126 MILK HYGIENE 



extent where the milk is bacteriologically clean or has 

 been sterilized according to Soxhlet's method, is one 

 of the arguments in favor of this view. Heubner is of 

 the opinion that infant mortality has been diminished in 

 this way to the extent of 27 per cent. 



In order to prevent too great contamination by such 

 bacteria it is difficult to wholly exclude them there is 

 no other way than strictly to guard the health of the 

 herds, as well as the cleanliness of the stable [of the 

 utensils and receptacles] and of the attendants. The 

 eventual danger may be partly removed by pasteurizing 

 or boiling the milk. 



VII. ADMIXTURE OF DIRT 



As has already been stated, it is customary for milk 

 to become more or less contaminated with particles of 

 dirt and their adherent bacteria during milking. The 

 dirt consists, principally, of bits of manure and, besides 

 this, hairs, dandruff, particles of food, earth and dust. 



Usually, after milking each cow, the milk is passed 

 through a strainer which retains particles of dirt ; but if 

 the strainer is not cleaned very frequently, the particles 

 of dung and dirt are softened in the milk, bacteria are 

 washed through and substances that carry abnormal 

 odors and tastes are set free in the milk. By straining, 

 then, one accomplishes only the removal of the larger 

 and more solid particles of dirt that are quite harmless 

 in themselves, such as hairs, cellulose, sand, etc. 



When unclean milk is permitted to stand, a distinct 

 sediment is formed and its presence signifies lack of 

 cleanliness in respect to production. 



The importance of dirt contamination is due chiefly 

 to the addition of bacteria with the dirt and to the solu- 

 tion of faecal matter ; the visible dirt is important only 

 as it makes the milk unappetizing. It follows that a 



