46 MILK AND THE PUBLIC HEALTH CHAP. 



valuable paper and report, 1 illustrates this action, and the 

 influence of the temperature of incubation of the milk. 



Milk from a Healthy Cow. 

 (Immediately after milking contained 500 bacteria per c.c.) 



The duration of the period of decrease is longest the 

 colder the milk, and at 3*7 C. is very short. 



The decrease occurs not only with the bacteria usually 

 found in milk, but also with fresh milk inoculated with pure 

 cultures of pathogenic organisms. 



While there can be no doubt as to the fact of the 

 decrease of bacteria in quite fresh milk, investigators are not 

 all in agreement as to the explanation. 



According to one view the diminution of bacteria is 

 due to a definite germicidal property possessed by the milk 

 analogous to that possessed by fresh blood, although much less 

 powerful. In favour of this view is the fact that the pro- 

 perty is destroyed by heating the milk to 75-80 C., while it 

 is weakened by heating to lower temperature, e.g. half-hour at 

 56 C. Friedel, Kutscher, and Meinicke, and other investi- 

 gators, have shown that the property is in some respects 

 specific and varies with the organism. Fresh raw milk is, 

 for example, bactericidal to the cholera vibrio, but not, accord- 

 ing to these German investigators, to B. typhosus, B. coli, and 



1 Bulletin No. 41, Public Health and Marine Hospital Service, U.S.A., 

 1908, p. 449. 



