Cornell University, \ 

 Ithaca, N. Y., Jan. 30, 1900. \ 



The Honorable Commissioner of Agriculture, Albany, N. Y. : 



Sir. — This bulletin is submitted for publication under Chapter 

 430 of the Laws of 1899. 



Whether or not, bacteria invade the milk channels of the normal 

 udder further than the milk duct of the teat, is a problem which 

 dairy bacteriologists liave vainly sought to answer satisfactorily. 



This bulletin contains a description of a unique method of throw- 

 ing light upon this subject togetlier with the facts determined by 

 an application of the method to the study of the udders of nineteen 

 cows. Tlie fact that milk may become contaminated by bacteria 

 before it leaves the small milk ducts of the cow's udder has a broad 

 and direct application to the methods employed in the production 

 of milk by the most progressive daii'ymen. 



The conclusions embodied in this bulletin are general in nature 

 but it is believed that future investigations will reveal more specific 

 facts concerning this hitherto unrecognized source of the contamina- 

 tion of milk. 



I. P. EGBERTS, 



Director. 



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