No. 6. DEPARTMENT OF AGRICULTURE. B69 



(4.) Les8 Gomiiiuu Foiins ol Feimentation in Milk. — The kinds of 

 bacteria described above are found commonly occurring in milk, 

 but there are others which appear only occasionally, and some of 

 these will now be briefly considered. 



Most dairymen sometimes have milk that fails to sour or curdle, 

 but after a few hours begins to be slimy and finally can be drawn 

 out in long threads. This condition more commonly appears in 

 cream. The trouble may be due to diseased udder, in which case 

 it is apparent at once when the milk is drawn. The form which 

 does not appear at once after milking is due to bacteria. Other 

 abnormal forms of fermentation in milk result in producing alcohol, 

 bitter milk, soapy flavor, fishy flavor, red, blue and other colors. 



(5.) Disease Germs in Milk. — Milk furnishes a medium in which 

 many disease germs can readily develop. Some disease-producing 

 bacteria are capable of being transmitted directly from a diseased 

 cow to a human being through the milk. It is quite generally be- 

 lieved that if milk is taken from a cow suffering with tuberculosis 

 in the udder, it will be fairly sure to contain tuberculosis germs; 

 and such milk taken into a human body may produce tuberculosis. 

 Other disease-producing bacteria may get into the milk after it is 

 drawn, having nothing whatever to do with the cow. Such are 

 germs causing typhoid fever, scarlet fever, diphtheria and diarrhoeal 

 diseases, such as cholera infantum. Such disease germs may get 

 into milk from a case of illness on the premises where the cows are 

 milked, through the carelessness and ignorance of the members 

 of the household. 



CHAPTER III. 



PREPARATION OF MILK FOR MARKET. 



In the preceding chapter we have seen that bacteria of different 

 kinds get into the milk in various ways and, under conditions favor- 

 able to their activity, cause fermentations that may result in rend- 

 ering milk totally unfit for sale. Therefore, the chief aim to be 

 kept in mind in preparing milk directly for market is practically 

 this, how to keep under control the growth of bacteria to such an 

 extent that injurious fermentations shall not take place to any 

 marked degree. Three general methods are in use for securing con- 

 trol of fermentations in milk: (1) Keeping bacteria from getting 

 into milk, (2) preventing growth of bacteria already in milk, and (3) 

 destroying bacteria already in milk. We will now consider these 

 methods separately. 



