1 



Pasteur received the intelligence, in October, 1857, that he had been 

 appointed Director of Scientific Studies at the Ecole Normale in 

 Paris. There being no scientific laboratory attached to the post, 

 Pasteur, unable to obtain any funds from the Government for such a 

 purpose, improvised one out of a garret in the building and equipped 

 it out of his own purse. Here he pursued with unabated energy the 

 investigations which his removal from Lille had temporarily inter- 

 rupted, and it was in the course of his further researches on fer- 

 mentation that he made a discovery which, in respect of its wide and 

 fundamental significance in relation to the economy of nature, is per- 

 haps without an equal amongst his numerons and great achievements. 

 This important discovery revealed the existence of 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. 



This new condition of existence, which he found pertained to the 

 butyric ferment, Pasteur called anaerobic, as opposed to aerobic life, 

 in which oxygen is essential to the continuance of life. This revo- 

 lutionary discovery raised a perfect storm of opposition, and Pasteur's 

 attitude to his opponents is well exemplified by the following words 

 of his own : — " Whether the progress of science makes of this vibrio 

 a plant or an animal it matters little, but it is a living thing, endowed 

 with movement, which lives without air, and is a ferment." 



This anaerobic life of the butyric ferment was not allowed to remain 

 an isolated 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 com- 

 munication to the Academy of Sciences, in which he develops in out- 

 line that celebrated theory of fermentation which has served to stimu- 

 late so many valuable researches. 



Pasteur in his investigation 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 ques- 

 tions. Secondly, he had worked out a method of scientifically 

 attacking these problems, in which, for the first time, both the chemi- 

 cal and biological aspects of the subject received their due share 

 of attention. 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 sufficient experi- 

 mental data to venture on a new theory of fermentation. 



The further researches which the new theory of fermentation 

 stimulated were deferred for some years in consequence of his atten- 

 tion being directed to certain phenomena closely related to fermenta- 



