SANITARY MILK PRODUCTION 147 



teria were almost entirely yellow and white cocci. It was the opinion of 

 the authors that the average bacterial content of milk from the udders of 

 healthy cows is not over 1,000 bacteria per cubic centimeter; they figure 

 that the presence of one Dorine in a herd of 16 cows would treble the 

 bacterial count and they suggest that the removal of such a cow from a 

 herd producing certified milk might be desirable. 



Harding and Wilson studied the bacterial flora of cows' udders; their 

 discussion of the topic is based on the quantitative relationships of 1,274 

 samples representing 83 cows and on the qualitative findings from 900 

 samples representing 63 cows. They found that many forms that occur 

 in the udder are so accustomed to relatively high temperatures that they 

 do not develop well on culture media at room temperature. 



There are most bacteria in the fore-milk; in the main portion of the 

 milking there are distinctly less, while the milk of the strippings contains 

 an intermediate quantity and in fact shows numbers closely approximate 

 to the germ content of the entire flow of milk. Samples of the strippings 

 are very satisfactory for studying the udder flora. 



An examination of 1,230 samples from 78 cows averaged 428 bacteria 

 per cubic centimeter. There were about three times as many bacteria in 

 the fore as in the hind quarters; the factor controlling this distribution 

 was not found. Only about 8 per cent, of the samples examined had more 

 than 1,000 germs per cubic centimeter and the authors concluded that the 

 average germ content in the milk which could be regarded as having been 

 derived from the udder were 500 per cubic centimeter. 



Neither the age of the cow nor the period of lactation exerted any 

 decided influence upon the germ content of the milk of the udder. 



When classified according to the system of the Society of American 

 Bacteriologists the organisms found in about 900 samples fell into 71 

 groups. No organisms producing spores and no motile forms were found. 



In contrast to the experience of Harding and Wilson in isolating but 

 two streptococci from 63 cows is that of Sherman and Hastings who in 

 the milk of 88 animals in four herds demonstrated streptococci in 38.6 per 

 cent, of the samples. The animals in three of the herds were examined 

 but once, while those of the fourth herd were tested several times. These 

 authors say they are certain that if milk is to be condemned because 

 of the presence of udder streptococci a very considerable portion of milk- 

 producing animals would have to be removed from the herds. 



The fact that streptococcic infections are very common sjiould be 

 borne in mind by health officers who are investigating epidemics of septic 

 sore throat. That such epidemics may arise from streptococcic infections 

 of the udder is true but there is not necessarily any relation between 

 streptococci found in the udder and those isolated from patients having 

 the disease. Proof of their identity is demanded. 



The most illuminating study of the udder bacteria is that of Evans. 



