270 BACTERIOLOGICAL EXAMINATIONS 



sources of typhoid infection through the milk. The typhoid bacilli 

 are not transmitted through the bodies and udders of the animals. 



A bacteriologic examination of milk comprises a total count, 

 the presence of colon bacilli, streptococci in pus cells, tubercle 

 bacilli and special species as the case suggests. The first is done 

 as given for water, as is the second. The discovery of streptococci 

 is made by centrifugalizing a definite quantity and examining the 

 sediment for chains, particularly in relation to leucocytes, the pus 

 cells. Tubercle bacilli are found by injecting guinea pigs or by 

 dissolving the milk in antiformin (i part milk and i part 15 percent 

 antiformin) warming and examining the sediment after centrifu- 

 galization, 



