TIME AND TEMPERATURE 



193 



" The influence of time," Prof. Del^pine adds, " 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 teinperature is still more evident, for in every 

 category the number of good specimens is almost inversely propor- 

 tional 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 summer may also occur in winter, when the milk has 

 been hept a long time." 



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 : — 



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