274 CITY MILK SUPPLY 



of gelatin liquefiers. Such species do not develop in raw milk nor in 

 Washington pasteurized milk pasteurized at 140 to 149F. for 30 to 35 

 min. only the ordinary lactic acid bacteria being found. 



6. How far these spore-bearing organisms play a role in the clinical 

 condition, especially that of children, is yet to be proved. 



In continuation of the Baltimore work Lawrence and Ford from 1913 

 to 1916 worked out the cultural reactions of 250 spore-bearing bacteria 

 isolated from 68 samples of milk, 12 of raw milk, 12 of milk pasteurized 

 at 140F., 32 of milk heated to 185F. and 12 of boiled milk. They 

 believe the cultures give an accurate idea of the spore-bearing bacteria 

 of the milk of Baltimore and probably of that elsewhere. By their com- 

 bined development in heated milk, these organisms give rise to the putrid 

 decomposition so often observed; in the majority of instances they are 

 energetic protein-splitters and in practically every case dissolve the pro- 

 tein in milk, either before or after a preliminary coagulation. 



After establishing the various types of organisms by the study of 

 250 cultures from the 68 samples, another series of milks, also subjected 

 to various treatments, was investigated with the object of testing the 

 preliminary classification adopted. The types were abundantly con- 

 firmed but no new organisms were isolated which indicates that the or- 

 ganisms represent the spore bearers usually present in Baltimore milk. 

 In the original 250 cultures the various species were found in the following 

 proportions : 



B. cereus FranklancL 124 



B. subtilis (Ehrenberg) Cohn 79 



B. albolactus Migula 25 



B. vulgatus (Fliigge) Trevisan 15 



(B. mesentericus vulgatus Fliigge) 



B. mesentericus (Fliigge) Migula 2 



(B. mesentericus fuscus (Fliigge) 



B. fusifomis Gottheil 2 



B. petasites Gottheil 1 



B. cohaerens Gottheil 1 



B. terminalis Migula 1 



Besides, the following spore-bearing species were isolated from other 

 sources which, partly from the work of others and partly because they 

 are not infrequent in milk products, the authors believe may occur in milk: 



B. mycoides Fliigge. 



B. megatherium De Barry. 



B. simplex Gottheil. 



B. aterrimus Lehman and Newmann (B. mesentericus niger Lunt). 



B. niger Migula (B. lactis niger Gorini). 



B. globigii Migula (B. mesentericus ruber Globig). 



Shippen investigated the growth of B. welchii in milk. He found 

 that when it is transferred to that medium with the common aerobic 



