INFECTIOUS MASTITIS 35 



likely have been of etiological importance in their respective 



cases. 



Already the facts have been pointed out, that the udder is 

 normally more or less extensively invaded with bacteria and 

 that certain species of bacteria seem to persist in the milk 

 ducts of the glands when once they become lodged there. If 

 these results apply to cows generally as rigidly as they did to 

 those examined, an explanation for the presence of a variety 

 of bacteria in the affected udders is not difficult to find. 

 Whether these particular organisms, under certain conditions, 

 would become primarily responsible for udder disease is not 

 known. The evidence suggests that a number of the bacteria, 

 heretofore described as the cause of mammitis, were in the 

 affected glands by virtue of their presence in the normal udder. 

 Concerning these points additional investigations are much 

 needed. 



The writer has examined the milk secretions from the 

 affected cows in two quite serious outbreaks of mastitis. In 

 the first, the milk was drawn in sterile bottles after the udders 

 and the hands of the milker had been thoroughly washed in a 

 I to I ooo solution of corrosive sublimate. In all, there were 

 eight samples of milk taken from as many different cows. In 

 six of the eight specimens streptococci appeared in pure cul- 

 ture. In the other two cases micrococci were associated with 

 the streptococcus. In the second outbreak, the milk from four 

 diseased udders was drawn with aseptic precautions directly 

 into tubes containing slant agar and promptly sent to the 

 laboratory, where it was carefully examined. From two cases 

 pure cultures of streptococci were obtained, while those from 

 the others were impure. The streptococci obtained from the 

 twelve cases appeared to be identical and the clinical aspect of 

 the disease in the different animals was the same. 



In a dairy that was under close observation by Ward, one 

 cow was found to be troubled in one quarter of the udder with 

 an inflammatory process which produced thickened masses in 

 the blood-stained milk. From this milk a streptococcus was 

 isolated in pure culture. It could not be differentiated from 



