SOURCES OF CONTAMINATION. 



17 



TABLE 2. Results of the bacteriological examination of hard clams (quahaugs) in the shell. 

 COLLECTED FROM GROUNDS WHERE INSPECTION SHOWED NO SERIOUS POLLUTION. 



COLLECTED FROM GROUNDS SHOWING VERY SERIOUS POLLUTION UPON 



INSPECTION. 



Clams appear to contain a larger number of bacteria in their liquor 

 and body contents than do oysters. This may be explained in part 

 by the fact that the clams in the latter table were collected from 

 localities where extreme pollution was indicated. Each sample gen- 

 erally represented at least five clams, which constituted a composite 

 sample. In a few instances only one or two large clams were obtained 

 from a given locality for examination. 



TABLE 3. Results of the bacteriological examination of sea water over oyster beds. 



COLLECTED FROM LOCALITIES WHERE INSPECTION SHOWED NO SERIOUS 



POLLUTION. 



72743 Bull. 13611- 



