78 THE STORY OF GERM LIFE. 



vours and aromas which they impart to the cream 

 and to the subsequent butter are those that are 

 desired. It is these decomposition products that 

 give the peculiar character to a high quality of 

 butter, and this peculiar quality is a matter that 

 determines the price which the butter maker can 

 obtain for his product. 



But, unfortunately, the butter maker is not al- 

 ways able to depend upon the ripening. While 

 commonly it progresses in a satisfactory manner, 

 sometimes, for no reason that he can assign, the 

 ripening does not progress normally. Instead of 

 developing the pleasant aroma and flavour of the 

 properly ripened cream, the cream develops un- 

 pleasant tastes. It may be bitter or somewhat 

 tainted, and just as sure as these flavours develop 

 in the cream, so sure does the quality of the but- 

 ter suffer. Moreover, it has been learned by ex- 

 perience that some creameries are incapable of 

 obtaining an equally good ripening of their cream. 

 While some of them will obtain favourable results, 

 others, with equal care, will obtain a far less favour- 

 able flavour and aroma in their butter. The rea- 

 son for all this has been explained by modern bacte- 

 riology. In the milk, and consequently in the 

 cream, there are always found many bacteria, but 

 these are not always of the same kinds. There 

 are scores, and probably hundreds, of species of 

 bacteria common in and around our barns and 

 dairies, and the bacteria that are abundant and 

 that grow in different lots of cream will not be 

 always the same. It makes a decided difference 

 in the character of the ripening, and in the conse- 

 quent flavours and aromas, whether one or another 

 species of bacteria has been growing in the cream. 

 Some species are found to produce good results 



