 
 races of bacteria could be re-endowed with lethal 
 
 K 
 
162 PASTEUR. 
 
 properties. The short note which contains the account 
 of these most original and suggestive investigations 
 was communicated to the Academy of Sciences early 
 in the year 1881, and bears also the names of Roux 
 and Chamberland. 
 
 Although anthrax reduced to the condition of a 
 vaccine is incapable of procuring the death of an adult 
 animal, yet if these weakened anthrax bacilli be in- 
 oculated into extremely susceptible animals, such as 
 mice and guinea-pigs but one day old, the latter suc- 
 cumb to its action, and the blood of these animals 
 introduced into rather older mice and guinea-pigs 
 succeeds also in fatally infecting these, and so on until 
 the stage has been reached, when, through the suc- 
 cessive passage of the virus through the bodies of 
 animals, the original attenuated race of anthrax bacilli 
 has regained its full complement of virulence and can 
 once more destroy large animals, such as sheep and oxen. 
 
 Similar results were obtained with the vaccine or 
 weakened bacilli of fowl-cholera, their lethal effects on 
 fowls themselves being gradually restored by passing 
 the attenuated microbes through the bodies of small 
 birds, such as sparrows, canaries, and pigeons, until 
 their virulence was fully regained and fowls once 
 more fell victims to their action. 
 
 Pasteur points out that what has thus been suc- 
 cessfully accomplished in the laboratory may not 
 unreasonably be conceived to take place in nature — 
 that just as the action of the atmosphere may weaken 
 a virus and so bring about the extinction of an epi- 
 demic disease, so the impression of virulence upon an 
 otherwise harmless microbe by its passage through 
 the system of an animal, or by other means yet 
 
DISCOVERY OF ANTHRAX VACCINE. 163 
 
 unknown to us, may possibly account for the origin, 
 in past ages, of infectious diseases. 
 
 J3ut besides increase of virulence we may also 
 obtain diminution of virulence by passing the virus 
 through the bodies of suitable animals, and this was 
 done by Pasteur and Thuillier in the course of their 
 investigations on the disease known as swine measles 
 or rouget des pores. By successively passing the virus 
 of this disease on from pigeon to pigeon the virulence 
 is so greatly augmented towards these animals, that 
 they succumb far more rapidly to its effects than when 
 the virus is taken direct from a pig suffering from the 
 disease ; moreover, this pigeon-treated virus is even 
 more rapidly fatal to pigs than in its original condition. 
 
 If, however, instead of pigeons, rabbits be employed, 
 the virus instead of increasing in virulence becomes 
 less fatal in its effects, until finally it is incapable of 
 killing pigs, and only renders them ill, leaving them, 
 however, vaccinated against a fatal attack of the disease. 
 
 We shall see later how Pasteur utilised these 
 principles in the methods he was led to adopt for 
 the attenuation of another virus. 
 
 In connection with the researches on swine 
 measles published in conjunction with Thuillier, a 
 young, extremely able and enthusiastic student and 
 assistant of Pasteur's, we find a pathetic little com- 
 munication from Pasteur a couple of years later to 
 the Academy announcing his death : " La science 
 perd en Thuillier un de ses courageux representants 
 et du plus grand avenir. Je perds un disciple aime 
 et devoue, mon laboratoire un de ses principaux 
 soutiens. Je ne me consolerai de cette mort qu'en pen- 
 sant knotre chere patrie et a ce qu'il a fait pour elle." 
 
CHAPTER XIV. 
 
 RABIES. 
 
 It must not be supposed that, absorbing and laborious 
 as these investigations on vaccines were, they repre- 
 sent by any means the whole extent of Pasteur's 
 activity at this time, for simultaneously experiments 
 were being carried on in quite another direction, the 
 study of hydrophobia having been already commenced 
 in the year 1880. 
 
 In extending his beneficent investigations to the 
 study of rabies, Pasteur thus finally devoted his 
 energies to combating disease in man himself. These 
 last labours, moreover, display in the highest degree 
 those remarkable qualities which had characterised 
 his whole career, and for the performance of these 
 labours the powers and experience gained during 
 nearly forty years of ceaseless scientific activity were 
 called into requisition and submitted to the severest 
 strain. 
 
 It has appeared a most unaccountable circum- 
 stance to many that in approaching the diseases of 
 man Pasteur should have made the selection which 
 he did in taking hydrophobia as the first human 
 malady to which he was determined to apply those 
 prophylactic measures Avhich had been found so 
 successful in combating some of the diseases of 
 animals. Thus, terrible as hydrophobia may be to the 
 
RABIES. 165 
 
 individual affected, it is of little absolute importance 
 to the human race as a whole, claiming as it does 
 perhaps a smaller number of victims annually than 
 almost any other well-recognised malady. 
 
 In making this selection Pasteur was doubtless 
 guided by that instinct which leads the experimental 
 genius to choose those subjects of research which are 
 ripest for attack at the time, and quite irrespectively 
 of their immediate practical importance to the world 
 in general. Experience has, in fact, fully justified the 
 selection of this comparatively obscure human disease 
 as the one on which to make the first assault with 
 the scientific weapons which his researches on fowl- 
 cholera and anthrax had created. 
 
 The wisdom of Pasteur's selection doubtless 
 depends on rabies being a well-defined disease in both 
 animals and man, and that it can therefore be fully 
 investigated by direct and real experiment on animals, 
 and not merely by those statistical methods which 
 have in general to pass muster as experiments in 
 medicine. 
 
 We venture to think that there is the more force in 
 these remarks from the fact that so much success has 
 attended this attack on hydrophobia, in spite of our 
 being even still in complete darkness as to the real 
 nature of the exciting cause of the disease ; for not 
 only has, up to the present day, the microbe of rabies 
 remained undiscovered,, but it is not even known 
 with certainty whether it is a microbial disease at all. 
 At the very threshold of this investigation, then, 
 was the obstacle of the exciting cause of the disease 
 being unknown, and although this obstacle still 
 remains, it has no more blocked the way to the 
 
166 PASTEUR. 
 
 discovery of preventive measures than did the same 
 obstacle in the case of small-pox so many years 
 before. 
 
 The fact that rabies is transmissible from animal 
 to animal and from animals to man, not unnaturally 
 led Pasteur and his assistants to believe that they had 
 in this virus an active agent probably resembling in 
 character the other viruses which had been so success- 
 fully tracked out by them, and there seemed every 
 justification in presuming that here again they had to 
 reckon with a bacterial transmitter of disease. 
 
 But, in spite of the most laborious microscopic 
 examinations, and the application of all the subtlest 
 devices for the staining and cultivation of bacteria, 
 as has been already mentioned, the microbe of rabies 
 has until now successfully eluded all attempts at its 
 detection. It would be impossible to enuuierate the 
 countless cultivations and experiments which were 
 made with the saliva of rabid animals in the hope of 
 isolatinsf the bacterium of rabies, nor the host of in- 
 oculations carried out to secure the artificial infection 
 of animals with rabies. 
 
 That Pasteur did not despair in the presence of 
 such overwhelming difficulties can only be attributed 
 to the fact that " la genie c'est la patience," and it was 
 the possession of such unconquerable energy and de- 
 termination which enabled Pasteur to calndy encourage 
 his assistants when on the brhik of despair by saying : 
 " Refaisons la meme experience, I'essentiel est de ne 
 pas quitter le sujet." 
 
 The important step to be secured was the discovery 
 of a method whereby rabies could be with certainty 
 communicated to an animal. Inoculations in the 
 
RABIES. 167 
 
 first instance were invariably made with the saliva 
 obtained from a rabid animal, and every case of 
 hydrophobia in Paris was at once notified to 
 Pasteur. 
 
 It is not often that the scientific man of to-day 
 has an opportunity of displaying personal courage, 
 but the vivid description given by M. Vallery-Radot 
 of how he accompanied Pasteur on one of his expe- 
 ditions to inspect a rabid dog and collect its saliva, 
 shows that Pasteur had inherited the same fearless 
 elan which had doubtless gained for his father the 
 decoration on the field of battle. They started, taking 
 six rabbits with them in a basket. The rabid beast 
 was in this case a huge bull-dog, foaming at the mouth 
 and howling in his cage. All attempts to induce the 
 animal to bite, and so infect one of the rabbits, failed ; 
 "but we nvust," said Pasteur, " inoculate the rabbits 
 with this saliva." Accordingly, a noose was made and 
 thrown, the dog secured and dragged to the edge of 
 the cage, and his jaws tied together. Choking with 
 rage, the eyes bloodshot, and the body convulsed by 
 a violent spasm, the animal was stretched on a table, 
 and kept motionless whilst Pasteur, leaning over this 
 foaming head, sucked up into a narrow glass tube some 
 drops of the saliva. 
 
 Actions such as these should make the British 
 public remember that there are some who, in the 
 obscurity of the laboratory, exhibit the same heroism 
 which is rewarded by the Victoria Cross when dis- 
 played on the veldt of South Africa or in the passes 
 of Afghanistan. 
 
 Unfortunately, however, inoculations made with 
 the saliva of rabid animals did not invariably produce 
 
168 PASTEUR. 
 
 hydrophobia, and even when they succeeded, the 
 symptoms frequently did not declare themselves for 
 months. This method had, therefore, to be abandoned; 
 and as it was evident that rabies was essentially a 
 disease affecting the nervous system, it was thought 
 probable that the virus was located in the nerve 
 centres of the body — a' suggestion already made by 
 Dr. Duboue, of Pau. 
 
 Experience soon verified the truth of this hypo- 
 thesis, for nervous tissue inoculated subcutaneously 
 into an animal did excite rabies. But even this mode 
 of infection proved in practice hardly more reliable 
 than had the saliva inoculations, and so far, in spite 
 of all efforts, no trustworthy means of transmitting 
 rabies with certainty and within a reasonable time 
 had been discovered. 
 
 Now, however, an important departure was made. 
 Bearing in mind the fact that the seat of the disease 
 in rabies is located in the nervous centres, Pasteur 
 conceived the idea of communicating it by taking the 
 nerve tissue of an animal which had died of rabies 
 and introducing it into the central nervous system — 
 the brain — of the animal to be infected. 
 
 This mode of procedure, it should be pointed out, 
 was not based on any pathological considerations, but 
 was simply an adaptation of the principle which 
 Pasteur had followed in all his researches both on 
 fermentative and other micro-organisms — namely, to 
 provide for each microbe that nutritive medium which 
 was best suited to its particular requirements. To 
 Pasteur, therefore, the nervous tissue of the rabid 
 animal appeared as a pure cultivation of the rabies 
 virus, and in this material he now endeavoured to 
 
HABIES. 169 
 
 induce attenuation on the lines which had proved so 
 effective in the case of fowl-cholera and anthrax. 
 
 " Usually," Dr. Roux tells us, "when an experiment 
 was planned it was carried out without delay ; but this 
 one, from Avhich we anticipated so much, was not at 
 once put in operation. Pasteur, although obliged to 
 sacrifice so many animals in the course of his benevo- 
 lent researches, had a real repugnance to vivisection. 
 He took part in a simple operation, such as a subcu- 
 taneous inoculation, without much distress, but if the 
 animal cried out a little, Pasteur was at once full of 
 pity for it and gave the victim sympathy and en- 
 couragement which would have appeared comic 
 had it not been touching. 
 
 " The idea of perforating the skull of a dog was 
 repulsive to him. He ardently desired that the 
 experiment should be carried out, but he dreaded 
 seeing it done. 
 
 " I did it one day when he was absent. The next 
 day when I informed him that the intra- cranial in- 
 oculation offered no difficulty, he was moved with 
 pity for the dog. ' Poor beast ! his brain is doubtless 
 injured : he must be paralysed.' Without replying, I 
 went down to the basement to fetch the animal and 
 let it come into the laboratory. Pasteur did not like 
 dogs, but when he saw this one, full of life, inquisitively 
 rummaging about in all directions, he exhibited the 
 greatest delight, and lavished most charming words 
 upon him. 
 
 " Pasteur was infinitely grateful to this dog for 
 having borne the trepanning so well, and thus causing 
 all scruples as regards such operations in the future 
 to disappear. 
 
170 PASTEUR. 
 
 " This first trej)anned dog exhibited characteristic 
 rabies in fourteen days. The experiment repeated 
 many times gave the same results : it was thus possible 
 to communicate rabies with certainty and in a rela- 
 tively short time ; after that it was easy to experiment. 
 
 " The inoculation of the virus by trepanning succeeds 
 also in the case of rabbits, and it is easy to transmit 
 in this manner rabies from rabbit to rabbit. In the 
 course of these successive passages of the virus the 
 latter increases in virulence, and the time of incubation 
 is diminished until it lasts no longer than six days. 
 In this way the virus of rabies was actually cultivated 
 within the skull. Instead of carrying on the cultiva- 
 tions as in the case of other viruses in artificial media, 
 the virus of rabies is cultivated in living material. 
 These cultures in nerve tissue can be modified just as 
 the culture of anthrax or fowl-cholera. 
 
 " Rabid marrows, exposed to the action of the air, 
 in a dry atmosphere become desiccated and lose their 
 activity. After fourteen days the virus is attenuated 
 to such an extent that it is harmless, even in the 
 largest doses. A dog receiving this fourteen-days-old 
 marrow, then on the following day thirteen-days 
 marrow, then that of twelve days, does not take rabies, 
 but has become immune to it. Inoculated in the eye 
 or in the brain with the strongest virus, it remains well. 
 In fifteen days, therefore, it is possible to confer 
 immunity upon an animal from rabies. Now, human 
 beings bitten by mad dogs do not usually develop 
 rabies until a month or even longer after the bite. 
 This time of incubation can be utilised to render the 
 person bitten refractory." 
 
 In these few concise words Dr. Roux has sum- 
 
RABIES. 171 
 
 marised the results of years of work, and still the 
 most difficult, the most perilous task remained to be 
 accomplished — the application of the knowledge and 
 experience thus acquired to the prevention of rabies 
 in man. This momentous step was taken by Pasteur, 
 encouraged by the support of Vulpian and assisted 
 by Grancher. 
 
 Dr. Grancher, who undertook the onerous task of 
 performing the inoculations, was already distinguished 
 in his profession when he entered Pasteur's laboratory 
 to hll up, as he said, a blank in his scientific educa- 
 tion. 
 
 The first human being to undergo the treatment 
 was a young boy from Alsace. It was in July, 1885, 
 that Joseph Meister arrived in Paris, his body literally 
 covered with wounds from the bites of a rabid dosr. 
 Vulpian and Grancher both urged Pasteur to apply 
 his treatment to this poor child, whose life already was 
 so seriously threatened, and Pasteur, yielding to their 
 solicitations, gave his consent. 
 
 As, however, the series of inoculations drew to a 
 close, Pasteur became terribly uneasy. He passed 
 days of anxiety and sleepless nights, and was a prey 
 at once to the wildest hopes and to the most cruel fits 
 of depression. 
 
 Meister returned to Alsace on the 27th of July, 
 and was instructed to supply Pasteur with a daily 
 bulletin of his health. With the forgetfulness, how- 
 ever, of a child, often five or six days would pass 
 without any news of him reaching the laboratory, and 
 Pasteur suffered torments of anxiety. On being 
 reproached by Pasteur for his long silence on one of 
 these occasions, the lad wrote towards the end of 
 
172 PASTEUR. 
 
 August : " It is indeed ungrateful in me not to send 
 you news of how I am, since you, my dear Monsieur 
 Pasteur, are so concerned about my health. I thank 
 you, as also do my parents, a thousand times. It is 
 with delight that I tell you that I am well and eat 
 well." 
 
 It was on the 26th October, 1885, that Pasteur 
 commimicated that celebrated memoir to the Acadejiiy 
 of Sciences in which he described the results of what 
 he modestly designated a " tentative heureuse." A 
 profound impression was produced by this successful 
 result, and true indeed were the words with which 
 his colleagues greeted this great achievement : " Ce 
 nouveau travail met le sceau a la gloire de M. 
 Pasteur et jette un eclat incomparable sur notre 
 pays." 
 
 Wounded persons soon streamed in from all parts, 
 the laboratory becoming transformed into a veritable 
 clinic, and the resources of the staff were taxed to the 
 utmost during the next year to keep pace with the 
 inoculations alone, as many as 2,682 individuals being 
 treated, each of whom, on an average, received between 
 fifteen and twenty inoculations. 
 
 Nearly 20,000 persons have now undergone 
 Pasteur's anti-rabic treatment at the Paris Institute, 
 and the mortality has been less than 5 per 1,000. 
 
 But this magnificent triumph was not easily 
 secured. At the time when Dr. Grancher first accepted 
 the responsibility of conducting the inoculations, one 
 of Pasteur's most determined opponents — M. Peter — 
 reiterated his request to the Academy of Sciences 
 almost Aveekly, that they should order the laboratory 
 in the Rue d'Uhn to be closed, where, he declared, 
 
RABIES. 173 
 
 instead of curing rabies they were, in reality, com- 
 municating the disease."^ 
 
 Tempora mutantur ! On the outer walls of this 
 same laboratory, now known as the Pasteur La- 
 boratory and occupied by the Ecole Normale, the 
 Municipal Council of Paris have recently (1897) placed 
 a bronze medallion of Pasteur. It surmounts a slab 
 of black marble bearing in letters of gold the following 
 inscription : 
 
 ICI PUT LE LABOUATOIRE DE PASTEUR 
 
 1857.— Fermentations. 
 
 1 800.— Generations spontan^es. 
 
 "1805. — Maladies des vins et des bieres. 
 
 1868.— Maladies des vers 1 soie. 
 
 1881.— Virus et vaccins. 
 
 1885.— PROniYLAXIE DE LA RAGE. 
 
 It was amidst the most determined opposition at 
 home and abroad that Pasteur had to fioht over two 
 
 o 
 
 years for the pubhc recognition of this great discovery, 
 
 * In this country public opinion was so divided as to the value 
 attaching to the new treatment, that the Local Government Board 
 was induced to take up the matter, and in April, 1886, at Sir Henry 
 Roscoe's suggestion, a committee was aj)pointed to inquire into the 
 efficacy of Pasteur's methods, and into any dangers which might be 
 connected with their application. The committee was a representa- 
 tive one, and consisted of Sir James Paget (Chairman), Dr. Lauder 
 Brunton, Dr. George Fleming, Sir Joseph Lister, Dr. Richard Quain, 
 Sir Henry Roscoe, Professor J. Burden Sanderson, and Professor Victor 
 Horsley. Professor Horsley, who acted as secretary, subsequently 
 visited Paris in company with Dr. Brunton, Sir Henry Roscoe, and 
 Professor Sanderson, in order to study Pasteur's methods on the spot. 
 Numerous investigations were carried out by Professor Horsley on 
 his return, with the result that in their report to the Government 
 the committee unanimously expressed confidence in Pasteur's system 
 for the treatment of hydrophobia. 
 
174 PASTEUR. 
 
 and it was in connection with these inoculations that 
 we have handed down to us an incident which ex- 
 hibits at once the courag^e as well as the unselfish 
 devotion of this great man. At a time Avhen scepticism 
 was rife, and when attacks were raining down upon 
 him, a little child was brought to Pasteur which had 
 been bitten thirty-seven days previously by a rabid 
 animal. His assistants pointed out to him that to 
 treat a case, already practically hopeless by reason of 
 the long interval which had elapsed since the infliction 
 of the wound, would, in the almost certain event of 
 failure, endanger the reputation of the treatment and 
 expose him to fresh opposition from a public at that 
 time both unfavourable and unsymj^athetic. But 
 Pasteur, in spite of arguments which he could not but 
 admit were both legitimate and forcible, was not to be 
 deterred from making the attempt. " If the child has 
 but one in ten thousand chances of recovery I ought 
 to try everything," was his reply. The result was not 
 successful and the child died, and the attacks and 
 discussions were renewed with increased bitterness 
 and animosity. 
 
 The effect of this constant strain told terribly upon 
 Pasteur's health. Dr. Roux tells us how, " from time 
 to time, when the preventive inoculations were applied 
 to man, all repose was lost for him. Each bitten in- 
 dividual brought fresh pre- occupation to him. The 
 sight of the wounded children caused him especially 
 the most vivid emotion, which he could not control. 
 
 " When desperate cases were brought in for which 
 there was no remedy, Pasteur shared all the sufferings 
 of his patients. Every visit he made to them was 
 torture to him, and yet he could not help going to see 
 
RABIES. 175 
 
 them. It WMs necessary to take him away from Paris. 
 He was in Italy when those attacks were brought 
 against the antirabic inoculations which made so 
 iruich stir at the time but have been completely for- 
 gotten to-day. He was deeply distressed by them, 
 and from this time onwards Pasteur was obliged to 
 give up his life in the laboratory, and to a worker 
 such as he had been, Vinaction cdtait la tristesse." 
 
 All these researches on anthrax, the attenuation of 
 virus, swine measles, and rabies were accomplished by 
 Pasteur in less tban ten years, between 1876 and 
 18(S5. His assistants during that time were Joubert, 
 Chamberland, Thuillier, and Roux. To Roux we owe 
 the following vivid account of the life which was led 
 by the great master and his collaborateurs during this 
 period of concentrated scientific activity : — 
 
 " These years passed in the laboratory of the Rue 
 d'Ulm, remain ever present before me as the best of 
 my life. 
 
 " In order to be nearer our work, master as well as 
 disciples lived at the Ecole Normale. 
 
 "Pasteur was always first on the spot. Every morn- 
 ing at eight o'clock I heard his hurried and slightly 
 dragging footstep pass the window of the room which 
 I occupied at one extremity of the laboratory. Hardly 
 had he entered, than he went, paper and pencil in 
 hand, to the incubator to note down the condition of 
 the cultures, and then descended to the basement to 
 inspect the animals under experiment. After this we 
 made the autopsies, the culture-inoculations, and the 
 microscopic examinations. 
 
 " One ought to have seen Pasteur at his micro- 
 scope to obtain an idea of the patience with which he 
 
176 PASTEUR. 
 
 examined a preparation. But, in fact, he looked 
 at everything with the same minute care ; nothing 
 escaped his short-sighted eyes, and we used to say 
 jokingly that he saw the microbes growing in the 
 broth tubes. 
 
 "Afterwards Pasteur wrote down what had just 
 been observed. He permitted no one else to keep 
 these laboratory note-books, he himself recorded every 
 detail of the information which we gave him. 
 
 " What numbers of pages he thus covered with his 
 small, irregular, and cramped writing, with drawings 
 on the margin and back, the whole mixed up, difficult 
 to read to those without practice, but kept, all the 
 same, wdth extraordinary care! No fact was registered 
 which was not fully confirmed ; once written down, 
 the observations became incontestable truths to Pas- 
 teur. When, in the course of our discussions, the 
 words 'C'est sur le cahier' were heard, not one of 
 us dreamt of replying. 
 
 " The notes taken, we then discussed what experi- 
 ments should be made. Pasteur sat upright at his 
 desk, ready to write do^vn what should be decided 
 upon, Chamberland and I in front of him, leaning 
 against a glass cupboard. It was the important 
 moment of the day ; each one gave his opinion, and 
 often an idea, at first confused, became clear during 
 discussion, and ended by leading up to one of those 
 experiments which dissipated all doubts. Sometimes 
 we did not agree, and our voices became raised ; but 
 to Pasteur one could freely express one's thoughts. I 
 have never known him oppose a sound argument. 
 
 " A little before twelve, Pasteur was called to his 
 dejeuner ; at half-past twelve he came down to the 
 
RABIES. 177 
 
 laboratory, and oftenest on our return we found him 
 motionless, near a cage, observing with unwearying 
 attention a specially interesting guinea-pig or rabbit. 
 
 " Towards two o'clock, Madame Pasteur sent to 
 fetch him, for otherwise he would have forgotten 
 to go to the Academy and various committees of 
 which he was a member. 
 
 "We then employed the afternoon in carrying out 
 the experiments previously arranged, only interrupting 
 our work to permit of Chamberland's smoking a pipe, 
 for ' le Maitre ' had a horror of tobacco, and we only 
 smoked in his absence. 
 
 " Pasteur returned about five o'clock ; he at once 
 made himself acquainted with what had been done 
 and took notes. His notebook in his hand, he would 
 check the labels fastened on to the cages ; and then 
 he would tell us about any interesting communications 
 he had heard at the Academy, and chat about the 
 various papers. It was at such a time that Pasteur 
 opened out most willingly, especially if we roused him 
 with some objections. Then his eye, so clear, became 
 yet brighter ; his speech, a little slow to start with, 
 became more and more animated and fascinatinsf. He 
 developed the most profound and the most unexpected 
 ideas ; he proposed experiments of the most audacious 
 description. This rigorous experimenter possessed a 
 powerful imagination ; for him nothing was d priori 
 ridiculous. But his most enthusiastic outbursts 
 always led him to try some experiment, and in the 
 end he only retained that which was proven. 
 
 " His zeal was so infectious that, after listening to 
 him, the mind became croAvded Avith experimental 
 projects. 
 
 L 
 
178 PASTEUR. 
 
 "When we got him on to the subject of his early 
 researches, he would descant Uke a poet on molecular 
 dissymmetry and its relation to the dissymmetric 
 forces of nature. 
 
 " On such days as these Pasteur forgot all about 
 his dinner-hour. Madame Pasteur was obliged to 
 have him called two or three times, or came to 
 fetch him herself ; then he left us laughing, saying : 
 ' It is your fault that I shall be scolded.' 
 
 "The laboratory was tres fevnie; no one could 
 penetrate into it without first ringing at the entrance 
 door, which was always kept shut. Visitors hardly 
 ever got beyond the waiting-room. When M. 
 Pasteur was working, he was not in a humour to 
 receive even his friends ; an interruption made him 
 wretched. 
 
 " I see him turning round to the bore, waving his 
 hand as if to send him away, and saying, in a pleading 
 and despairing voice : ' No, not now ; I am too much 
 occupied.' He Avas, nevertheless, the simplest and 
 most accessible of men, but he could not understand 
 how anyone could disturb a savant when he was 
 writing down his laboratory notes. When Chamber- 
 land and I were busy over some interesting experi- 
 ment, he mounted guard round us, looked through 
 the glass door when our comrades came to call upon 
 us, and went himself to receive them and to politely 
 show them out. 
 
 " These freaks of Pasteur's showed so naively his 
 entire preoccupation with his work that no one ever 
 felt hurt by them. 
 
 "Pasteur was al ways plotting out experiments, and 
 he lotted down his ideas on the leaves of a little note- 
 
IIABIES. 179 
 
 book, or on pieces of cardboard, which he carefully 
 preserved. 
 
 " His left hand having remained awkward since the 
 attack of paralysis which he had in 1868, he entrusted 
 the carrying out of his experiments to his assistants ; 
 an irreproachable experimenter himself, he was very 
 exacting in what he demanded of others. For him 
 no experiment was impossible. When we remarked 
 that what he expected of us presented particular 
 difficulties, he would reply, ' That is your affair ; 
 arrange it as you like, provided it is done, and 
 well done, too.' And he always ascertained for 
 himself whether it was well done, separating out 
 what was strong and what was weak with admirable 
 sagacity. 
 
 " A communication of Pasteur's to the Academy of 
 Sciences or to the Academy of Medicine was an event; 
 for he never published anything which was not 
 finished. Each one of his memoirs only occupies a 
 few pages of the Gomptes rendus, but it contained the 
 results of hundreds of experiments. One can read 
 and re-read them, one always finds something fresh 
 to learn; often a simple phrase opens up a new path, 
 and many such which have been thus indicated 
 have not yet been traversed. Pasteur's whole indi- 
 viduality comes out in his writings ; his imagination is 
 revealed in them by the depth and audacity of his 
 generalisations, the vigour of his mind by the cor- 
 rectness of his views and the strength of his con- 
 clusions, his enthusiasm by the emotion of his 
 language. 
 
 "Before writing, Pasteur read and re-read his 
 experimental notebooks, then he dictated to one of 
 L 2 
 
180 PASTEUR. 
 
 US, or more frequently to Madame Pasteur. He kept 
 the manuscript sometimes for weeks, constantly re- 
 touching it ; when he was satisfied, he communi- 
 cated it to us and discussed the mode of expres- 
 sion with us ; often he received observations with 
 impatience, but he always valued them if they were 
 correct. 
 
 "Madame Pasteur recopied it in her beautiful hand- 
 writing, so easy to read ; Pasteur never would send 
 a manuscript scored with erasures to the printers ; if 
 he altered some passage he stuck some gummed 
 paper, cut to the right size, over the lines and wrote 
 it afresh. During all this work of editing, the subject 
 treated of developed wonderfully, and we, the assis- 
 tants of the Master, who knew how far the experi- 
 ments had carried it, were astounded to see how it 
 had grown and become transformed in the final 
 memoir." 
 
 Before closing this chapter on rabies, it is of 
 interest to glance at the report which M. Henri 
 Pottevin has just published of the antirabic inocula- 
 tions which have been carried out in Paris during 
 the past ten years (1886-1896), the greater number of 
 which have been performed in that now world-famous 
 building the Institut Pasteur, the foundation of which 
 afforded such immense gratification to its great name- 
 sake, and was the public expression of gratitude for 
 the countless benefits its first great director had 
 bestowed upon his country. 
 
 The following table shows the number of persons 
 treated and the mortality in the various years : — 
 
RABIES. 
 
 181 
 
 Years. 
 
 Persons treated. 
 
 Deaths. 
 
 Mortality per cent. 
 
 1886 
 
 2,671 
 
 25 
 
 0-94 
 
 1887 
 
 1,770 
 
 14 
 
 0-79 
 
 1888 
 
 1,622 
 
 9 
 
 55 
 
 1889 
 
 1,830 
 
 7 
 
 0-38 
 
 1890 
 
 1,540 
 
 5 
 
 0-32 
 
 1891 
 
 1,559 
 
 4 
 
 0-25 
 
 1892 
 
 1,790 
 
 4 
 
 0-22 
 
 1893 
 
 1,648 
 
 6 
 
 0-36 
 
 1894 
 
 1,387 
 
 7 
 
 0-50 
 
 1895 
 
 1,520 
 
 5 
 
 0-33 
 
 1896 
 
 1,308 
 
 4 
 
 0-30 
 
 It will be observed that there were fewer cases 
 treated at the Institut Pasteur in 1896 than in any 
 previous year. . This is attributable to the fact that 
 similar institutes, where anti-rabic inoculations are 
 carried out, have been started in increasing numbers 
 not only in France but all over the world ; hence 
 districts and countries which used to send a consider- 
 able contingent of cases each year to the Paris centre 
 are now in a position to carry out the inoculations on 
 the spot. 
 
 The following table shows the nationality of the 
 18,645 persons treated at the Institut Pasteur during 
 the past decade : — 
 
 Germany- 
 England 
 Austria 
 Belgium 
 Brazil ... 
 Egypt ... 
 Spain . . . 
 United States 
 Greece ... 
 Holland 
 Italy ... 
 
 44 
 870 
 
 94 
 429 
 
 13 
 
 45 
 353 
 
 33 
 175 
 
 87 
 159 
 
 India . . . 
 
 Morocco 
 
 Portugal 
 
 .. 95 
 
 2 
 
 .. 333 
 
 Roumania 
 
 Russia ... 
 
 .. 53 
 .. 194 
 
 Servia ... 
 Switzerland 
 Turkey . . . 
 Bulgaria 
 Monaco... 
 
 1 
 
 .. 82 
 
 ... 31 
 
 1 
 
 2 
 
182 PASTEUR. 
 
 Thus 3,096 were foreigners, and 15,549 French- 
 men. 
 
 These figures show that of the foreigners treated 
 at the Institut Pasteur by far the largest contingent 
 came from England, a circumstance which can be 
 regarded only as a national disgrace. Amongst the 
 civihsed countries of the world, we are indeed almost 
 unique in obstinately neglecting to provide this 
 benefit of modern science for those of our unfortunate 
 countrymen who stand in need of it. This omission 
 means, of course, that whilst the well-to-do who have 
 the misfortune to be bitten by a rabid dog can and do 
 largely avail themselves of the hospitality and scien- 
 tific skill which is to be obtained at the Institute on 
 the banks of the Seine, the poor, when falling victims 
 to the same misfortune, have to forego the consolation 
 which is afforded by the costly trip to the French 
 capital. It is to be hoped that the British electorate, 
 composed, as it now is, mainly of those who would 
 thus be deprived of the benefits of modern science, 
 will before long insist upon the reform of that legisla- 
 tion which owes its existence to the noisy and mis- 
 directed energy of a group of influential persons who, 
 actuated, as the case may be, either by a misguided 
 sentimentalism based on ignorance or by a wicked 
 and selfish hypocrisy, are most dangerous enemies of 
 the human race and of that scientific progress upon 
 which the continued welfare of the latter depends. 
 
 Thus it is that the British Institute of Preventive 
 Medicine, established in London in 1891 with infinite 
 difficulty, and mainly through the strenuous efforts of 
 Lord Lister, Sir Henry Roscoe, and other leaders of 
 science in Great Britain, has made but little progress 
 
RABIES. 183 
 
 comparerl with the magnificent sister institutions 
 which have been founded in the other great European 
 capitals. 
 
 We must, in fact, recognise that in the matter of 
 bacterio-pathology the British Empire counts now for 
 Httle more than a cipher, and has to summon outside 
 aid in almost every emergency — Koch, of Berlin, 
 exposes the bacterial nature of cholera in India ; 
 Haff'kine, of the Pasteur Institute, devises a method 
 of contending against it by protective inoculation ; it 
 is Koch, again, who is called upon to combat the 
 rinderpest in South Africa ; it is Yersin, of the 
 Pasteur Institute, who discovers the plague bacillus 
 at Hong Kong, and it was to him and to the Institute 
 that has produced him that we appealed for assistance 
 during our recent embarrassment in Bombay. How 
 long is " the greatest empire the world has ever seen," 
 to use the phrase which statesmen in the Jubilee 
 year of 1897 kept dinning into our ears, to occupy 
 this degrading position of dependence ? In this 
 matter, indeed, we can learn from almost every other 
 country in the civilised world, for hardly anywhere is 
 this department of science at such a discount as in 
 this globe-girdling empire of which we are so proud. 
 To give the most recent instance that comes to hand 
 of the value set upon researches in this branch of 
 science by other countries, we hear of a Bill having 
 just been introduced into the Legislature of Brazil 
 offering a prize of £44,000, to be divided into two 
 equal parts, which are to be awarded to the author of 
 a work demonstrating the existence of a bacillus of 
 yellow fever and the method of recognising it, and to 
 the discoverer of an efficacious means of treating the 
 
184 PASTEUR. 
 
 disease. The Medical Institute of Rio Janeiro, the 
 Hygienic Institute of Berlin, and the Pasteur Institute 
 of Paris are to decide as to the award of the prizes. 
 Where, we should like to ask, is a British Institute to 
 be found capable of adjudicating on such claims ? 
 The Bill further provides for the reservation of a sum 
 of £22,000, to be applied to the creation of an establish- 
 ment for the preparation of a curative serum, the 
 discoverer of which will be apjDointed organising 
 director of the Institute. The former of these prizes 
 will probably be awarded to Dr. Sanarelli, who has 
 already discovered a bacillus supposed by him to be 
 the cause of yellow fever, and the claims of which are 
 at present being investigated by the authorities of the 
 Institut Pasteur. In the meantime, the Legislature 
 of Uruguay has conferred honorary citizenship on 
 Dr. Sanarelli in recognition of his discovery, and has 
 voted him a Q^rant of £2,000. 
 
CHAPTER XY. 
 
 THE INSTITUT PASTEUR. 
 
 In an unfrequented part of Paris, far removed from 
 the busy haunts of its citizens, there existed for 
 upwards of a century and a half a large market 
 garden. The few pedestrians Avho by chance found 
 their way to this remote district were rewarded by 
 the opportunity of feasting their eyes on no less 
 than eleven thousand square metres of vegetables ! 
 
 Towards the end of May, in the year 1887, how- 
 ever, the whole prospect was changed. Hundreds of 
 labourers were at work upon this " hectare de salades." 
 " Hastily they dug to great depths, to establish the 
 foundations of a monument which it was desired should 
 be indestructible " ; for here was the site upon which the 
 Institut Pasteur was to rise up — that splendid national 
 tribute to a man of genius whose name was now a 
 household word in all parts of the land, in all classes 
 of society. 
 
 The extraordinary enthusiasm which accompanied 
 the foundation of this great Institution has certainly 
 not been equaUed in our time. Considerable sums of 
 money were subscribed in foreign countries, whilst 
 contributions poured in from every part of France.^ 
 Even the inhabitants of obscure little towns and 
 
 * The total sum subscribed and announced by the treasurer of the 
 fund at the opening ceremony amounted to 2,586,680 francs. 
 
186 PASTEUR. 
 
 villages organised fetes, and clubbed together to send 
 their small " cadeau de la misere " ; and we read of the 
 workpeople employed in a glass factory approaching 
 M. rran9ois Coppe, the poet, and begging from him 
 some verses, so that their gift might be accompanied 
 by a suitable tribute to the genius of Pasteur. 
 
 Collective subscriptions were started, amongst which 
 that offered by the Trocadero will be specially remem- 
 bered as having received from Pasteur the following 
 felicitous acknowledgment : — " Les grands charmeurs 
 de I'humanite heureuse apporterent leur glorieux 
 concours a ceux qui veulent servir I'humanite 
 souffrante." 
 
 But perhaps the contribution by which Pasteur, with 
 his intense patriotism, was most deeply moved was 
 that forwarded from Alsace-Lorraine. It was, as we 
 have seen, from Alsace also that Pasteur received his 
 first patient ; and the young Alsatian has ever since 
 remained one of his most devoted and grateful ad- 
 herents. Enthusiasm was, however, not confined to 
 offerings of money ; valuable services were ungrudg- 
 ingly given by those entrusted with the designing and 
 carrying out of the plans for the building up of this 
 remarkable edifice. 
 
 " La voila done batie, cette grande maison dont on 
 pourrait dire qu^il n'y a pas une pierre qui ne soit le 
 signe materiel d'une genereuse pensee. Toutes les 
 vertus se sont cotisees pour elever cette demeure du 
 travail." 
 
 It was on the 14th November, 1888, that the 
 President of the Republic, supported by the great 
 officers of State, representatives of various foreign 
 Governments, and a brilliant gathering of distinguished 
 
THE INSTITUT PASTEUR. 187 
 
 members of both the artistic and scientific worlds, 
 formally opened the Institut Pasteur. Amongst the 
 great crowd present on that day were past and 
 present pupils of Pasteur's, and deputations from all 
 the students in Paris. 
 
 The proceedings commenced with a discourse by 
 M. Bertrand, the Perpetual Secretary of the Academy 
 of Sciences, and Member of the French Academy. 
 
 " During forty years, my dear Pasteur, you have let 
 glory come to you without ever pursuing it. Amongst 
 all the paths where often one seeks for it, there was 
 but one known to you — that of truth. . . . The 
 date of the 14th November, 1888, will remain immortal 
 in the history of medicine. ... I cannot yield 
 to the temptation of reviewing the long series of your 
 researches, admired by such great judges as Claude 
 Bernard, Balard, Dumas. On every road of science 
 we meet you. . . . It is to thank you in the name 
 of science, to rejoice in the name of humanity, and to 
 triumph in the name of France, that we are all met 
 here to-day." 
 
 In an able speech, Dr. Grancher next addressed 
 the assembly, reviewing the history of the difficulties, 
 the trials, and the triumphs which had accompanied 
 the discovery and practice of the new treatment for 
 rabies. 
 
 " You must know, gentlemen," he remarked in 
 conclusion, " that the Institut Pasteur has been not 
 alone founded for the treatment of rabies, but also for 
 the scientific study of means practically to compass 
 diseases which decimate the human race — diphtheria, 
 typhoid fever, phthisis, etc. The large laboratories 
 which are to be opened to French and foreign doctors 
 
188 PASTEUR. 
 
 will thus become a source of benefit to the whole of 
 humanity, as well as a powerful means of diffusing 
 and spreading abroad French science." 
 
 The treasurer of the fund, M. Christophle, next 
 rose, and, in a graceful and picturesque speech, re- 
 ferred to the financial and other support which the 
 Institute had already received. 
 
 " Certainly it is for you, Sir " (addressing Pasteur), 
 " a happiness rare and hardly hoped for, which may 
 console you for the passionate struggles, the keen 
 emotions, and the crises, sometimes so terrible, 
 through Avhich 3^ou have passed. When I think of 
 this past, so full of trouble and of danger, in spite 
 of myself I recall also the irony of those ready made 
 phrases which speak of the serenity of science and 
 the peace of laboratories." 
 
 Pasteur's emotion was too great to permit him to 
 deliver the address he had prepared, and his son, 
 therefore, read his discourse, from which the following 
 extracts have been taken : — 
 
 " Never has a Frenchman addressing himself to 
 other Frenchmen been more profoundly moved than 
 am I at this moment. . . . But, alas ! I have the 
 poignant melancholy of entering this house of work 
 as a man ' vaincu du temps,' who has no longer 
 around him any of his masters, nor even any of his 
 comrades in past contests — neither Dumas, Bouley, 
 Paul Bert, nor Vulpian — who, even like you, my dear 
 Grancher, was my adviser in early days, and became 
 the most convinced adherent and the most active 
 defender of my method ! . . . Our Institute shall 
 become at once a dispensary for the treatment of 
 rabies, a centre of researches for the study of infectious 
 
THE INSTITUT PASTEUR. 189 
 
 diseases, and a centre for the teaching of subjects re- 
 lating to microbiology. Born but yesterday, but born 
 completely armed, this science draws such strength 
 from its recent victories that it entices all intellects. 
 
 " This enthusiasm, which has been kindled in you 
 when young, keep it, my dear colleagues, but give to 
 it, as an inseparable companion, unflinching self- 
 control. Advance no theories — nothing which cannot 
 be proved in a manner at once simple and conclusive. 
 Cultivate the spirit of criticism. By itself it is neither 
 a generator of ideas nor a stimulus to great things. 
 Without it nothing can avail. With it will always 
 remain the last word. 
 
 " This that I ask of you is what you again, in your 
 turn, will demand of the disciples who gather round 
 you ; and for the investigator it is the hardest ordeal 
 which he can be asked to face — to believe that he has 
 discovered a great scientific truth, to be possessed with 
 a feverish desire to make it known, and yet to impose 
 silence on himself for days, for weeks, sometimes for 
 years, whilst striving to destroy those very conclusions, 
 and only permitting himself to proclaim his dis- 
 covery when all the adverse hypotheses have been 
 exhausted. Yes, that is a difficult task. 
 
 " But when, after many trials, you have at length 
 succeeded in dissipating every doubt, the human 
 soul experiences one of the greatest joys of which it 
 is capable. . . . 
 
 " If it be permitted to me, Monsieur le President, 
 to conclude with a philosophical reflection, suggested 
 by your presence in this hall of labour, I would 
 point out that two contrary laws appear here to-day 
 to be in conflict — a law of blood and death, which. 
 
190 PASTEUR. 
 
 conceiving each day some new mode of warfare, 
 compels the people to be ever ready for the field of 
 battle ; and a law of peace, of labour, and of health, 
 which cherishes no other dream than the delivery 
 of man from the plagues which besiege him. 
 
 " The one seeks only violent conquests, the other 
 nothing but the alleviation of humanity. The latter 
 law places a human life above all victories ; the former 
 sacrifices hundreds of thousands of lives to the ambi- 
 tion of a single life. The law of which we are the 
 instruments seeks, even amidst carnage, to cure the 
 bleeding wounds wrought by this law of war. The 
 dressings suggested by our antiseptic methods may 
 preserve the lives of thousands of soldiers. 
 
 " Which of these laws will finally prevail ? God 
 alone knows. But what we may be assured of is that 
 French science will strive, in obeying this law of 
 humanity, to extend the frontiers of life." 
 
 At the close of this fine oration enormous enthu- 
 siasm prevailed, and the President of the Rep)ublic, 
 rising, said : " M. Pasteur desires no other recompense 
 but that which we can bestow on his coUaborateurs. 
 M. Grancher and M. Duclaux are herewith created 
 Otficers and M. Ghantemesse Ghevalier of the Legion 
 of Honour." 
 
 And so closed a ceremony perhaps unique in the 
 annals of science. That the Institute inaugurated 
 under such auspicious circumstances has withstood 
 the attacks and machinations of its opponents and 
 enemies, and has so far fulfilled the high promise 
 with which it entered upon its career no one at the 
 present day questions ; that it will continue to uphold 
 and perish the lofty standard set by its great name- 
 
THE INSTITUT PASTEUR. 191 
 
 sake is sufficiently guaranteed by the active presence 
 within its walls of men such as Duclaux, Roux, 
 Metchnikoff, and other disciples and workers be- 
 queathed to it by its first organiser and director. 
 
 M. Duclaux, upon whom, since 1895, has fallen 
 the responsibility of directing the Institute, was, we 
 have seen, for years intimately associated with Pasteur 
 and his work. He it was who first conceived the idea 
 of bringing out the Annales de Vlnstitid Pasteur, a 
 journal which, under his able editorship, is second to 
 none amongst all the new bacteriological publications 
 of recent years. In 1888 he was appointed Professor 
 at the Sorbonne, but, by special arrangement, his 
 work is conducted entirely at the Institute. 
 
 It is with the chemical aspects of bacteriology that 
 M. Duclaux is chiefly concerned and has done his best 
 work, and it is stated that he hopes to still further 
 extend the usefulness of the Institute by establishing 
 a school for the study of industrial fermentations, and 
 that he is anxious to work out scientifically the prin- 
 ciples which underlie the manufacture of wines, beer, 
 dairy produce, etc. 
 
 In carrying out this scheme M. Duclaux will be 
 taking up again the threads of those classical re- 
 searches which Pasteur was constrained to abandon 
 for the study of diseases, and in the ardent pursuit of 
 which he was reluctantly compelled to let his earlier 
 work remain uncompleted. 
 
 The Pasteur Institute has been so inseparably 
 associated, in the public mind, with the prevention of 
 disease that this new departure, which its present 
 Director is anxious to inaugurate, may come as a sur- 
 prise to many ; but that the original conception of 
 
192 PASTEUR. 
 
 the Institute as a centre for the study and preven- 
 tion of disease will not suffer is assured by the fact 
 that Dr. Roux will continue to preside over the de- 
 partment in which he has achieved such signal 
 success in the new treatment of diphtheria,"^ and that 
 Dr. Grancher remains at the head of the anti-rabic 
 department. 
 
 The personality of Dr. Roux, now Sub-Director of 
 the Institute, with whom and the other Professors 
 gathered round M. Duclaux the fortunes of the 
 Pasteur Institute now rest, has been recently so 
 vividly portrayed by M. de Fleury that it is impossible 
 to resist conveying to the reader some impression of 
 so remarkable an individuality. Originally a student 
 at Clermont-Ferrand under M. Duclaux, who did not 
 fail to notice a pupil " si taciturne et si studieux," 
 Roux followed his teacher to Paris, where the latter 
 procured for him a minor appointment at the Hotel 
 Dieu. Here Roux exhibited that independence of 
 character, that almost imperious demand for liberty 
 
 * In this connection it is of interest to note the report of the 
 medical superintendents to the Metropolitan Asylums Board, London, 
 on the use of antitoxin in the treatment of diphtheria during the year 
 1896. It confirms and extends the favourable conclusions reached ip 
 the previous year, when antitoxin was first used. The statistical re- 
 sults with regard to mortality are compared with those for 1894, the 
 year immediately preceding the introduction of antitoxin and the one 
 in which the lowest mortality had been recorded up to that time ; they 
 show a marked improvement in all classes of cases, and especially 
 in the severer ones. The more important facts may be tabulated 
 thus: — 
 
 PERCENTAGE OF MORTALITY TO CASES. 
 
 
 All Cases. 
 
 Under 5 Years. 
 
 Laryngeal 
 Cases. 
 
 Tracheotomy 
 Cases. 
 
 1894 
 
 ... 29-6 
 
 47-4 
 
 620 
 
 70-4 
 
 1896 
 
 ... 20-8 
 
 30-2 
 
 29-6 
 
 41©' 
 
THE INSTITUT PASTEUR. 193 
 
 of judgment, which never forsook him even in the 
 presence of ?iis deeply venerated and much-loved 
 master, Pasteur, when he chanced not to be in com- 
 plete accord with him on some matter of detail. 
 His insight, unbounded patience, and his most 
 scrupulous scientific conscientiousness soon obtained 
 for him the respect of all with whom he came in con- 
 tact on entering Pasteur's laboratory. Since then his 
 splendid investigations at the Institute have placed 
 him in the first rank of scientific men. 
 
 For several years Roux has lectured at the Insti- 
 tute, and so eager is the competition to attend his 
 courses of lectures that it is necessary to apply for a 
 place eighteen months in advance, a circumstance 
 which will hardly surprise those who had the good 
 fortune to listen to the truly marvellous discourses, in 
 his own beautiful language, which on two occasions 
 he has delivered in this country. His audience is 
 gathered from all parts, and it may truly be said that 
 he it is who has initiated French scientists all over 
 the country, and not a few foreigners, into the mysteries 
 of bacteriological technique, and has incited them to 
 the study of microbes and toxins. 
 
 " I do not think it is possible," writes M. Fleury, 
 " to find a more eager worker. He takes no rest 
 either on Sundays or fete days, and nothing has ever 
 dissuaded him from the one set purpose which 
 dominates him — to do good scientific work and make 
 useful discoveries, not for his own reputation but for 
 the glory of the Institut Pasteur, of that beloved 
 maison-r)%ere to which the Pasteurians belong." 
 
 In the department devoted to morphologica 
 bacteriology, \)y. Metchnikoff continues to act as 
 
 M 
 
194 PASTEUE. 
 
 Director. Originally a student at Berlin under 
 Virchow, this brilliant and accomplished Russian 
 investigator has pursued his researches on the 
 morphology of the lowest animalculae in all parts 
 of the world — in Italy, in Madeira, in Odessa. It 
 was whilst Professor at Odessa that he wrote to 
 Pasteur and asked for a place in his laboratory, and 
 since that time he, with his gifted wife, has worked 
 without intermission at the Institute. Here it is that 
 he has experimentally elaborated his celebrated 
 theories of phagocytosis, which assign such important 
 functions to the migratory cells of the body in the 
 conflict of the system with disease. 
 
 This remarkable theory, which was the subject of 
 so much discussion a few years ago, is the outcome of 
 extended researches on the behaviour of the colour- 
 less corpuscles in the most varied forms of the animal 
 kingdom. 
 
 An admirable outline of these laborious studies, 
 and the conclusions drawn from the observations by 
 their author, is given in M. MetchnikofPs work en- 
 titled " Lemons sur la Pathologic Comparee de I'ln- 
 flammation." 
 
 The Pasteurians have a profound respect and 
 admiration for this distinguished investigator, and 
 themselves agree that " apres M. Pasteur, c'est 
 Metchnikoff notre homme de genie." 
 
 Practical bacteriology is another department of 
 the Institute's programme, and deals Avith the applica- 
 tions of bacteriology to questions ot hygiene, under 
 which head the preparation of the vaccines of swine 
 fever and anthrax is included. Over this work M. 
 Chamberland presides, whose name is so well known 
 
THE INSTITUT PASTEUR. 195 
 
 even to the lay public in connection with the Pasteur- 
 Chamberland filter, and which, besides its general 
 application, has also been of priceless value as a 
 scientific instrument in the bacteriological laboratory 
 for separating bacteria from their chenriical products. 
 Some idea of the labour which the elaboration of these 
 vaccines entails may be gathered from the fact that 
 in France alone it is stated that 900,000 sheep and 
 from 400,000 to 500,000 oxen are annually inoculated 
 with anthrax vaccine. 
 
 Separate departments also exist for comparative 
 bacteriology, in which the study of bacterial diseases 
 is pursued ; and technical bacteriology, in which, as 
 we have seen. Dr. Roux superintends the instruction 
 of students in the technique of the subject. 
 
 But a very inadequate idea would be obtained of 
 the splendid work which the Pasteur Institute has 
 accomplished without a reference to the brilliant 
 students and disciples which it has already raised and 
 dispatched to all quarters of the globe to carry on the 
 traditions and uphold the honour of the 'inaison-mere* 
 
 * Amongst the numerous institutions of this kind now existing, 
 the erection of a Pasteur Institute at Athens deserves mention. The 
 credit of founding this institution was due to Dr. Pampoukis, who 
 studied for a time under Pasteur in Paris. On his return to Athens 
 he started a microbiological institute on his own account, and eventu- 
 ally established the Pasteur Institute at his own exjjeuse. In due 
 time the municipality and the Government granted him a small yearly 
 allowance. The Consul, in his report, observes that it is practically 
 impossible to overestimate the value of " such nn establishment in 
 the Levant, which is overrun with ownerless dogs. A muzzling 
 order does exist in Attica, but it is not enforced, and the distribution 
 of poisoned meat in the streets of Athens and the Pirseus is apparently 
 the only attempt made by the authorities to deal with an increasing 
 amount of rabies. The lack of water and the prevailing disregard of 
 all forms of animal suffering largely contribute to this result." 
 M 2 
 
196 PASTEUR. 
 
 Amongst such we may mention Calmette, lately 
 Director of a Pasteur Institute in Cochin China, 
 Nicolle, who occupies a similar position at Stamboul, 
 and Yersin in Annam. 
 
 Foremost among these must be placed Dr. Cal- 
 mette, who, originally a student under Dr. Roux, left 
 for Cochin China to undertake the establishment of 
 a Pasteur Institute at Saigon, the first to be founded 
 in the French colonies. Here he struck out a com- 
 letely new line of investigation, and one which again 
 indicates the extraordinary fertility of the ideas which 
 are gathered from the study of micro-organisms. If, 
 as had been shown in the case of tetanus and diph- 
 theria, the serum of an animal rendered insusceptible 
 to a particular disease can counteract the poisons 
 manufactured by the specific bacteria of that disease, 
 may it not also be possible to counteract in the same 
 way poisons that have a non-bacterial origin altogether ? 
 This question was answered by the remarkable re- 
 searches of Calmette on the nature of serpents' 
 venom and the artificial production of immunity 
 from the poisonous effects of snake-bite, researches 
 which, admirable alike in their conception, execution, 
 and in the results achieved, have justly made his 
 name famous throughout both the scientific and 
 medical worlds. 
 
 By gradually accustoming animals (horses by 
 preference), to larger and larger doses of snake 
 poison, he has succeeded in rendering the blood 
 serum of such animals an antidote to the most potent 
 serpent venom, such serum possessing the power, on 
 being injected into other animals, of protecting the 
 latter from the otherwise lethal effects of this poison. 
 
THE INSTITUT PASTEUR. 197 
 
 Since Dr. Calmette has returned to his native country 
 in the capacity of Director of the Pasteur Institute 
 at Lille, he has logically pursued his ideas by extending 
 this method to the artificial production of immunity 
 towards ahrine, a highly toxic vegetable poison, as 
 well as continuing his researches on serpent venoms 
 of various origin. Such successful results have 
 already folloAved in Australia the use of Calmette's 
 serums and methods in the treatment of snake-bites, 
 that an official dispatch was forwarded from this 
 colony to the French Minister of Foreign Affairs, 
 through the English Ambassador in Paris, congratu- 
 latinof the Government on Calmette's discoveries, and 
 expressing the gratitude of. the colony for the services 
 which he had rendered. 
 
 Yet another brilliant disciple of Pasteur's is Yersin, 
 whose name will always be associated with that of 
 Dr. Roux in the classical researches they together 
 published on the toxins elaborated by the diphtheria 
 bacillus ; whilst his investigations on the plague 
 bacillus have brought him still more prominently 
 before the Avorld. 
 
 When a youth of but twenty, Yersin had the rare 
 good fortune to obtain an entrance to the Institut 
 Pasteur. The extraordinary ardour with which he 
 devoted himself to his work rapidly won for him the 
 admiration and respect of all his colleagues. Desiring 
 to travel, he obtained a medical appointment in the 
 colonies, and it w^as whilst at Tonkin in the, spring of 
 1894 that he received the request from the French 
 Government to proceed to Hong Kong to study the 
 plague which had recently broken out there. The 
 report which he subsequently published is so 
 
198 PASTEUR. 
 
 interesting that it is tempting to describe in some 
 detail the work which Yersin accompHshed during 
 his mission to Hong Kong. 
 
 Yersin arrived in the city a few weeks after the 
 plague had commenced its terrible career there, a 
 career which had already claimed the lives of 300 
 Chinese, and was yet to exact a tribute of over 
 100,000. Obtaining permission from the authorities, 
 he erected a small hut within the precincts of 
 the principal hospital ; and here, in a concentrated 
 plague atmosphere, he took up his quarters, and 
 hastily improvising a laboratory, commenced his in- 
 vestigations. 
 
 So far the plague had confined itself to the 
 insanitary Chinese quarters of the city, and Yersin 
 mentions that the wretched cabins occupied by the 
 natives were often not only without windows of any 
 kind, but were sunk below the level of the ground, 
 which, combined with the shocking overcrowding 
 which prevailed, converted such dens into plague- 
 incubators of the most fulsome and dangerous 
 character. In these infected districts, one of the 
 first thinofs which attracted Yersin's attention was 
 the extraordinary number of dead rats which lay 
 about in all directions in the houses as well as in the 
 streets ; but, on inquiry, he soon learnt that this rat 
 mortality was a well-known forerunner of the plague, 
 that the latter usually attacks animals such as rats 
 and mice, and in the country districts also swine and 
 buffaloes, before it touches human beings. 
 
 An examination of these dead rats showed that 
 the appearances differed in no way from those which 
 characterise the plague in man; and the extreme 
 
THE INSTITUT PASTEUR. 199 
 
 susceptibility of these animals furnished Yersin at 
 once with a valuable means of tracking out the virus. 
 His first step was to make careful examinations of 
 the bubonic material present in the tumours which 
 accompany the disease, and here he discovered 
 immense numbers of a short bacillus which appeared 
 to be almost exclusively in possession of the field. 
 These, he found, were readily stained, and could be 
 grown with ease in the usual bacterial culture-media. 
 Further investigation showed that these same bacilli 
 were invariably present in the ganglia and liver and 
 spleen of plague patients ; that they were, however, 
 rarely to be found in the blood, and then but in small 
 numbers, and usually only in rapidly fatal cases a 
 short time before death. 
 
 Healthy rats and mice inoculated with pure 
 cultures of this bacillus succumbed, exhibitinof the 
 typical plague symptoms, and thus the first step was 
 accomplished — the identification of the specific virus 
 of plague. 
 
 Yersin was at first of opinion that rats were the 
 principal disseminators of the disease, for healthy mice 
 shut up with plague-stricken rats rapidly developed the 
 disease and succumbed; but he noticed later the 
 curious fact that, in the little room where he carried 
 out his post-r}iortem examinations, immense numbers 
 of dead flies were scattered about in all directions. 
 He therefore determined to ascertain if this wholesale 
 slaughter of flies had any connection with plague 
 infection. 
 
 Taking some of these insects, and first removing 
 the head, wings, and feet, he pounded up their bodies 
 in broth. On subsequent examination the liquid thus 
 
200 PASTEUR. 
 
 obtained exhibited masses of bacilli closely resembling 
 the now familiar plague microbe. To place their 
 identity beyond doubt he inoculated some of this broth 
 into mice, with the result that the latter died of plague. 
 That flies may materially assist in the dissemination 
 of the disease was thus established. With the slender 
 accommodation and primitive means at his disposal, 
 it was impossible for Yersin to further pursue his 
 investigations in preparing a plague anti-toxin on the 
 spot, and he therefore forwarded cultures of his 
 bacillus to the Institut Pasteur, and from here in the 
 course of the following year, under the joint names of 
 Yersin, Calmette, and Borrel, was published the memoir 
 describing the production of an anti-plague serum. 
 
 This new anti-toxin has been successfully employed 
 by Yersin, now Director of a Pasteur Institute at Nha 
 Trang,in Annam,in undoubted cases of plague at Amoy. 
 
 Pasteur has sometimes been reproached for not 
 having opened his laboratory more freely to students, 
 and he has been accused of desiring to keep his 
 methods of research too much to himself and his 
 assistants. " Nothing," remarks Dr. Roux, " is more 
 unjust. In his scientific memoirs Pasteur disseminated 
 new ideas with a liberal hand, and it was open to 
 everyone to make use of them. He was indeed an 
 incomparable master ; he never brought forward any 
 fact without supplying the means for its control ; but 
 instead of losing himself* in useless detail, and in de- 
 scribing the arrangement of apparatus which everyone 
 could easily imagine for himself, he confined himself 
 to mentioning those conditions which were both 
 necessary and sufficient. 
 
 " The laboratory in the Rue d'Ulm was not suitable 
 
THE INSTrrUT PASTEUR. 201 
 
 for the accorrirnodation of a large niiiubcr of investi- 
 gators ; there was only rooiri enough for Pasteur and 
 his assistants. Moreover, Pasteur only worked at his 
 ease in silence and irieditation ; in his vicinity he only 
 tolerated his assistants ; the presence of a stranger 
 whilst he was occupied ?^ufficed to disturb his work. 
 One day on going to visit Wurtz at the Ecole de 
 Medecine, we found the great chemist surrounded by 
 his students, the laboratory resembling a hive full of 
 bees in its bustling activity. ' How,' exclaimed Pasteur, 
 ' can you work in the midst of such a commotion ? ' — 
 * It stimulates my ideas,' replied Wurtz — 'It would 
 effectually banish all mine,' was Pasteur's answer." 
 
 Pasteur himself has expressed his opinion " that if 
 primary and secondary education are to be made to 
 flow as great rivers, it is necessary to be concerned 
 about the source — that is to say, about higher 
 education. Such instruction must always be reserved 
 for a small number, but it is upon this small number 
 and upon its elect that the prosperity, the glory, and 
 the ultimate supremacy of a people depend." 
 
 There is no country which stands in more need of 
 the admonition conveyed in the last sentence than our 
 own. Indeed, it would appear that even the meaning 
 of the words " higher education " is not understood by 
 our legislators ; thus whilst primary and secondary 
 education have during the present generation been 
 enormously extended, practically no provision has 
 been made for that higher education upon which all 
 real progress depends. In this matter, indeed, the 
 words of John Stuart Mill apply with remarkable force. 
 
 " The general tendency of things throughout the 
 world is to render mediocrity the ascendant power 
 among mankind." 
 
202 PASTEUR. 
 
 Such research as is carried on in our midst 
 is almost invariably performed either by enthusiasts 
 with private means or by persons holding appoint- 
 ments, in addition to or in spite of the arduous 
 duties which these appointments entail. In the case 
 even of the highest academic posts which we possess, 
 it is comparatively elementary teaching which is the 
 main duty, and capacity for which is the quality in 
 the occupant which is most highly prized by the 
 governing authorities. Whether the occupant of 
 such a post carries on research or not is entirely a 
 matter of personal inclination, and would appear to 
 be viewed with hardly more concern by the educa- 
 tional authorities than whether he pla^^s golf or rides 
 a bicycle. Under such conditions it is surely not 
 surprising that so little research is carried out in this 
 country, but rather that any is carried on at all, and 
 that some is of the very highest quality. 
 
 Shortly after the opening of the Pasteur Institute 
 the feeling amongst scientific men in this country 
 became more and more strongly emphasised that we, 
 as a nation, could not, with self-respect, continue to 
 accept the gratuitous services of its staff for the relief 
 of the numerous English people who, bitten by rabid 
 animals, sought relief at the hands of Pasteur and his 
 assistants in Paris. Considerably over two hundred 
 such cases had already been treated at the Institute ; 
 and it will be seen from the following letter, addressed 
 by Pasteur at the close of the year 1888 to Sir Henry 
 Roscoe, that efibrts were being made in England to 
 obtain some public recognition, in the shape of a 
 fund, to testify in a substantial manner this country's 
 ofratitude for services received at the hands of the 
 Institut Pasteur. 
 
THE INSTITUT PASTEUR. 203 
 
 »H^ii>v K V\rv .W<(V . ioI^V-^^-tlU. (?,vu'ifl^ t^f/ir 5'm'T^ i^i^- 
 
204 PASTEUR. 
 
 (vfe^ Va, .--iJr-.VuSt . 
 
 Transcription of letter from M. Pasteur to Sir Henry Roscoe. 
 
 ''Paris le 23 Decemhre, 1888. 
 " Institut Pasteur, 
 
 "45, RueD'Ulra. 
 
 " Cher Sir, 
 
 "Je prie M. Yor. Horsley de vous faire remettre un 
 exemplaire du compte-rendu de notre seance d'inauguratioii le 
 14 Xovembre. Ce compte-rendu a paru hier seulement. Je 
 I'attendais pour vous ecrire et vous remerciertres cordialement 
 de I'initiative que vous avez bien voulu prendre en faveur de 
 rinstitut Pasteur. Une reponse favorable du Chancelier de 
 I'Echiquier, se traduisant par une participation effective du 
 parlemeut ou par toute autre voie dans votre pays, aurait un 
 effet moral considerable. Mais que penser de la reponse qui 
 vous a ete faite ? Est-ce une fin de non-recevoir 1 Laisse-t- 
 elle quelque espoir d'une issue favorable ? Se traduira-t- 
 
THE INSTITUT PASTEUR. 205 
 
 elle par une souscription publique parmi les hommes de 
 science, [)armi les savants et les medecins ? Quelle serait 
 rimpre&sion de Sir James Paget ? II n'y a rien a attendre des 
 X)ersonnes traitees. La tres grande majorite des personnes 
 mordues par des chiens enrages sont des ouvriers oil merne des 
 indigents. Et puis, la proximite de Londres et de Paris evite 
 au gouvernement anglais la depense d'installation et de fonc- 
 tionnement d'un laboratoire antirabique k Londres. Non 
 seulement la Russie a fait les frais de 7 cliniques de la rage, 
 mais le tsar a souscrit pour cent, mille francs. La Turquie 
 qui a peu de rage a fait les frais d'un laboratoire antirabique 
 et a souscrit pour 10,000 fr. L'ltalie a cinq laboratoires anti- 
 rabiques. Mila,n a souscrit dix mille fr. egalement, etc., etc. 
 Veuillez bien lire d'autres details dans labrochure de I'inau- 
 guration du 14 Novembre. En ce moment meme nous avons 
 plusieurs anglais en traitement. 
 
 "Quoiqu'il arrive, cher Sir Roscoe, je suis tres touche de 
 votre intervention dans cette affaire et vous en exprime toute 
 ma gratitude. 
 
 " Votre trfes devoue confrere, 
 
 "L. Pasteur. 
 
 "Si vous pensiez qu'une lettre de moi h M. le baron de 
 Worms serait utile, je pourrais lui ecrire. Pendant son sejour 
 a Paris, pour la Conference des sucres, j'ai eu I'honneur de le 
 voir, et il a rendu visite h nos inoculations et a parle meme h 
 un anglais en traitement le jour oil il est venu. II est 
 persuade que le gouvernement doit faire quelque chose pour 
 rinstitut Pasteur. Du moins, il m'avait alors jjarle dans ce 
 sens." 
 
 In July, 1889, these efforts were so far successful 
 that a public meeting was called at the Mansion 
 House, under the auspices of the Lord Mayor of 
 London, which was numerously attended by leading 
 men of science in the country ; whilst letters warmly 
 approving of its object were read from the Prince of 
 Wales, Professor Huxley, and other distinguished 
 gentlemen who were unable to be present. 
 
206 PASTEUR. 
 
 Huxley, after regretting his enforced absence from 
 the meeting, writes : " I find it difficult to imagine 
 that our wealthy country should be other than 
 ashamed to continue to allow its citizens to profit by 
 the treatment freely given at the Institute, without 
 contributing to its support. The oj^position . . . 
 which is threatened . . . proceeds partly from the 
 fanatics of laissez faire, who think it better to rot 
 and die than to be kept wdiole and lively by State 
 interference ; partly from the blind opponents of 
 properly conducted physiological experimentation, 
 who prefer that men should suffer rather than rabbits 
 and dogs." 
 
 The following are the resolutions which w^ere 
 moved and carried at the Mansion House : — 
 
 I. That this meeting desires to express the gratitude of the 
 people of Great Britain and Ireland to M. Pasteur and the 
 staff of the Institut Pasteur for the generous aid afforded by 
 them to over 200 of our fellow-countrymen suffering from the 
 bite of rabid dogs. 
 
 II. That this meeting, having heard the statements of Sir 
 James Paget and others, records its conviction that the efficacy 
 of the antirabic treatment discovered by M. Pasteur is 
 demonstrated, and requests the Lord Mayor to establish a 
 fund for the double purpose of making a suitable donation to 
 the Institut Pasteur, and of providing for the expenses of 
 British subjects unable to pay the cost of a journey to Paris 
 when bitten by rabid animals. 
 
 III. That this meeting, whilst recognising the value of M. 
 Pasteur's treatment, and taking steps to provide for its 
 accessibility to Englishmen who may hereafter be bitten by 
 rabid animals, is of opinion that rabies can easily be stamped 
 out in these islands, and calls upon the Government to intro- 
 duce at once a Bill for the simultaneous muzzling of all 
 dogs throughout the Ikitish Islands, as provided in the 
 
THE INSTITUT PASTEUR. 207 
 
 measure drafted by the Society for the Prevention of Hydro- 
 phobia. 
 
 In the Annales de VInstitut Pasteur for July, 
 1889, these resohitions are reproduced in full, without 
 comment, but the following significant lines are 
 added at the end : — " Profitons de cette excursion en 
 dehors de notre domaine, pour annoncer la creation 
 de deux nouveaux instituts antirabiques, — I'un a 
 Mexico sous la direction de M. Liceaga, et I'autre a 
 Bologne sous la direction de M. le professeur Murri." 
 
 Pasteur's letter to the Lord Mayor, acknowledging 
 the receipt of a copy of the above resolution, is so 
 characteristic that we have given it almost in its 
 entirety : — 
 
 " If the aphorism that science has no country has never 
 received authoritative sanction, it did so at this meeting, in 
 which the leading savants in biological and medical science of 
 the United Kingdom took part. I wish I could thank them 
 individually for having attended this gathering. I was filled 
 with gratitude on learning that the Prince of Wales himself 
 had accorded his high approbation of your initiative. Modesty 
 compels me to x^ass over in silence the kind words of which my 
 labours and those of the Pasteur Institute have been the 
 subject, but I have a right to rejoice with all friends of the 
 progress of humanity at the great moral effect of the meeting. 
 The manifestation of July 1st had not only for its object the 
 question of the treatment and possible extinction of hydro- 
 phobia in England, but in the nature of things it was also a 
 protest against that false sentiment which led certain persons 
 not merely to put on the same footing the life of men and that 
 of animals— which was already a strong point with them — 
 but even to prefer the existence of animals to the salvation of 
 human life. When this view is taken, what is the limit ? We 
 must become firm vegetarians. We must even exteiid our 
 scruples so that no living being is sacrificed. We must endure 
 the importunities of a mosquito, the daring of a mouse, the 
 
208 PASTEUR. 
 
 bite of a flea— false ideas or excuses for a tirade which one 
 finds most often at the root of all the attacks on experi- 
 mental physiology. 
 
 "Certain credulous souls— through I know not what tales — 
 imagine that our laboratories are chambers of torture. They 
 ignore the fact that the rabbit or the guinea-pig is rendered 
 insensible by chloroform before it is subjected to the most 
 insignificant operation. 
 
 "As for me personally, the sufi*ering of an animal affects 
 me so much that I would never shoot a bird, and the cry of a 
 wounded skylark pierces me to the heart ; but if the investiga- 
 tion of the mysteries of Nature and the acquisition of new 
 truths be at stake, the sovereignty of the object justifies all. 
 
 "Who, then, having the least regard for the pursuit of the 
 knowledge of the mysteries of Nature, would put in the 
 balance the sacrifice of a few fowls and rabbits with the 
 discovery of the attenuation of virus and prophylactics which 
 have resulted from such sacrifice? No one, my Lord Mayor, 
 will have contributed more than you have done to rectify the 
 errors which, under a show of compassion, can only hinder the 
 progress of science, and compromise even the most legitimate 
 interests of humanity." 
 
CHAPTER XYI. 
 
 CLOSING YEARS. 
 
 We have seen that the strain of work and anxiety 
 connected with the anti-rabic inoculations told so 
 severely upon Pasteur's weakened health that he was 
 practically compelled to bid farewell to those studies 
 which had for so many years engrossed his whole 
 attention, and the eager pursuit of which, during 
 nearly half a century, had brought that inexorable 
 toll of physical suffering which overshadowed the later 
 years of his life, but could not sully the brightness 
 of his intellect or dull the keenness of his perception. 
 
 The following striking personal impression pro- 
 duced by Pasteur was written but a short time before 
 his death by one intimately acquainted with him : — 
 
 " Everyone knows that Pasteur is short, that since 
 1870 his leg and left arm, smitten by apoplexy, are 
 somewhat stiff, and that he drags one foot much like 
 a wounded veteran. Age, illness, the heavy labours of 
 so many years,^ the bitterness of conflict, the intense 
 
 * It may not be witbout interest to briefly refer to tbe record of 
 publisbed work whicb Pasteur has left behind him. Besides nearly 
 two hundred notes and memoirs inserted in the " Annales de Chimie et 
 de Physique," in the " Comptes Rendus " of the Academy of Sciences, 
 in the " Recueil des Savants Strangers, " etc., Pasteur published 
 separately "Nouvel Exemple de Fermentation determinee par des 
 Animalcules infusoires pouvant ^-ivre sans Oxygene Libre" (1863) ; 
 " Etudes sur le Yin, ses Maladies, Causes qui les provoquent, Procedes 
 Nouveaux pour le Conserver et pour leVeillir" (1866); " Nouvelles 
 
 N 
 
210 PASTEUR. 
 
 passion for his work, and, lastly, that prostration 
 which follows triumph, have combined together to 
 make a grand thing of his face. 
 
 " Weary, traversed with deep furrows, the skin 
 and beard both white, his hair still thick, and nearly 
 always covered with a black cap; the broad forehead 
 wrinkled, seamed with the scars of genius, the mouth 
 slightly drawn by paralysis, but full of kindness, all 
 the more expressive of pity for the sufferings of others, 
 as it appears lined by personal sorrow ; and, above 
 all, the living thought v\diich still flashes from the 
 eyes beneath the deep shadow of the brow — this is 
 Pasteur as he appeared to me : a conqueror, who 
 will some day become a legend, whose glory is as 
 incalculable as the good he has accomplished." 
 
 Few men have during their lifetime received the 
 public recognition for their labours which was accorded 
 to Pasteur. This recoo-nition, moreover, was not con- 
 fined to his own country, but honours were showered 
 
 Etudes sur la Maladie des Vers a Soie" (1866); "Etudes siu- le Vin- 
 aigre, sa Fabrication, ses Maladies, Moyen de les Prevenir" (1868); 
 "Etudes sur la Maladie des Vers a Soie, Moyen Pratique Assure 
 de la Combattre et d'en Prevenir le Retour" (1870, 2 vols.) ; "Quelques 
 Reflexions sur la Science en France" (1871); ''Une Correspondance 
 entre un Savant Fi-anc^-ais et un Savant Prussien pendant la Guerre 
 — M. Pasteur et M. Naumann" (1872); Etudes sur la Biere, ses 
 Maladies, Causes qui les Provoquent ' (1876) ; "Les Microbes 
 organises, leur Role dans la Fermentation, la Putrefaction et la 
 Contagion" (1878); "Examen Critique d'un Ecrit Posthume de 
 Claude Bernard sur la Fermentation" (1879); "Discours de Reception 
 de M. L. Pasteur a I'Academie Fran(;aise" (1882); "Traitement de la 
 Rage" (1886); " Resultats de I'Application de la Methode Pasteur 
 prevenant la Rage apres Morsure " (1886); " Discoiu-s a I'Academie 
 Fran(,'aise a la Reception de M. J. Bortrand" (1887); " Discours pro- 
 nonce a rinauguration de la Statue de J. B. Dumas, ^ Alais " (1889). 
 
CLOSING YEARS. 211 
 
 upon him by numerous foreign public and scientific 
 })odies. Thus, to briefly summarise some of these 
 distinctions, we find him a member of the Academy 
 of Sciences in 1862 ; Honorary Doctor of the Medical 
 Faculty of the University of Bonn in 18^8 ; Foreign 
 Member of our Royal Society in 1869; an Associelibre 
 of the Academy of Medicine in 1873 ; Member of the 
 French Academy in 1881 ; a D.C.L. of Oxford in 1883 ; 
 Perpetual Secretary of the Academy of Sciences in 
 1887 ; whilst among the various medals and other 
 prizes bestowed upon him we find the Rumford Medal 
 of the Royal Society in 1856 ; the Copley Medal of the 
 same society in 1874 ; a prize of 10,000 francs from 
 the Austrian (lovernment in 1868, in recognition of 
 his researches on the diseases of silkworms ; a prize 
 of 12,000 francs in 1873 from the Societe d'Encourage- 
 ment; a medal from the Russian Society of Rural 
 Economy in 1882 ; the Albert Medal from the Society 
 of Arts, also in 1882 ; the Bressa Prize of 12,000 francs 
 from the Turin Academy of Sciences in 1888, etc. • 
 whilst in 1874 the French Government voted him an 
 annual pension of 12,000 francs, which in 1883 was 
 raised to 25,000 francs, with the further proviso that 
 on his death it should be continued to his widow and 
 children. 
 
 Pasteur was also the recipient of numerous orders. 
 Thus, Chevalier of the Legion of Honour in 1853, he 
 became successively Officier in 1863, Commandeur in 
 1868, Grand Officier in 1878, and Grand Croix in 1881. 
 A large number of orders were also bestowed upon 
 him by foreign countries, amongst which were Russia 
 Denmark, Greece, Brazil, Sweden, Turkey, Norway 
 and Portugal. 
 N 2 
 
212 PASTEUR. 
 
 If his life was darkened by struggles, it was equally 
 illuminated with brilliant victories, Avhich Pasteur 
 not only prized on account of the vindication of the 
 truths for which he fought and for the love of 
 science, but^ also for the lustre which they shed 
 upon his country. 
 
 " Si la science n'a pas de patrie," has said Pasteur, 
 " Thomme de science doit en avoir une, et c'est a elle 
 qu'il doit reporter I'influence que ses travaux peuvent 
 avoir dans le monde." 
 
 It was in this sense that Pasteur participated with 
 such profound feelings of emotion and gratitude in 
 the magnificent ceremony of his jubilee which took 
 place on December 27th, 1892, in celebration of his 
 seventieth birthday. 
 
 Early in the year already a committee was formed 
 in Denmark for the purpose of opening a national 
 subscription to present Pasteur with a medal com- 
 memorating his discoveries. The Medical Society of 
 Christiania followed suit and organised a public sub- 
 scription to enable a scholarship to be founded which 
 should be called after Pasteur, and provide the means 
 for a student to complete his scientific studies in some 
 foreign institute, and preferably in France. A similar 
 movement with a like object was started in Stockholm. 
 Throughout France all sections of society were united 
 in the desire to worthily honour their great country- 
 man. 
 
 The occasion was observed in Paris as a greatj 
 almost a national festival. The President of the 
 Republic and all the Ministers of State were present, 
 the members of the Institute of France, innumerable 
 delegates of foreign as well as French scientific bodies. 
 
CLOSING YEARS. 213 
 
 deputations from agricultural, pharmaceutical, veter- 
 inary and other colleges, and an inmiense gathering 
 of admirers, as well as students from all parts of the 
 country. In fact the large amphitheatre of the 
 Sorhonne. placed at the disposal of the organising 
 committee, capable of holding 2,500 persons, Avas 
 crowded to overflowing, as many as 4,000 requests for 
 places having been received. 
 
 The list of speakers included M. Dupuy, the Min- 
 ister of Public Instruction, M. d'Abbadie, President of 
 the Academy of Sciences, M. Joseph Bertrand, the 
 perpetual Secretary of the Academy of Sciences, Sir 
 Joseph, now Lord Lister (representing the Royal 
 Societies of London and Edinburgh), the perpetual 
 Secretary of the Academy of Medicine, and the Pres- 
 ident of the Municipal Council of Paris. 
 
 After these gentlemen had delivered their various 
 orations M. Bertrand introduced the delegates who 
 had been entrusted with addresses of congratulation 
 from the University of Athens; the medical faculty 
 and the Medical Society of Berlin ; the Medical 
 Society of Berne ; the Belgian Microscopical Society ; 
 the Society of the Students of the Civil Hospitals in 
 Brussels ; from Bucharest ; the Academic College, and 
 the University of Christiania; the Hygienic Association 
 of Cologne ; the Academy of Copenhagen ; the Royal 
 Irish Academy and University ; the Faculty of Medi- 
 cine of Ghent ; the Academy of Medicine and the 
 Medical Society of Geneva ; the L^niversity and the 
 Faculty of Genoa ; the University of Lausanne ; the 
 Faculty of Sciences and the LTniversity of Liege ; 
 from Leyden ; from Posen ; from the School of Medi- 
 cine and Faculty of Sciences of Stockholm. 
 
214 PASTEUR. 
 
 Then followed delegates from tlie Academy of 
 Sciences ; the Medical Society and the Society of 
 ^aturahsts of St. Petersburg; from the Russian 
 Students of the Institute of Experimental Medicine 
 in St. Petersburg ; the Turin Acadeni}^ of Medicine ; 
 the University of Utrecht ; and the Medical Society 
 of Warsaw. 
 
 Thus strikingly did nations forget politics, and 
 meet together to do honour to one of the greatest 
 men of science of the century. 
 
 After the foreign delegates had handed their ad- 
 dresses and had filed past the table, behind which sat 
 Pasteur, supported by the President of the Republic, 
 the national delegates were summoned, amongst 
 which were representatives from the towns of Dole 
 and Arbois, where, it will be remembered, Pasteur 
 was bom and had passed his childhood respectively. 
 
 Then followed the Students' Association of Paris, 
 represented by their President. 
 
 It was now Pasteur's turn to address the great 
 assembly, but being so much overcome by his feelings, 
 his speech was actually read by his son. 
 
 In itself a sufficiently pathetic speech, delivered in 
 the wmter of his life, though at the zenith of his fame, 
 it assumes a yet more pathetic significance inasmuch 
 as it proved to be the last public address which 
 Pasteur gave before his death. 
 
 "Monsieur le President de la Republique. — Your 
 presence transforms everything : a family fete becomes 
 a public fete, and the simple anniversary of the birth 
 of a savant, thanks to you, will remain a date in 
 French science. 
 
 " Monsieur le Ministre, Messieurs — My first thought 
 
CLOSING YEARS. 215 
 
 in the midst of this brilHant scene carries me back 
 with melancholy to the memory of the many men of 
 science who have known nothing but trials. In the 
 past they had to contend against prejudices which 
 stifled their ideas. These prejudices vanquished, they 
 encountered obstacles and difficulties of all kinds. 
 
 " Still but a few years since, before public author- 
 ities and the Municipal Council had given magnificent 
 dwellings to science, a man whom I greatly loved and 
 admired, Claude Bernard, had, only a short distance 
 from here, nothing but a damp and low cellar as a 
 laboratory. Perhaps it was there that he was attacked 
 with the malady which removed him from us ! 
 
 " On learning what you had here arranged for me, 
 the thouo'ht of him arose at once before me : I salute 
 this great memory. 
 
 " Gentlemen, through an idea, at once delicate and 
 ingenious, it would seem that you desired that my life 
 in its entirety should to-day pass before my eyes. 
 One of my countrymen from the Jura, the Mayor of 
 the town of Dole, has presented me with a photograph 
 of the very humble house where my father and 
 mother lived and struggled. 
 
 " The presence of all the students of the Ecole 
 Normale brings back to me how dazzling was my first 
 enthusiasm for science. 
 
 " The representatives of the faculty of Lille recall 
 to me my first studies in crystallography and fer- 
 mentation, which opened up an entirely new world 
 to me. With what hopes I was filled Avhen I first 
 surmised that there were laws behind so many 
 obscure phenomena ! By w^hat series of steps it was 
 permitted to me, as a disciple of the experimental 
 
216 PASTEUR. 
 
 method, to pass on to physiological studies, you, my 
 dear colleagues, have yourselves been witnesses. If I 
 have sometimes disturbed the peace of our Academic 
 meetings by somewhat too lively discussions, it is 
 because I have passionately defended the truth. 
 
 " You, lastly, delegates of foreign nations, who have 
 come from so far to give proof of your sympathy with 
 France, you bring me the deepest happiness which a 
 man can experience who believes invincibly that 
 science and peace will triumph over ignorance and 
 war, that people will learn to agree together, not for 
 purposes of destruction but for improvement, and 
 that the future will belong to those who shall have 
 done the most for suffering humanity. I address 
 myself to you, my dear Lister, and to all of you 
 illustrious representatives of Science, of Medicine, and 
 of Surgery. Young people, young people, confine 
 yourselves to those methods, sure and powerful, of 
 which we as yet know only the first secrets. And all, 
 whatever may be your career, never permit yourselves 
 to be overcome by scepticism, both unworthy and 
 barren; neither permit the hours of sadness which 
 pass over 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 T done 
 for my country ? ' so that some day that supreme 
 happiness may come to you, the consciousness of 
 having contributed in some measure to the progress 
 and welfare of humanity. But whether our endeavours 
 are more or less favoured by the circumstances of our 
 life, on approaching the great end we must have the 
 right to say to ourselves, ' I have done what I was able.' 
 
CLOSING YEARS. 217 
 
 " Gentlemen, I express to you my profound emotion 
 and my deep gratitude. Whilst on the reverse of this 
 medal,* the great artist Koty has hidden beneath roses 
 the date which now weighs so heavily on my life, so 
 you have desired, my dear comrades, to give to my 
 old age the spectacle which is capable of once more 
 gladdening it — this gathering of youth so full of life 
 and affection." 
 
 Dr. Roux has told us how the never-to-be-forgotten 
 ceremony of his jubilee, in showing Pasteur the place 
 he held in the esteem of the whole scientific world, 
 moved him profoundly. " Puis Pasteur ne vecut plus 
 que par I'amour des siens ; il fallait les soins et toute 
 Taffection dont il etait entoure pour prolonger sa 
 faiblesse. Mais jusqu'a la fin sa pensee etait dans les 
 laboratoires, avec ceux qui faisaient tons leurs efforts 
 pour que la maison qui porte son nom restat digne 
 de lui." 
 
 It was in September, 1895, that the news of 
 Pasteur's o-rave state of health o'ave cause for universal 
 anxiety. 
 
 A paralytic seizure, followed by a second attack a 
 week later, coming upon him in his already enfeebled 
 condition, led the worst to be anticipated, and on the 
 28th of September he passed awa}^ at Yilleneuve- 
 I'Etang, near Garches (Seine-et-Oise). 
 
 The body was embalmed and brought to Paris on 
 October 1st, where it was received in the name Of the 
 Government by M. Poincare, the Minister of Public 
 Instruction, and was placed in a room of the Institut 
 
 * A gold medal presented to Pasteur, designed by M. Eoty, and the 
 funds for which, were raised by international subscriptions. 
 
218 PASTEUR. 
 
 Pasfceiir which was temporarily transformed into a 
 chapel. 
 
 A public funeral at Notre Dame with military 
 honours was accorded to Pasteur by the State, 
 and took place amidst great pomp and ceremony 
 on October 5th. His body was, however, only 
 temporarily placed in one of the chapels of Notre 
 Dame, for Pasteur's final resting-place was to be in 
 the Institut Pasteur.* Hither it was brought at the 
 beginning of January, and was deposited in the 
 mausoleum which was erected by the Pasteur family. 
 
 The tomb f is built at the end of a long corridor 
 in the Institute, and is shut off by magnificent gates 
 of wrought-iron. Tlie archway over these gates is 
 decorated with irises on a gold ground, and the 
 simple words are inscribed, " Ici repose Pasteur," 
 
 * PASTEUR'S GRAVE. 
 
 No cypress-shadowed churchyard, nor the gloom 
 Of haunted cloisters, doth immortalise 
 The dust of him whose patience proved more wise 
 To save than Death to slay. The busy loom 
 Glancing with silk, the teeming herd, the bloom 
 Of purpling vineyards, and the grateful eyes 
 Of souls reprieved at Death's most dread assize, 
 Shall make eternal gladness round his tomb. 
 Not 'mid the dead should he be laid asleep 
 Who wageth still with Death triumphant strife, 
 Who sowed the good that centuries shall reap, 
 And took its terror from the healer's knife ; 
 Defender of the living, he shall keep 
 His slumber in the arsenal of life." 
 
 Alfred Hayes. 
 
 t The well-known tomb of Galla Placidia at Ravenna served as 
 the model for the mausoleum. 
 
CLOSING YEARS. 219 
 
 whilst on either side of it are recorded the dates of 
 his birth and death— " 1822-1895." Passing through 
 the gates, the crypt is reached by a flight of nine 
 steps of white statuary marble. The pavement of 
 the crypt is of marble mosaic on which are repre- 
 sented large wreaths of laurel. The crypt itself is 
 formed by four arches which support a cupola, and in 
 the centre is placed the sarcophagus, which is carved 
 out of a single block of dark-green porphyry. The 
 arches are supported on four groups, each of three 
 columns, two of green porphyry and one of red, with 
 Byzantine capitals of white marble. The walls are 
 lined with a cream-coloured marble, richly veined in 
 black, and above it are beautifully-executed mosaics. 
 
 On the marble which fills the arches on the right 
 and left are inscriptions indicating Pasteur's discoveries, 
 in historical order, as follows : 
 
 PASTED Pv. 
 
 1848 
 
 Dyssymetrie Moleculaire 
 
 1857 
 
 Fermentations 
 
 1862 
 
 Generations dites Spon- 
 
 TANEES 
 
 1863 
 
 Etudes sur le Vin 
 
 1865 
 
 Maladies des Vers a Soie 
 
 1871 
 Etudes sur la Biere 
 
 1877 
 Maladies Virulentes 
 
 1880 
 Virus Vaccins 
 
 1885 
 Prophylaxie de la Rage 
 
 Beyond the sarcophagus is an apsidal chapel con- 
 taining an altar of white marble, enclosed by a 
 balustrade of the same material. Above the staircase 
 
220 PASTEUR. 
 
 are inscribed the following words, taken from the 
 oration delivered by Pasteur at his reception into the 
 Academy of Science : — " Heureux celui qui porte en 
 soi un dieu, un ideal de beaute, et qui lui obeit — ideal 
 de Tart, ideal de la science, ideal de la patrie, ideal 
 des vertus de I'Evangile." 
 
 In the apse is another inscription : — " Ce monu- 
 ment fut eleve en MDCCCXCVI. a la memoire de 
 Pasteur par la piete de sa veuve et de ses enfants." 
 
 The mosaics, executed by A. G. Martin, represent 
 fowls, cattle, sheep, and dogs, indicating Pasteur's re- 
 searches on chicken cholera, anthrax, and rabies. There 
 are also designs of hops, vines, and mulberry trees, with 
 silkworms and moths, representing his investigations 
 on the diseases of beer and wine and silkworms. 
 
 Pasteur was a devout Roman Catholic, and the 
 religious side of his character is indicated in the 
 mosaics by angelic figures of Faith, Hope, Charity, 
 and Science, and, above the altar, by the figure of a 
 dove descending, representing the Holy Spirit, and 
 on either side the Greek letters A and 12. 
 
 Here rest, then, the mortal remains of that great 
 man of whom Renan once eloquently said : 
 
 " His scientific life is like a luminous trail in the 
 great night of the infinitely little, in those ultimate 
 abysses of being where life is born." 
 
INDEX. 
 
 Academy of Sciences, The, Arbitration 
 Commission appointed ijy, 6:i ; Pasteur 
 elected a meml^er of, 6J. 
 Acetic bacteria, Mr. Adrian Brown's work 
 
 on, 7-'. 
 Acetic fermentation, 68-76. 
 Aerobic liacilli, 50, 68 et seq. ; anthrax, 13S ; 
 
 Pasteur's experiments on. 139. 
 Air, Variation in ricliness of germ life, 59, 
 
 113. 
 Alais, Pasteur's work on the silkworm 
 disease at, 88 ; the statue of Pasteur at, 
 103, 104. 
 Akoholic fermentation, 37, 42-44, 114. 
 Amyl alcohol, 40. 
 
 Anaerobic life. Discovery of, 44-52; atmo- 
 spheric oxygea and, 50 ; malignant 
 oedema, 138. 
 Anthrax: Extent of the disease, 131; its 
 infection, 131, 133, 135 ; the Commission 
 of Eure and Loir, 131 ; effect of inocula- 
 tion with diluted blood, 1.33; disease due 
 to the bacilli proved by Pasteur, 137 ; 
 atmospheric oxygsn necessary to de- 
 velopment of the liacilli, 138 ; changes 
 in the blood shortly after death 
 through, l."8 : action of anaerol)ic 
 bacilli upon, 140 ; effects of heat and 
 cold upon, 140 ; Dr. Roux on Pasteur's 
 researches, 146 ; germs found in earth- 
 worms, 147; discovery of the vaccine, 
 154 ; inoculations, 158 et seq. 
 Anthrax researches, I3(i ; of Rayer, 1l'3, 131, 
 132; of Davaine, 123, 1.31, 1.32, 137; of 
 Pasteur, 27, 1.32, ia5 ; of Klebs, 134 ; of 
 Jaillard, 1.34,137; of Leplat, 134,137; of 
 Giliier, 141; of M. Chamberland, 155, 
 158-161,194. 
 Antiseptics, Introduction of, 124. 
 Antitoxin in diphtheria. The use of, 192. 
 Ants as carriers of moulds and yeasts, 121. 
 Arbitration Commisslnu appointed by the 
 Academy of Sciences, 62 ; Pasteur's 
 challenge to Lieliig, 75. 
 Arbois, Pasteur's home at, 9. 
 Aspartic acid, Dessaignes' reputed con- 
 version of fumaric and maleic acids 
 into, 28 ; refuted by Pasteur, 28. 
 Asymmetric bodies cannot be artificially 
 prepared, 29 ; Pasteur's experiments 
 on, 29. 
 Athens, Pasteur Institute at, 195. 
 Atoms, Theory of ari-angement in space 
 
 of, 22-24. 
 Australia's acknowledgment of Dr. Cal- 
 
 mette's work on snake poisons, 197. 
 Austrian Government, Award by the, 103, 
 
 Bacilli, Efljct of air upon, 4S, 153; rod 
 forms of, 42, 68, 101, 133 ; filtering 56, .58, 
 134 ; function of, 68 ; discovery of spore 
 ft'rm of. IW; retention of vitality in 
 the spores of, 101, 139; effect of heat 
 and C'lld upon, 112, 140; of anthrax, 
 131, 133 et seq. ; modes of reproduction, 
 i;^5 , of malignant oedema, 138, 139 ; 
 action of ae 'oijic and anaerobic upon 
 each other, 140 ; of puerpemi fever, 142, 
 
 143 : of fowl cholera, 15o. 162 ; of yellow 
 fever, 184; of diphtheria, 197; of 
 plague, 199. 
 
 Bacteria : Culture, 128.-144. 170 : staining of, 
 
 144 : Koch's treatise on, 144; media for 
 isolation and cultivation of, 145. 
 
 Bac'eriological research, 144 et seq. 
 
 Balard, Pasteur's studies under, 12. 
 
 Basnau, Dr , ana spontaneous generation, 
 64. 
 
 Beer, Srudies on, 108-122; summary of in- 
 vestigations, 111. 
 
 Berlese, Dr.. on the dissemination of 
 yeasts, 121. 
 
 Berlin Academy of Sciences and Pasteur, 
 109. 
 
 Bertiand.M., at the opening of the Pasteur 
 Institute, 187. 
 
 Besan<jon CoUcge, Pasteur at the, 11. 
 
 Biot. Discoveries in polarisation of light, 
 14 ; and Pasteur, experiments ou the 
 tartaric acids, 20. 
 
 Bonn University, award to Pasteur, 103; 
 his letter returning the diploma, 108. 
 
 Boyle on fermentation phenomena. 127, 128. 
 
 Brazil, Reward offered for the discovery of 
 a cure for yellow fever, 183. 
 
 Brefeld and gelatine cultures of bacteria, 
 145. 
 
 Brewers' tribute to Pastenr, The, 112. 
 
 Brown, Mr. Adrian, 72. 
 
 Buchner and alcoholic fermentation, 116. 
 
 Butyric ferment. Observations on, and the 
 effect of atmospheric osyaren upon the 
 bacilli, 45 ; compared with acetic fer- 
 ment, 68. 
 
 Cagniard-Latour, Investigation on fermen- 
 tation, .36 et (■eq., 71. 
 
 Calmette, Dr., 196. 
 
 Carlsberg. The laboratory at, 11.3. 
 
 Chamberland, Experiments with anthrax 
 vaccine, 155, 158-161, 194, 
 
 Cholera gallinarum, 150, 162. 
 
 Crystals, Pasteur's experiments with, 16 
 et seq. ; of tartaric acid, 17. 
 
222 
 
 INDEX. 
 
 Cultures, Pure, by successive inocula- 
 tions. U'8; selectiou of media, 128, 144 ; 
 in gelatine, 145 ; of virus of rabies in 
 the living brain, 170. 
 
 Darlav and Pasteur, 11. 
 
 Davaine, Work on anthrax, li'3, 132, 137; 
 memoir publislied, 131. 
 
 Delafosse and Pasteur, 14. 
 
 Demfttium, ll'J. 
 
 Desfaignt's memoir refuted by Pasteur, 28. 
 
 Dijon, Pasteur at, 20. 
 
 Dii>htheriH. The use of antitoxin in, 192. 
 
 Dissi metric forces, 18-22. 
 
 Doctors and scientific research, 126, 127, 142. 
 
 Duclaux, M., Director of the Pasteur In- 
 stitute, 191 ; letter to, from Pasteur, 109. 
 
 Dumas, Pasteur s studies under, 12 ; and 
 the silkworm ditease, 85. 
 
 Dusch's use of cotton wool for filtering 
 the air, 56, 58. 
 
 Ecole des Beaux-Arts, Pasteur's appoint- 
 ment to the, 83. 
 Ecole Normale, Pasteur at the, 12, 45. 
 Education, Higher, Pasteur and, 201. 
 
 Fermentation, Pasteur's study of 31-34, 40- 
 44 ; Liebig's theory of, 35, Sy ; protec- 
 tion from, by boiling, etc, 35; effects 
 of ox> geu upon, 35, 36, 38, 46 ; (jagniard- 
 Latour on the vital theory ol, 36 ; 
 yeast cells, 36; Schwann's investiga- 
 tions, 36 ; alcoholic, 37^43jjj4 ; caused 
 l)y vegetable organi!3wy,T5'7; decay and, 
 38; Helmholtz s experiment, 38; vital- 
 istic theory, 39, 44. 73, 119-122; lactic, 
 41; transmissibility of prcjci ss, 42; 
 Pasteur's memoirs on lactic and alco 
 holic, 43 ; experiment with butyric, 46 ; 
 acetic and butyric, 68; Pasteur and 
 previous discoveries, 70; studies in 
 beer. Ill ; theCarlsberglaljoratory, 113; 
 "life without oxygen,"' 114; Buchner s 
 zvmase, 116, 
 
 Fischer, Emil, and artificial sugars, 23. 
 
 Flacht-rie, a disease of the silkworm, 99- 
 103 ; soiue 1 auses of, loi. 
 
 Fleury, :>L, on Dr. Roux's work, 193. 
 
 Flies, Bxperiiiitints with yeast upou, 122. 
 
 Fowls, Experiments with inoculation of 
 anthrax, 140; ch<jlera of, 149; cholera 
 bacillus. 150.162. 
 
 Frogs, Expenmenial anthrax inoculation 
 of, 141. 
 
 Gay-Lussac, 35, 38, 55, 58. 
 
 Gelatine for cultivation of bacteria, 145. 
 
 Germs, Sterilis ng infusions, 03 ; in the air, 
 
 59, 113; destroyed by heat, J 12. 
 Gernez, M..and Pasteur, 8«. lai. 
 Gil)ier on frogs and anthrax, 141. 
 Graine, or egg of silkworm iiioih, and its 
 
 connection with the diseases, 88 et seq. 
 Grancher, Dr., incjculates a Ijoy liitten l)y 
 
 rabid dog, 171 ; speech at the opening 
 
 of the I'asteur Institute, 187. 
 Grapes and yeasts, 119. 
 
 Hav and veast infusions. Comparison, 63. 
 Haves, Alfred, sonnet on Pasteur, 2I8. 
 Heiinholtz on fermentation and decay, 3s. 
 Hontf Kong plague, The, Yersin's investi- 
 
 g^Uions, 197-200. 
 Huxley and the Mansion House meeting 
 
 206. 
 Hydrophobia. (See Rabies. 
 
 Immunity, First researches in the domain 
 
 of, 149; artificial production of, 151. 
 Infection, from pebrine in silkworms. 96, 
 
 98; from flacherie, 100,103; by spores, 
 
 101 ; of anthr.ix, 131, i:a, 135 ; vitallstic 
 
 theory of, 134. 
 Infectious diseases. Introduction to the 
 
 study of, 123. 
 Insects and alcoholic ferments, 122. 
 Insects convey germs to plants, 121. 
 Institut Pasteur, The. 185 ; M. Henri 
 
 Pottevin's report, 180 ; opening of by 
 
 the President, 186. 
 Institute, British, of Preventive Medicine, 
 
 182. 
 
 Jaillard's experiments on anthrax, 134, 
 
 137. 
 Jenner, Pasteur's tribute to, 154 ; Herbert 
 
 Spencer and, 154. 
 Jbrgensen, Dr., 121. 
 
 Kleb's researches on anthrax, 1.34 ; use of 
 
 pelatine by, 145. 
 Koch, Robert, researches on anthrax, 1.34, 
 
 l.3fi; his treatises on bacteria and on 
 
 infection, 144 ; media for isolation and 
 
 cultivation, 145. 
 
 Laffemas, valet to Henry IV". of France, 
 and silkworm culture, 102. 
 
 Latour, Cagniard-, .?<>, 
 
 Leplafs experiments with anthrax, 131, 
 137. 
 
 Liebig's theory of fermentation, 35 ; con- 
 troversy on the vitalistic theory, 39, 49 
 73-76; his theory refuted by Pasteur,, 
 42-44. 7.3. 
 
 Lille, Pasteur at, 34. 
 
 Lister and antiseptics, 124 ; his tribute to 
 Pasteur, 124. 
 
 Local Government Bonrd and Pasteur's 
 treatment of rabies, 173. 
 
 Mains, Discovery of the polarisation of 
 light by, 14. 
 
 Mansion House meeting and Pasteur's 
 work on rabies, 202 et seq. 
 
 Medical men and research, 126, 127, 142. 
 
 Meister, the first hunun being inoculated 
 for rabies, 171. 
 
 Meluii Agricultural .Socie'y, Pasteur's 
 demonstration with anthrax vaccine 
 before the, 158. 
 
 Memoirs, published by Pasteur, 209, 210. 
 
 Metchinkofl, Dr., 193. 
 
 Meze methods of heating wine. The, 82. 
 
 Micro-organisms in the economy of 
 nature, 51. 
 
 Milk souriiiff. Causes of. 42-44 ; sterilisa- 
 tion at 1 10° C. by Pasteur, 61. 
 
 Mill. .John Sruart, on mediocrity, 201. 
 
 Mitscherlich and Pasteur, 15, 16. 
 
 Molecular physics, Pasteur's researche-^ in, 
 14 et seq.: effects of the discoveries in 
 polarisation of light upon, 15 ; pheno- 
 mena exhibited by the tartaric acids, 
 22-.33. 
 
 Moulds, Oxidising action of 72, 115; mucor 
 miicedo. 111; peiiicilliian (jlaucum, 117; 
 supposed transformation into yeast, 
 114, 117 ; Uematinm, 119. 
 
 Mucor muccdo, J 14. 
 
 Mulberry, The effect of yearly pruning of 
 the, 102, 
 
INDEX. 
 
 223 
 
 Munich Academy, Liel)ig's papers on fer- 
 
 iiient!it.i()n at, tlio, 73. 
 Mycodc.nna vmi, 117. 
 Myciiderma acvti, Tlie IjacilhiH, (58 ; lic- 
 
 liaviour of, 7o. 
 
 Napoleon and Pa8(ciir, loii. 
 Ncodliaiii, Fatlicr, on sjujiit incoiis genera- 
 tion, .')4 ; Spallanzaui's controverijy, 55. 
 
 Orleans, Pasteur's address at, to vinegar 
 inanuractnrers, (>7. 
 
 Oxyg(!n, Eltects on fennentation, .'i.'i, !i(i, .^8; 
 bact.eiia icilled liy, -IG ; cxixiriments 
 with niicro-orKaiusnis, .'io ; oxidising 
 action of moulds, 72, ll."); and of liac- 
 teria, 68; fennentatiou — life without 
 oxygen, 114. 
 
 Paralysis, Pasteur's attack of, lol, 
 Paratartaric acid, Ixdiaviour under 
 polarised light. 10 «< se.q.; experiments 
 with fermentation, and physiological 
 character of, :!!, iVi. 
 Pasteur, Louis: Mirlh and childliood, !) ; 
 Bcliooling, 10; his favourite pastimes, 
 10 ; enters Uesancjon (ioHcgc, 11 ; at the 
 Ecole Normale, II'; his studies uiulcr 
 Dumas and Balard, 12; his habits of 
 mind, li', 13: ids industry asa stu<lonr,, 
 13; jntlucnce of Delafossi^ upon, 11; 
 experiments in polarisation of liglit, 
 14 ot seq.; and .Mitscherlich, I.'i, Hi ; and 
 Biot, 20; molecular tlicoiy, 22 <t scj/.; 
 chemical researcthcs, 2r>; at 1) jon, 20, 
 at Strassliurg, 20; marriage of, 20 ; con- 
 trovei.^y with Dessaigne, 28; researches 
 on fermentation, 31-52; awarded the 
 Rumford Medal by the Iloyal Society- 
 .32 ; at Lille, 31 ; Lieliig's theory of fer- 
 mentation rcifuted, 42-44 ; memoirs on 
 lactic and alcoholic fermentation, 43; 
 Director of the Kcole Normale. 45; 
 discovers bacilli killed l)y atmosplieric 
 oxygen. 46; controversy with Liebig. 
 49 ; exjieriments on micro-organisms in 
 leririentative and putrefactive pheno- 
 mena, .IO; spontaneous generation con- 
 troversy, 5.3-00; experiments on germ 
 life in air, .5!) ; ('ommission appointed 
 to arbitrate, 02; elected member of the 
 Acad(;my of Sciences, 64 ; studies on 
 the vinegar organisms, 07-70 ; address 
 at Orleans, 07 ; controversy with Liebig 
 renewed, 7.3-70 ; on souring of wine, 77- 
 82 ; on diseases of silkworms, 83-107 ; 
 his appointment to the lOcole des 
 Beaux-Arts, 83; at Alais, 88-105; death 
 of a daughter, 92 : recognition and 
 rewards from foreign countries, io3 ; 
 has an attack of paralysis, 104; I'hu- 
 peror Napoleon and, 100; studios on 
 beer, 108-122; at Clcrmont-Kerrand, Uo ; 
 work on yerists and moulds, lt4-l'!2; 
 study of infectious diseases, 123; 
 Lister's tribute to, 124 ; I'rol". Tyndall 
 and, 125 ; anthrax researches, i:!5 ; 
 meiMoirs on anthrax and si'ptica^mia, 
 ]'!9; on immunity, 149; anthrax 
 vaccine, 155; his work on rabies, 103 ; 
 repugnatice to vivisection, 109 : his 
 daily routine of work, 175 ; at the 
 opening of the Pasteur Institute, 186; 
 and the Mansion House meeting, 207; 
 his closing years, 209 ; published works, 
 209; public recognition, 210; cercMuony 
 of his jubilee, 212 ; his speeidi in reply, 
 214; his death, 217 ; public funeral and 
 description of his tomb, 2I8. 
 
 Pasteur, Madame, 26, 92, 177, 178, 180. 
 
 P.'isteurisation, The process of,80. 
 
 IVbrine, a disease of the silkworm, 88. 
 
 /'eidcitli.ii,in t/laucinii,, 117. 
 
 Peter, M., opposes Pasteur's treat nient of 
 rabies, 172. 
 
 Phagocytosis, The theories of, 194. 
 
 Plants and carbonic acid, 74. 
 
 Polarisation of light, The: Mains' dis- 
 covery, 14; Biot's discoveries, 14 ; the 
 rotation of plane of polarisation, 15; 
 behaviour of crystals of the tartaric 
 acids under, 15 et seq. ; Mitscherlich 
 and Pasteur, experiments with, 15 ; 
 fermentation of the tartaric acids and 
 tlieir physiological dilferences shown 
 by, 31, 32. 
 
 Potie\in, M. Henri, report on the anti- 
 rabic inoculations, I80, 
 
 Pouchet s expei-iiiient on sponlaneous 
 generation, .5(>, 58, 59. (i;(. 
 
 Pouilly-le-Fort, Pasieur's experiments at, 
 
 159. 
 
 Puerperal fever. The biicillus of, 142, 14,3. 
 
 Rabies, invrstigation of, 103; microbe not 
 yet discovered, 105, lOii ; collecting 
 s;ili\a from dog. 107; attacks the nerve- 
 centres, 108; Dr. Uoux on Pasteur's 
 experiments, 109; inoculations, 17o ; 
 apiilication of the tr atmeiit to human 
 beings, 171 ; a London committee ap- 
 l)oinied to in((uire, 173; tables showing 
 mortality, 181 ; mi eiing :it the Mansion 
 House and P.asteur's work on, 202 at seq. 
 
 Rayer's work on anthrax, 123; memoir 
 published, 131. 
 
 R6nan on Pasteur, 220. 
 
 Research, .Scientillc, and public opinion, 
 201, 202. 
 
 Roux, Dr., on Pasteur's researches, 14'.', 140, 
 149, 150, 109, 174, 175, 201); his experi- 
 ments with jintlirax vaccine, 1.55, 1,58 
 et. seq. ; and his work at the Pasteur In- 
 stitute, 192. 
 
 Royal Society, The, and Pasteur's work, 
 
 103. 
 
 RMiiitord medal and Pjisteur, 32. 
 
 Sanarelli, Dr., and the yellow fever 
 bacillus, 184. 
 
 Schroeder's experiment repeated by 
 Pasteur in the spontaneous generation 
 controvtn'sy, .58. 
 
 Schwann's researclies on fermentation, .36; 
 :ind the spontaneous genenition con- 
 troversy, .5.5. 
 
 Hepticmviia, Pasieur's work on, 1,38, 1.39. 
 
 Shrooter's culture media, 1 15. 
 
 Silkworm diseases : Pasteur's researches 
 on the, 83, 87-107 ; the epidemic in 
 Krance,84; the government petitioned, 
 85 ; Dumas appointed to investigate, 
 85; Pasteur at Alais. 88; the signs or 
 PLMirine, 88; work of various observers 
 upon, 90 ; the microscopic corpuscles 
 of, BO; didlculties of the investigations, 
 9;i-97 ; infection of, 90, 98 ; discovery of 
 two diseases, 99; tlacheric, 99-103; pub- 
 lication of the history of the, loo. 
 
 Silkworms, lOxaminiug moths and sorting 
 healthy eggs of, 97 ; effects of char- 
 acter of muliierry leaves upon, 102. 
 
 Snake poison, Artillcial immunity from, 
 
 190. 
 
 Sp.'illanzani's experiments on fermenta- 
 tion, 35; and the spontaneous genera- 
 tion controversy, .5.5. 
 
 Spencer, Herbert, and Jenner, 154. 
 
224 
 
 INDEX. 
 
 Spontaneous generation controversy, The, 
 53 66 ; ancient tbeories of, 5.3, 54 ; Father 
 Needliaiii's experiment, 5-1, 55 ; Spallan- 
 zani's dissertation, 55 ; Schwann's appa- 
 ratus, 55 ; Pouchet's experiment, 56, 58, 
 59, 63 ; Bastian"s investigations, 64. 
 
 Spores, First discovery of, in pathogenic 
 bacteria, 201. 
 
 Staphplncoccus pyogenes. 142. 
 
 Strassiiurg University, Pasteur at the, 26 ; 
 appointed Deputy Professor of Che- 
 mistry at the, 26. 
 
 Sireptococcus pyoriencs, 142. 
 
 Swine measles, Researches on, 163, 195. 
 
 Tartaric acid under polarised light, i5 
 et )<eq.: crystals of, 17: Pasteur's ex- 
 perinients on crystals of. 19 ; fermenta 
 tion of, 31 ; physiological character, 32. 
 
 Thuillinr and Pasteur, 163. 
 
 Toussaint, 150. 
 
 Turpin and tlie vitalistic theory of fer- 
 mentation, 37. 
 
 Tyndall, Prof., and Pasteur, 125. 
 
 Urine, Pasteur's anthrax culture in, 1.36. 
 Uruguay, Honours conferred on Dr. Sana- 
 relli l)y,l84. 
 
 Vaccination with anthrax vaccine, l.W ; 
 
 public e.xpiriiuents at Pouiliy-le-Fort, 
 
 159 ; great demand for the vaccine, 
 
 160, 161. 
 Vaccine of anthrax, The discovery of the, 
 
 1.54; of fowl cholera, 152. 
 Vallery-Iladot, M., with Pasteur collect 
 
 saliva of labid dog, 167. 
 
 Van Helmont and spontaneous geueration, 
 
 54. 
 Vinegar, Studies on the organisms in, 67- 
 
 76 ; method of manufacture. 68 ; action 
 
 of the mycoderma aceti bacillus, 68-76 ; 
 
 German process of manufacture, 74. 
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