BACTERIA IN MILK. 221 



germs without haying its physical or chemical nature notice- 

 ably changed. Such milk, when cooled, cannot be distin- 

 guished from fresh milk. It must be stated that the efficiency 

 of such a moderate temperature in rendering harmless the 

 tuberculosis bacillus is not fully admitted by all observers. 



This conclusion is of immense value and this method is of 

 great practical utility. The value of pasteurization is becom- 

 ing rapidly recognized and this method of treatment is becom- 

 ing widely adopted. The advantages of pasteurization lie in 

 the following facts : 



1. It produces milk which cannot be distinguished from 

 fresh milk and will be used as freely. 



2. It increases the keeping property of the milk, but not to 

 the extent of leading the consumer to believe he can keep it 

 indefinitely. The consumer is thus forced to use it up before 

 the spore-bearing bacteria get an opportunity of multiplying 

 sufficiently to produce the injurious secretions which occasion- 

 ally render sterilized milk dangerous. The very fact that the 

 method does not destroy all bacteria is a safeguard. 



3. It removes the danger of distributing pathogenic bacteria. 

 This is certainly true of the typical diseases mentioned. 

 Whether it similarly removes the danger of diarrhceal dis- 

 eases, not dependent upon any known specific bacteria, is not 

 yet positively known by experiment, inasmuch as we do not 

 know the actual cause of the diseases. But the practical ex- 

 perience of physicians tells us that pasteurized milk acts as effi- 

 ciently as sterilized milk in reducing these diseases. 



4. This method of treatment is perfectly applicable upon a 

 large scale. Already pasteurization has been adopted in some 

 places by large dairy companies whose milk is distributed 

 around cities, and the plan is becoming more popular each 

 year. At the present time there promises to be, in the near 

 future, an extensive adoption of this treatment into at least a 

 part of the milk supply of large communities. Pasteurizing 

 machines which can treat a thousand quarts at once are easily 



