32 Dairy Bacteriology. 



bacteria than the whole milk, does not coagulate nearly as 

 soon. In a series of five trials the fore milk did not curdle 

 at room temperature on an average until after 84 hours, 

 while the average time of curdling of the whole milk was 

 38 hours. 



Not all species of bacteria seem to be able to maintain 

 themselves in the udder even if they are introduced therein. 

 Dinwiddie 1 injected into the milk cistern a facultative an- 

 aerobic lactic acid-producing form that grew at 99 F. 

 Several subsequent examinations failed to reveal the or- 

 ganism in any case. Ward 2 experimented with B. prodigi- 

 osus which he introduced through the milk duct. He was 

 able to determine its presence six days later. Experiments 

 have also been made with B. coli communis, B. cloacae and 

 B. lactis aerogenes? all of which are gas-generating species, 

 but in no case did these forms thrive. 



In securing milk under conditions whereby the bacterial 

 content is reduced as much as possible, it is advisable to 

 throw out these first few streams. In doing so, the in- 

 trinsic loss is practically negligible, for the amount of 

 butter fat in even the first pint of a milking is only about 

 0.7, 4 or one fifth of the normal. 



Infection directly from animal. It is a popular belief 

 that much of the germ life that is found in milk is derived 

 from the food that is consumed by the animal, but such a 

 condition cannot prevail in the healthy animal for the 

 reason that bacteria in and on fodder are not absorbed into 

 the tissues proper, or if they are, they are quickly killed 

 by the germicidal properties of the body fluids. The 



Dinwiddie, Bull. 45, Ark. Expt. Stat., p. 57. 

 'Ward, Journ. of Appld. Mic., 1898, 1:305. 

 Appel, Milch Zeit., 1900, No. 17. 

 Snyder, Chemistry of Dairying, p. 10. 



