422 APPLIED BACTERIOLOGY 



diseases of the milk itself. Milk may, however, be no less 

 defective through disease in the cow. A large number of 

 diseases are known to be capable of being conveyed in this 

 way ; in many cases the milk itself is affected unfavourably, 

 so that it would be rejected for its unpleasant smell or 

 taste ; but this is far from being invariable. Cows suffering 

 from pulmonary tuberculosis give, for instance, an un- 

 pleasant and unsavoury milk, which carries its own con- 

 demnation with it ; those, however, which suffer from 

 generalized tuberculosis may yield a milk which only in 

 advanced stages gives the slight yellow coloration, the 

 reduction of cream, fat and milk-sugar, and the increase of 

 albumin which has been attributed to such milk. Never- 

 theless, it has been shown that cows suffering from 

 generalized tuberculosis, whether it has or has not affected 

 the udders, are capable of conveying the bacterial infection 

 into the milk, which constitutes, therefore, a serious danger. 

 Scheurlen (Arbeiten a.d.k. Ges.-Amt, vii., 1891) investi- 

 gated the extent to which milk can be freed from bacteria 

 suspended in it by the operation of a centrifugal machine ; 

 and his results, although not obtained with that object, are 

 of considerable assistance in arranging the examination of 

 milk. He found the curious result that, while of the large 

 majority of the bacteria contained in milk three-fourths 

 went into the cream on being centrifugalized, and the rest 

 stayed in the separated milk, and the same result was 

 obtained by merely leaving the milk to stand, and that 

 these results held good not only for the ordinary milk 

 bacteria, but also for anthrax, typhoid and cholera 

 organisms, the tubercle bacillus only remained to a small 

 extent in either the milk or the cream, and the large 

 majority was ejected under the centrifugal influence. 



Micro-organisms also play a useful part in connection 

 with dairy products, various organisms being employed to 



