SEA-FISHERIES LABORATORY. 



331 



Mussel. 



No. of Colon-like Colonies. 



White 

 Colonies. 



1 



170 



12 



2 



80 



4 



3 



36 



7 



4 



with 2 diffuse red patches 

 15 



1 



5 



with numerous red patches 

 76 



1 



6 



with many diffuse red patches 

 132 



3 



7 



with several diffuse red patches 

 28 





8 



39 



numerous 



9 



with several diffuse red patches 

 32 





10 



with numerous diffuse red patches 

 about 320 











The significance of these results is that unpolluted 

 mussels or oysters taken far out at sea contain no bacteria 

 in their stomachs which grow on neutral-red agar. 



'This is also true of non-sterile but uncontaminated 

 sea water. The great majority of the organisms growing 

 on this medium are such as are found in sewage, and 

 indeed are those that have their normal habitat in the 

 human intestine. 



The diffuse patches are formed by the fusion of 

 numerous " colon-like " colonies. 



