66 MILK [vi 



when it comes from the udder is devoid of it. In 

 many cases, even where the most elaborate precautions 

 have been taken by experimenters, the attempt to 

 draw sterile milk from the cow's udder has failed. 

 And yet the doctrine, that milk as originally formed 

 in the cow's udder is sterile, is a true one ; that is, 

 except when the udder is in a diseased state. The 

 failures above referred to are not to be wondered at 

 when we remember the difficulties to be contended 

 with. In the first place, we have the difficulty of 

 keeping the hands absolutely free from bacterial 

 contamination. Then the comparatively wide surface 

 of the milk brought into contact with the germ-laden 

 air in the process of milking renders the task still 

 more difficult. And lastly, assuming that such 

 difficulties are successfully overcome, we have the 

 difficulty of keeping the teats absolutely free from 

 micro -organic life. It has been found, for example, 

 that bacteria present in a drop of milk at the opening 

 of the teat may even work their way into the milk 

 cistern, and, thanks to the high temperature which 

 there prevails, may very rapidly develop. Their 

 complete removal from the udder may, consequently, 

 not be effected till milking has progressed for some 

 time. 



As illustrating this point, Lehmann has found that 

 the first 10 oz. of milk drawn contained from 50,000 

 to 100,000 per cubic centimetre (broadly speaking, 



