RULES AND REASONS FOR FARM CARE OF MILK. 113 



air is pure and free from dust, and if the fore milk from each teat is re- 

 jected, the bacterial content of the milk will be greatly reduced. In a series 

 of experiments of this sort, carried out by the author, the following re- 

 sults were obtained. 



Milk received under ordinary conditions contained 15,500 bacteria 

 per c. c. 



Milk received with above precautions contained 380 per c. c. 



A repetition of the experiment under winter conditions showed 7,600 

 bacteria per c. c. in milk as ordinarily milked, and only 210 for same volume 

 where the above precautions were observed in milking. Milk taken from 

 the cow with this degree of care remained sweet over twenty-four hours 

 longer than did that which was drawn in the usual manner. 



This diminution in germ life means not only a lengthening of the time 

 during which the milk will remain sweet, but it also favors the exclusion 

 of those bacteria that are especially undesirable. The typical lactic acid 

 bacteria cannot be entirely excluded, but among those that are kept 

 out by this careful milking are the deleterious forms, those that are able 

 to cause abnormal changes in the liquid. 



ANTAGONISTIC FERMENTATIONS. It sometimes happens that the ex- 

 clusion methods fail to eradicate the persistent organism. With certain 

 abnormal fermentations, another course is still open that very often will 

 succeed where the first fails. 



Take, for instance, a milk defect where the fluid curdles in a sweet 

 condition without the production of the usual amount of acid. Such 

 a condition is not at all unusual and where present is often accompanied 

 by a taint that renders the milk undesirable for factory purposes. The 

 bacteria that are able to produce the enzymes causing the curdling of the 

 casein are unable to develop in fluids containing much acid. The lactic 

 bacteria, therefore, antagonixe this sweet curdling class, and if a starter 

 of pure sour milk from some neighboring dairy is added to the freshly drawn 

 milk, the lactic acid fermentation will gain the upper hand, the rennet 

 forming bacteria being thus suppressed by the antagonistic fermentation. 

 Such a method would not be feasible where the milk was sold for direct 

 consumption, as the addition of the lactic acid starter would hasten the 

 souring of the whole product, but where made into cheese or butter the 

 objection would not be so great, as these organisms are a necessary factor 

 in the manufacture of these dairy products, Such a method is somewhat 

 objectionable on general principles and should only be used where one 

 has failed to eradicate the difficulty by thorough cleanliness. 



CHEMICAL DISINFECTION. 



Only rarely will it be necessary to resort to more heroic measures to 

 overcome the various abnormal fermentations to which milk may be sub- 

 ject. Thorough cleanliness, intelligently applied, will usually restore con- 

 ditions to their normal state. In cases of contagious disease, more severe 



