190 TEANS ACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Bacteriological Analyses. 



(1) Mussels from the beds near the docks (2 analyses). 



(2) Mussels from the beds at Wardley's. 



(3) Estuarine water from the channel near the docks. 



(4) Water from the channel adjacent to the Wardley's 



Ferry Slip. 



(5) Effluents from the fish oil and fish meal works. 

 Methods. 



I give an outline of the methods of analysis; 

 obviously the comparative value of such analyses 

 depends on the methods employed. Griinbaum's 

 neutral-red, bile-salt, lactose agar medium was employed 

 for the isolation of the bacteria regarded as significant 

 of faecal pollution. 



Five mussels formed a sample. The soft parts were 

 removed from the shells and cut up finely with scissors, 

 then ground up in a mortar, and made up to a volume 

 of 250 c.c. w T ith sterile water. One c.c. of this emulsion, 

 containing l/50th part of a single mussel, was then 

 plated in the agar medium mentioned ; five such plates 

 were made in each analysis. 



One c.c. of the water was similarly plated. 



In the case of the manufacturing effluents dilutions 

 were made so that 1 c.c. of each corresponded to 01, 

 001, 0001 of the original liquid. 1 c.c. of the original 

 liquid, and 1 c.c. of each diluent, were plated as in the 

 case of the water. In all cases the usual precautions to 

 obtain sterility of the apparatus and materials used were 

 taken ; and control plates to test the sterility (to the agar 

 medium employed) of the water used for dilution, the 

 air of the laboratory, and the hands of the operator, 

 were made. The results of the analyses were as follows : 



(1) Mussels from the beds near the docks. — 

 (a) Taken at low water of a neap tide : The average 



