SEA-FISHERIES LABORATORY 



261 



therefore, probable that after a dry season the above 

 evidences of sewage pollution would have been more 

 apparent. It was impossible to get to Bazil Point at the 

 time, but a sample of mussels from Crook Skear was 

 packed in a sterile tin, and samples of the paper on the 

 sands were put into a sterile bottle. The material so 

 rollected was examined and cultivated next morning. 



The primary cultures on neutral-red agar from six 

 of these mussels gave the following results : — 



Mussel. 



Number of "Colon-like" Colonies. 



1 



10 



2 



5 



3 



15 (also several diffuse reel patches) 



4 



6 ( ditto ditto ) 



5 



14 



6 



22 



Ten of these colonies were selected for further study 

 in pure sub-culture. Five of them were proved to have 

 been produced by B. coli. 



The paper collected was then examined. Plates jf 

 neutral-red agar were poured and small pieces of the 

 paper were taken up by sterile forceps and stroked along 

 the surface of the medium. The plates were then 

 incubated in the usual manner. The results were : — 



Plate. 



No. of "Colon-like" Colonies. 



7 (also 3 white colonies). 



14 (with many white colonies) 



Numerous and fused along the strokes. 



