362 LOUIS PASTEUR 



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the service which Pasteur has rendered to science in being 

 the first to indicate the exact relation of things in the 

 phenomenon of fermentation." In his later researches, Dr. 

 Brefeld has adopted the method which we have long em- 

 ployed for demonstrating the life and multiplication of 

 butyric vibrios in the entire absence of air, as well as the 

 method of conducting growths in mineral media associated 

 with fermentable substance. We need not pause to con- 

 sider certain other secondary criticisms of Dr. Brefeld. A 

 perusal of the present work will, we trust, convince him 

 that they are based on no surer foundation than were his 

 former criticisms. 



To bring one's self to believe in a truth that has just 

 dawned upon one is the first step towards progress; to per- 

 suade others is the second. There is a third step, less use- 

 ful perhaps, but highly gratifying nevertheless, which is, 

 to convince one's opponents. 



We therefore, have experienced great satisfaction in 

 learning that we have won over to our ideas an observer 

 of singular ability, on a subject which is of the utmost im- 

 portance to the physiology of cells. 



VI. REPLY TO THE CRITICAL OBSERVATIONS OF LIEBIG, 

 PUBLISHED IN 



IN the Memoir which we published, in 1860, on alcoholic 

 fermentation, and in several subsequent works, we were 

 led to a different conclusion on the causes of this very re- 

 markable phenomenon from that which Liebig had adopted. 

 The opinions of Mitscherlich and Berzelius had ceased to 

 be tenable in the presence of the new facts which we had 

 brought to light. From that time we felt sure that the 

 celebrated chemist of Munich had adopted our conclusions, 

 from the fact that he remained silent on this question for 

 a long time, although it had been until then the constant 

 subject of his study, as is shown by all his works. Sud- 

 denly there appeared in the Annales dc Chimie et de Physique 



1 LIEBIG, Sur la fermentation et la source de la force musculaire 

 (.Annales de Chimie et de Physique, 4th series, t. xxiii., p. 5, 1870). 



