THE RELATION OF MICROORGANISMS TO MILK. 



Bacteria in Different Quarters of Cow's Udder. 



299 



The number of organisms normally found in the udder is much 

 smaller than would be expected when we consider the fact that ideal 

 conditions of food and temperature are provided in the udder. The 

 relatively small number of organisms is perhaps due to some germicidal 

 action existing in the udder. Attempts to increase the germ content in 

 the udder by injecting cultures of different species of saprophytic bacteria 

 have failed to produce a continued increase, the injected organisms usually 

 decreasing very rapidly in numbers until they disappear at the end of a 

 few days. From the standpoint of ordinary market milk, the number of 

 bacteria found in the healthy udder is so small that it is of little com- 

 mercial importance. In dairies where a very small germ content is 

 desired, however, this source of infection must be taken into account and 

 in certain cases individual cows, which normally have a high bacteria 

 content in the udder, can be discarded to advantage. 



It is evident that many species do not find the conditions in the udder 

 suitable for their growth, since investigations have shown that compara- 

 tively few species exist for any length of time in the healthy udder. Cer- 

 tain types of cocci are the predominating forms with occasional cultures 

 of other species. The Bad. lactis acidi type does not thrive in the udder. 

 The types of organisms commonly found there do not seem to develop 

 rapidly in the milk when it is held at low temperatures and fail to 

 produce any appreciable changes in it. 



Diseased Udders. If, however, the cow is suffering from tuberculosis 

 in the udder, the bacterial condition may be quite different from that 

 described above. In this case, the milk may be filled with the tubercle 

 bacteria before it leaves the udder. In cases of inflammatory trouble in 

 the udder the milk may contain very large numbers of organisms, fre- 

 quently many millions per c.c. at the time the milk is drawn. 



