MILK IRO-M COWS AVIIICII IIAAK HKEX I\ MILK 71 



duction of this bitter flavor in milk. Conn has described a 

 micrococcus which produces a bitter flavor, and Wcigmann has 

 described a bacillus which produces a similar effect. Nearly 

 all of the in\'estigators agree that the germs causing the bitter 

 flavors in milk belong to the group which acts upon the casein. 

 The bitter flavor is most ccjmmonly found in milk that has been 

 heated and then cooled to a low temperature. The heat destio}-s 

 the bacteria that produce lactic acid, but does not kill those that 

 produce the bitter flavor, owing to the fact that they are spore- 

 producing. 



The germs that produce a bitter flavor do not de\'elop in 

 milk that is parth" soured, because an acid reaction is unfavorable 

 to their growth. 



It was formerl)' thought that the organisms that cause the 

 bitter fla\'or in milk produced but}ric acid. This theory, 

 however, has been largeh" o\x'rthrown, as it has been found that 

 these germs are chiefly of the kind which peptonize the casein 

 and produce gas. 



Milk from Cows which Have Been in Milk for a Long Period.— 

 The difference in the composition of the fat }'ielded b}- cows in 

 difl'erent stages of the lactati<jn period does not seem to afl'ect 

 the qualit}- of the milk to a noticeable extent. If the C(jws have 

 Ijeen gi\'ing milk an unusually long time, the milk ma)- become 

 abnormal. 



The impurities in the small amount of milk yielded by a cow 

 almost dried up are quite apparent, ;ind the causes of the presence 

 of these impurities are readily understood. The small amount of 

 milk drawn from such a cow would contain a proportionately 

 larger amount of dirt and germs than would a larger amount of 

 milk drawn from a cow yielding more milk, providing the cleanli- 

 ness of the udder and manner of milking were the same. Cows 

 giving a good quantity of milk always seem to lm\t a cleaner 

 udder. This has been laid to the more vigorous circulation of .the 

 blood in the udder of the cow that yields a larger portion of 

 milk. 



When cows calve once a year, and have a rest of about se\en 

 weeks previous to parturition, if proper precautions are taken 



