THE RELATION OF MICROORGANISMS TO MILK. 301 



in cleaning just previous to milking. In many of the certified milk dairies 

 this source of contamination is reduced to a minimum and has little 

 effect upon the milk. 



ATMOSPHERE OF STABLE AND MILK HOUSE. Next to the cow's 

 body, the atmosphere of the stable is often the most important factor in 

 determining the bacterial content of fresh milk. In sanitary dairies this 



FIG. 75. Colonies developing from cow-hairs planted in agar plate. (Original.) 



factor is fully recognized and every effort is made to prevent the presence 

 of dust in the atmosphere at the time of milking. The atmosphere is 

 sometimes sprayed either with the hose or with steam in order to settle 

 every particle of dust at milking time. In stables where the importance 

 of this factor is not recognized and dust is allowed to exist in the atmos- 

 phere at milking time, the number of bacteria in the milk will be materi- 

 ally increased. 



