GERMS IN RELATION TO MILK n 



For 15 minutes at 70 ° C. (158 R). 



For 1 minute at yo° C. kills 99% of tubercle bacilli (tubercu- 

 losis germs) and 95-98% of other non-spore bearing germs. 



Rosenau finds milk heated to 6o° C. (149 F.) for 20 minutes, 

 kills tubercle bacilli and Malta fever germs; for 10 minutes — dys- 

 entery bacilli; for 2 minutes — typhoid, diphtheria and cholera or- 

 ganisms. 



" Ferments," or enzymes, must be distinguished from germs (or 

 living ferments), which are the most common causes of fermenta- 

 tion. Enzymes are chemical substances, but are derived from liv- 

 ing cells. 



Those related to milk are derived from three sources. 1. They 

 /may naturally exist in milk and are presumably secreted by the 

 ■udder cells, as rennet is secreted by the stomach. The ferments just 

 described belong to this class. 2. They may be produced by various 

 germs contaminating milk (as the rennet-like ferment of certain 

 germs; the liquefying ferments of liquefying or putrefactive bac- 

 teria). 3. The third class includes simply rennet obtained from the 

 animal stomach and often added artificially to milk in cheese- 

 making, etc. 



There is, indeed, as much difference in practice as in theory re- 

 garding the comparative value of heated and raw milk for infant 

 feeding — even in the case of certified milk. Thus in nine milk 

 stations (see p. 173) supplying milk for babies in different cities of 

 this country, under the best medical supervision, we find that the 

 practice of four stations is to feed the certified milk raw as it comes 

 from the dairy; in three the certified milk is wholly pasteurized; 

 and in two stations the certified milk is under some circumstances 

 pasteurized (as in hot weather). It remains to be seen whether 

 milk heated to 140 F. will be deficient in any properties of fresh, 

 unheated milk. 



Obstinate constipation is sometimes seen in animals and chil- 

 dren living on milk pasteurized at the higher temperatures. In the 



