l8 MASTITIS 



value have been found associated with lesions of doubtful spe- 

 cific origin. The results of Kitt, Nocard, Mollereau, Guille- 

 beau, Zschokke, Bang and still others in which a Bacterium, a 

 Micrococcus, a Staphylococcus, and a Streptococcus have been 

 found and reported as standing in a causal relation to the 

 trouble, indicate that a variet}' of microorganisms are active in 

 producing those affections which are frequently grouped with- 

 out distinction as infectious mastitis. The review of much of 

 the literature on this subject, shows that a number of cases re- 

 ported as infectious were isolated or sporadic ones, /. <?. , they 

 were in dairies where the disease did not spread to other ani- 

 mals. While these may be truly infectious in their nature they 

 should be differentiated from the rapidly spreading phlegmons 

 which are easily recognized as infectious (contagious). 



If we take into account the variety of anatomical changes 

 which have been described in the various udder affections, we 

 can reasonably admit that different agencies may have been in- 

 strumental in their production. The various species of bacteria 

 which have been isolated from the udder lesions may very 

 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 secretions from 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 



