208 THE LIFE OF PASTEUR 



from a fresh source. In a book of reference which was then 

 much in use, entitled Alimentary Substances: the Means of 

 Improving and Preserving them, and of Recognizing their 

 Alterations, six pages were given up to beer by the author, M. 

 Payen, a member of the Institute. He merely showed that 

 germinated barley, called malt, was diluted, then heated and 

 mixed with hops, thus forming beer-wort, which was sub- 

 mitted, when cold, to alcoholic fermentation through the yeast 

 added to the above liquid. M. Payen conceded to beer some 

 nutritive properties, but added, a little disdainfully, " Beer, 

 perhaps on account of the pungent smell of hops, does not seem 

 endowed with stimulating properties as agreeable, or as likely 

 to inspire such bright and cheerful ideas, as the sweet and 

 varied aroma of the good wines of France." 



In a paragraph on the alterations of beer — "spontaneous 

 alterations " — M. Payen said that it was chiefly during the 

 summer that beer became altered. "It becomes acid, and 

 even noticeably putrid, and ceases to be fit to drink." 



Pasteur's hopes of making French beer capable of competing 

 with German beer were much strengthened by faith in his own 

 method. He had, by experimental proof, destroyed the theory 

 of spontaneous generation ; he had shown that chance has no 

 share in fermentations ; the animated nature and the specific 

 characteristics of those ferments, the methods of culture in 

 appropriate media, were so many scientific points gained. The 

 difficulties which remained to be solved were the question of 

 pure yeast and the search for the causes of alteration which 

 make beer thick, acid, sour, slimy or putrid. Pasteur thought 

 that these alterations were probably due to the development of 

 germs in the air, in the water, or on the surface of the numerous 

 utensils used in a brewery. 



As he advanced further and further into that domain of the 

 infinitely small which he had discovered, whether the subject 

 was wine, vinegar, or silkworms — this last study already open- 

 ing before him glimpses of light on human pathology — new and 

 unexpected visions rose before his sight. 



Pasteur had formerly demonstrated that if a putrescible 

 liquid, such as beef broth for instance, after being previously 

 boiled, is kept in a vessel with a long curved neck, the air only 

 reaching it after having deposited its germs in the curves of the 

 neck, does not alter it in any way. He now desired to invent 

 an apparatus which would protect the wort against external 



