172 CONTROL OF THE MILK-SUPPLY. 



and consequently the drinking of such milk is far worse than drinking 

 fresh milk which is, most likely, supplied chiefly with lactic bacteria. 

 Sterilized milk, if it does retain a single spore, will be in time, more 

 dangerous than ordinary fresh milk. For this reason, among 

 others, this practice of treating milk to superheated steam for the 

 purpose of absolute sterilization has disappeared. 



The term sterilization is sometimes applied to the simple boiling 

 of milk. This was recommended by physicians long before its 

 real significance was understood and has been very widely used in all 

 civilized countries. Its ease of application explains the reason for 

 its popularity. It is only necessary to place the milk upon the 

 stove and allow it to come to a boil, and the end is reached. In 

 some countries very little milk is used without such previous boiling, 

 and even the children are taught in school that it is dangerous to 

 drink milk without such treatment. The purpose aimed at in this 

 wide use of boiling, which is commonly, though not properly, 

 called "sterilization," is simply to destroy the danger of distributing 

 diseases by the destruction of pathogenic bacteria. This purpose 

 is certainly achieved, for the boiling temperature does destroy all the 

 pathogenic bacteria which are likely to be in milk, since none of 

 these are spore producers. 



But several practical objections have arisen: 



1. The bacteria spores are not destroyed, and such milk, if kept, 

 will surely undergo a fermentation. But this is of little importance 

 if the boiled milk is to be used at once. 



2. The milk acquires the well-known taste of boiled milk which 

 is, to most people, unpleasant. People are willing to take boiled 

 milk upon an emergency as an ivalid diet, but few will continue its 

 use. The taste is not enjoyed, and, rather than drink boiled milk, 

 the majority of people will give up drinking milk altogether. This 

 is certainly not desirable, since milk forms one of the best and 

 cheapest foods. Any treatment which greatly reduces the amount 

 used is, in itself, undesirable; and the practice of boiling milk 

 certainly does reduce the amount used. 



3. Milk treated to a temperature as high as boiling becomes 

 somewhat less easy of digestion and assimilation. The heat pro- 



