UDDER. 3 



genie power, should be noted. Experiments with forms 

 undoubtedly habituated to conditions within the udder have 

 been made in very few instances and further work along this 

 line is desirable. The observed persistence of certain bacteria 

 in certain particular quarters of the cow's udder from day to 

 day is of significance (26, 66). The presence of bacteria in 

 the udder is paralleled by the case of other mucous membranes. 

 These facts render it unnecessary to look to hematogenous 

 infection as the immediate source of the bacteria in the milk, 

 even though bacteria have been demonstrated in other normal 

 organs like : the spleen (21). Such an explanation of the 

 source of the bacteria would hardly account for the difference 

 of the bacterial flora of different quarters of the udder. No 

 evidence has been brought forward to substantiate the notion 

 that the bacterial content of milk is influenced by bacteria in 

 feed or water transferred via intestines, blood, and udder. 

 Conclusions contradicting this view have been drawn from 

 observations which have shown that the common bacterial flora 

 of the udder is quite different from that of the intestines (26). 

 Experiments have been made by feeding certain micro-organ- 

 isms to cows and then searching for the same organisms in the 

 milk, without success. The results might have been otherwise 

 if care had not been taken to prevent contamination from the 

 feees. One writer used B '. prodigiosus (66), while another (26) 

 used the same organism in one trial, and at another time used 

 distillers' grains containing yeasts, oidium, proteuS, bacilli., 

 and streptococci. The bacterial content of milk drawn under 

 aseptic precautions has been determined in .cows fed on hay 

 and on grass, and no difference was found in the numbers 

 present in the milk (26) . The' bacteria in feed and water may 

 modify the bacterial co'ntent of the milk, but by other channels 

 than through the interior of the udder. 



Character of bacteria. The Organisms most frequently found 

 are micrococci, in general capable of producing visible changes 

 in milk rather tardily (67), and hence they do not interfere with 

 its apparent keeping quality. Conn, Esten and Stocking (ll) 

 have pointed out that one of these udder organisms {Micro- 

 coccus lactis varians} is the most common and widely distributed 



