SEA-FISIIERIES LABORATORY. 191 



iiiniiber of iiitestiuul bacteria coutaiiied in one mussel 

 was (ib. {h) Taken at low water of a spring tide: The 

 average number of intestinal bacteria contained in one 

 mussel was 90. 



(2) Mussels raked from the channel near Wardley's 

 Ferry Slip : The average number of intestinal bacteria 

 contained in one mussel was 150. 



(3) Estuarine water from the channel adjacent to 

 the place where samples (1) and (2) were taken : 1 c.c. 

 of the water contained, on the average, OT bacteria 

 (less than one organism per 1 c.c). 



(4) Water from the channel adjacent to the 

 Wardley's Ferry Slip : 1 c.c. contained, on the average, 

 22 intestinal bacteria. 



Those unfamiliar with the bacteriology of shell-fish 

 and sewage effluents may best appreciate the meaning 

 of these results from the following comparisons. As a 

 standard result which may enable us to assign a value 

 to the Wyre analytical figures we may take the case of 

 the Estuary of the Conway River in North Wales, 

 where the sources of sewage contamination are abundant 

 and obvious ; and where there is actual epidemiological 

 evidence of the transmission of enteric fever by the 

 mussels taken from the estuary. Mussels taken from 

 these beds contained, on the average, about 2,000 

 intestinal bacteria each, the analysis being made by 

 methods identical with those described above.* 



* Mussels bought from a retail shop may be very much worse 

 than those taken froin a badly polluted Estuarine area. In one 

 sample bought from a low-class Liverpool fish-shop I found — as the 

 average of ten mussels — that each shell-fish contained 17,150 

 intestinal bacteria. It must often be the case that multiplication of 

 the contained bacteria — perhaps even direct re-infection — may take 

 place during storage in insanitary premises ; and obviously it would 

 be unfair to lay the blanie of such excessive pollution on the natural 

 conditions of the beds from which the shell-fish were collected. 



