138 



THE BACTERIAL CONTENT OF MILK 



Unmixed milks kept for various lengths of time, but collected 

 from the udder in sterilised vessels (tuberculous sample excluded), 

 also yielded a like result : — 



" The influence of time is well shown by the number of specimens 

 remaining good, even at a high temperature, when the milk had 

 been kept only half a day. On the other hand, the influence of 

 temperature is still more evident, for in every category the number 

 of good specimens is almost inversely proportional to the height of 

 the temperature. Still, it is important to keep the two factors of 

 time and temperature in mind. What is produced in a few hours 

 in sufnmer may also occur in winter, when the milk has been kept a 

 long time " (Del^pine). 



The converse is also true, namely, that if the temperature of 

 milk be reduced by refrigeration the toxicity of the milk is lessened. 

 Professor Delepine has shown that the mortality from all causes in 

 guinea-pigs inoculated with refrigerated milk is considerably less 

 than it is if unrefrigerated milk be inoculated : — 



