46 Agricultural Bacteriology. 



coDtamination rather than a means of removing the 

 bacteria. The filtering of milk as a method of removal 

 of bacteria can never be a success since anything that 

 would remove the bacteria would also remove the fat 

 globules as these are larger than the bacteria. 



Clarifying of milk. When milk is passed through a 

 cream separator, a slimy mass collects on the wall of 

 the bowl. This material is very high in bacteria. It 

 was urged for many years that the clarifying of the 

 milk was a successful means of removing the bacteria. 

 Although the bacterial content of the slime is very 

 much higher than that of the milk separated, the re- 

 daction of the germ content of the milk and cream is 

 insignificant, because the amount of slime removed is 

 such a small part of the milk separated. The clarifica- 

 tion has no effect on the keeping qualities of the milk. 

 The clarification removes more efficiently than strain- 

 ing the insoluble dirt in the milk. Clarified milk 

 shows no sediment on standing and for this reason the 

 process has been adopted by many milk-companies. 

 Like straining, it makes the milk appear better than it 

 really is and thus misleads the consumer. 



It is evident f ronb what has been said that but little 

 can be done in removing the bacteria from milk when 

 once they have gained access. The more successful 

 way to preserve the milk is to prevent the growth of 

 the bacteria. This can be done in a number of ways: 

 (1) by the use of low temperatures, (2) by the use of 

 certain chemicals, which have an antiseptic action, i. e. 

 prevent or retard the growth. 



Cooling of milk. The use of low temperatures is the 

 tlie most widely used and the most efficient means of 



