190 PASTEUR: THE HISTORY OF A MIND 



on crystals, on spontaneous generation, and on silk- 

 worms. At every instant his thoughts and his actions 

 got away from him without his being conscious of it, 

 attracted by some question which seemed to him more 

 important than the influence of the degree of aeration 

 of the must on the quality of the beer, and it is this 

 which we see in his book, where he attacks and solves a 

 multitude of questions which have only a remote con- 

 nection with the brewery. The studies on the trans- 

 formation of species, one into another, on the first origin 

 of the yeasts of the vintage, on the general theory of 

 alcoholic fermentation, fill three-fourths of the book. 

 His obviously desultory style renders its analysis difficult. 

 We shall consider it, en bloc, only as a document which 

 is of great value for the history of the scientific man who 

 composed it. 



There is another way of tracing the preoccupations 

 of Pasteur at this time; that is to examine the Comptes 

 rendus de I' Academic des Sciences. The Academy served 

 him both as a tribune from which to reply to his oppo- 

 nents without, and as a field of combat for the discus- 

 sions, sometimes picturesque, into which he entered with 

 some of his confreres. All this part of his life forms an 

 animated picture. Let us endeavor to trace the prin- 

 cipal facts without following strictly the chronological 

 order. 



II 



TRANSFORMATION OF ONE SPECIES INTO 

 ANOTHER 



There is in the beginning one part with which we are 

 already familiar, through having encountered it in its 

 proper place. That is the whole discussion with Bastian 

 on spontaneous generations, and with Liebig on the role 



