CREAM RIPENING 



189 



bacteria. As to the kinds of organisms found in ripened cream, 

 we have isolated B. acidi lactici, the predominating organism, and 

 B. lactis aerogenes. The latter organism does not increase very 

 much during the ripening process, and its part in the process is 

 obscure. In three or four days the number of organisms in cream has 

 abated, and eventually nothing remains but Oidiujn lactis, 2lS in milk. 

 In the experiments carried out by Conn and Esten it was 

 found that three types of lactic organisms predominated, when the 

 period of the acid increase arrived and which indicated ripening. 

 During the ripening B. acidi lactici increased uniformly, a second 

 form also appeared to increase in proportion, whilst B. lactis 

 aerogenes slightly declined. The alkaline or miscellaneous group 

 showed a universal decline as ripening proceeded.^ These points 

 are well illustrated in the two follovvinsr tables : — 



It should be stated that the miscellaneous group do not produce 

 acid, but otherwise have nothing in common. Some liquefy gelatine, 

 others do not Conn and Esten made a similar study of percentages 

 in cream from private dairies with the following result : — 



^ See also Zeit. f. Hyg., 1901, xxxviii., p. 387. Kozai finds three bacteria 

 associated with souring, the chief one apparently identical with Esten's B.ac. lact. 



