10 



BULLETIN 342, U. S. DEPARTMENT OF AGRICULTURE. 



The bacterial flora of the various kinds of milk is represented in 

 figure 1 by columns of equal length divided into sections, which, in 

 a general way, show the relative proportion of the bacterial groups. 



From the figure it may be seen that raw milk contains four prin- 

 cipal groups of bacteria— the acid, inert, alkali, and peptonizing 





C04GC/L/7T//VG 

 G/KH/S? 



G/?Oi//? 



GtfOi//? 



G/TOV/? 



/>£P7Z>MZ//VG 

 G/KK//? 



Af/lSf 04SrfC//?/Z£0 /^7/P SO Af/A/OTjES y^T 



62.e°C. 



Y/./°C 



f/6o°/rJ 



^55 



76.7°C. 8Z.2°C. 87.8°C. 93.3°C. 



(/70°/rJ (?8o°/r) (/3o°/J feoovr) 



& 



Pig. 1. — The hypothetical relation of the bacterial group to raw and pasteurized milk. 



groups. The acid group is divided again into two, the acid-coagu- 

 lating, which coagulates milk within 14 days, and the acid group, 

 which merely produces acid and does not coagulate it in less time 

 than that. In raw milk the inert group is the largest. 



