CHAPTER II. 

 'SOURCE OF BACTERIA IN MILK. 



MILK. FROM HEALTHY UDDERS. 



AT the moment it is secreted by the healthy udder milk 

 is absolutely free from bacteria. This, though certainly 

 true, has been difficult to prove. Thirty years ago Lister 

 and Hall, pioneers in dairy bacteriology, endeavored to de- 

 termine whether milk could not be drawn from the cow in 

 such a way that it would contain no bacteria. Their experi- 

 ments, consisting of drawing milk into sterilized vessels 

 under special precautions, were successful in a sufficient 

 number of cases to demonstrate to their satisfaction that the 

 pure, freshly secreted milk contains none of these organisms. 

 In more recent years, however, such experiments are rarely 

 successful in spite erf the very greatest precautions that are 

 taken. With all of- our improvements in aseptic methods it 

 is a practical impossibility to draw any considerable quantity 

 of milk from a cow in such a way that it contains no bac- 

 teria. It is, however, occasionally done, provided care is 

 taken to collect milk at the end of the milking only, and to 

 collect small samples. But though thus occasionally possi- 

 ble no methods can be adopted which result in uniformly 

 obtaining such milk, and it is quite impossible for the dairy 

 man to draw milk from the cow in such a manner that it is 

 free from bacteria. That the milk while in the glands is 

 free from bacteria is indicated by other methods of work 

 The udder has been examined by bacteriological methods 

 directly after the slaughter of the animal, and while in some 

 cases bacteria are found in various parts of the gland, in 

 other cases, if the precautions taken are sufficient and 



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