;28 CLEAN MILK 



Bitter milk may, however, be produced by other causes than the 

 growth of germs, as by certain foods which the cow may eat 

 (lupines, ragweed, wormwood, cabbages, raw Swedish turnips), or 

 as seen in milk during late lactation or in garget. In these cases the 

 milk is bitter soon after it leaves the cow, but bitterness induced by 

 the growth of germs is usually not seen except in old milk. 



Red milk may be due to contamination with blood, following 

 injury to the udder or teats. Red milk is said to occur owing to 

 cows eating large amounts of sedges, rushes, madder root, alkanet, 

 field horsetail, meadow saffron, and knot grass. 



Aside from slimy milk caused by pus escaping from inflamed 

 udders, a special germ (B. lactis viscosus) is commonly the source 

 of this condition. This germ exists chiefly in water and in dust. To 

 prevent slimy milk one must avoid contamination of the milk with 

 unboiled water or with dust. Thus all milk utensils (including 

 strainer cloths) must be thoroughly sterilized by boiling or by 

 steam in a sterilizer. 



Tanks containing water for cooling cans must be sterilized by 

 using a solution of bichromate of potash ( i ounce to the cubic foot 

 of water). Cans filled with milk may be kept in this solution, pro- 

 viding it is. not spilled into the milk. Not a drop of unboiled water 

 should be permitted to drop into milk or milk utensils. Floors of 

 rooms in which milk is kept may be disinfected by 5% sulphuric 

 -acid solution. Milk utensils must be kept inverted and covered when 

 not in use. 



Cows should not be allowed to soil their udders by wading iti 

 mud and water. Slimy milk is not harmful but very distasteful. 



This whole book is chiefly devoted to the influence of germs 

 on milk, in one way or another, and further reference to the sub- 

 ject will be found under the special topics considered. 



2. Action of Germs in Milk Upon the Consumer. — As we 

 Mve already intimated, germs do not enter milk during its forma- 



