New York Agricultural Experiment Station. 113 



from the interior of the udder, as is commonly supposed, it is 

 difficult to understand why the major portion of the udder flora 

 consists of forms which cannot thrive under anaerobic conditions 

 in laboratory cultures. 



Gelatin is liquefied by 55 per ct. of the above list of germs, 

 although the action is rather slow in most cases. It is ordinarily 

 assumed that the ability to attack gelatin carries with it the 

 ability to digest casein. This latter ability is noted from the 

 appearance of tubes of inoculated milk. This method is crude 

 and unsatisfactory in cases where the action is slow. In the pres- 

 ent instance the digestion of casein was thus noted in only one- 

 half of the groups where gelatin was liquefied. There is a strong 

 probability that if sufficiently delicate tests of the action on casein 

 had been applied the numbers digesting casein and gelatin would 

 have been practically equal. The standard technique is much in 

 need of improvement at this point. The most helpful suggestion 

 for improving the technique is that of Hastings. 18 



With a large part of the udder flora provided with enzymes 

 capable of digesting casein the milk within the udder should be 

 attacked to a noticeable extent. In colostrum the changed condi- 

 tion of the milk is quite noticeable but so far as known this change 

 has not been shown to be due to bacterial action. In the milk as 

 normally drawn there is a measurable amount of water-soluble 

 nitrogen and the extent to which these water-soluble nitrogenous 

 compounds are derived from normal milk by bacterial action 

 within the udder remains to be studied. 



A considerable number of enzymes have been found in cows' 

 milk in recent years. It remains to be shown to what extent these 

 enzymes are secreted by the cow and how far they are elaborated 

 by the bacteria which chance to be dwelling within the particular 

 udder. In Bulletin 203 19 attention was called to an experimental 



18 Hastings, E. G. The action of various classes of bacteria on casein as 

 shown by milk agar plates. Cent. f. Bah: II Abt. 12:590-592. 1904. 



19 Van Slyke, L. L., Harding, II, A., and Hart, E. B. A study of enzymes 

 in cheese. N. Y. (State) Agr. Exp. Sta. Bui. 203. 1901. Also in Ann/Rpt. 

 of same Station 20 (1901) : 165-193. 1902. 



8 



