THE INVASION OF THE UDDER BY BACTERIA. 



BY ARCHIBALD R. WARD. 



The designation of the sources from whicli bacteria gain access to 

 milk is one of the important results of the application of bacteriology 

 to the amelioration of the dairy industry. Among dairy bac- 

 teriologists there is a marked unanimity of opinion concerning the 

 presence of micro-organisms in unclean utensils, the dust in the air 

 of stables and in the lirst milk drawn from the teats at each milkiiig. 

 The necessity for the application of precautions to prevent tlie con- 

 tamination of milk from those sources is well recognized and is 

 exliaustively discussed in the more recent dairy literature.* 



Concerning the place at which milk first becomes contaminated 

 with bacteria is a controverted matter among bacteriologists at the 

 present time. The more generally accepted views are expressed in 

 the following quotations. Grotenfelt f says that " When the milk 

 is first drawn from the udder of a healthy cow it is germ free or 

 sterile. The original sterility of normal milk is due to the fact that 

 the bacteria can not gain access to the milk glands from without as 

 long as the udder is not injured in any way." The translator of 

 Grotenfelt's work adds in a footnote this statement made by 

 Lehmann ;{ : " The bacteria in the milk cisterns will be largely 

 washed out by the first milk drawn, but not all removed until milk- 

 ing has progressed some time." 



V. Freudenreich § holds a somewhat similar view. In his dairy 

 bacteriology the following is found : " In the udder, milk is germ 



*H. L. Russell, Dairy Bacteriology. Ed. v. Freudenreich, Dairy Bacteriology, 

 translated by J. R. A. Davis. R. A. Pearson, Farmers' Bulletin No. 63, U. S. 

 Department of Agriculture. 



f Gosta Grotenfelt, The Principles of Modern Dairy Practice, translated by F. 

 W. Woll, p. 23. 



:}: Lehmann, 17te Versammlung d. deut. Ver. f. offent. Gesundheitspflege. 



§ Dr. Ed. V. Freudenreich, Die Bakteriologie in der Milchwirthschaft, 2d 



edition, p. 25. 



281 



