20 



Dairy Bacteriology. 



The same is true after it is milked. From the time of milk- 

 ing, until it is consumed in one form or another, it is con- 

 tinually subject to contamination from external sources. 

 In the main, germ life gains access while the milk is on the 

 farm, but even in the factory, the opportunities for infec- 

 tion are present in 

 greater or lesser de- 

 gree. Those forms 

 that become estab- 

 lished early generally 

 predominate in the 

 milk, as their intro- 

 duction enables them 

 to develop for a longer ^ 



period of time. It f 

 must be remembered 

 that by far the greater Sb& 

 part of these organisms 

 are relatively harmless. 

 While they are not 

 concerned in the production of disease, the larger majority 

 of them do affect, more or less seriously, the quality of 

 the milk. They are, therefore, undesirable from the milk 

 vendor's point of view, although in the processes of butter 

 and theese-making, the presence of some kinds is very de- 

 sirable. 



Under the varying conditions in which milk is handled 

 it must of necessity be infected with bacteria of different 

 sorts, yet normally the type of fermentation that occurs is 

 quite the same, showing that certain species find milk such 

 a favorable nutrient medium that they soon gain the ascend- 

 ency over other forms. 



Fio. 5. Microscopic appearance of milk show- 

 ing relative size of fat globules and bacteria. 



