136 MILK BACTERIA AND HEALTH. 



unexplained reasons, the lactic bacteria do not overcome 

 the putrefactive organisms, and the latter continue to 

 develop for many hours, until the milk is finally filled with 

 them in large quantities. Such milk .will remain without 

 souring for a longer time than usual, but evidently is more 

 dangerous than ordinary milk which has soured. The pres- 

 ence of such large numbers of putrefying bacteria cannot 

 fail to make such milk unwholesome. It is evident, of 

 course, that such milk would be used freely, and it is cer- 

 tainly possible that a part of the digestive disturbances 

 attributable to milk are due to the milk having become filled 

 with organisms of putrefaction instead of the more harmless 

 lactic bacteria. 



The practical question how the milk can be guarded 

 against such organisms and, therefore, against the likelihood 

 of producing these diseases is difficult to answer. There 

 are two methods that may be adopted. The first is by guard- 

 ing the source of the milk, and consequently reducing the 

 number of bacteria. The adoption of the various devices 

 for preventing contamination of milk, pointed out on a pre- 

 vious page, is the only method that can be suggested for 

 preventing the milk from becoming contaminated .with such 

 organisms. The alleged cause of summer complaint comes 

 from some external source, possibly from water. The putre- 

 fying bacteria come mostly from sources external to the cow, 

 and the greater the cleanliness in the dairy the less will be 

 the chance that the milk will be filled with these unwhole- 

 some bacteria. The second method is to adopt sterilization 

 or pasteurization. If pasteurizing or sterilizing can be applied 

 to the milk at an early stage, the bacteria may be destroyed 

 and thus the subsequent development of their toxic products 

 can be checked. This method materially reduces the num- 

 ber of bacteria and, therefore, reduces the danger of the 

 development of intestinal disturbances. 



