356 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



of gathering from the mussel beds and that of consump- 

 tion would have to be excluded. It is well known that 

 mussels are sometimes kept by the dealers for a consider- 

 able time before being sold. Thus an enquiry into a case 

 of ptomaine poisoning in Liverpool some years ago showed 

 that an interval of seven days had elapsed between the 

 dates of gathering and collection, and nine days between 

 gathering and the death of the person consuming the 

 mussels. In the course of a period of this duration, or 

 even of less, the possibility of contamination of mussels, 

 from sources other than the natural habitat of the shell- 

 fish, must be a very real one. Such extraneous contamina- 

 tion is all the more possible when the mussels are stocked 

 by the lower class of dealers. 



It may reasonably be urged, however, that the amount 

 of pollution of the Conway mussels is such as to make it 

 most desirable that some measures should be taken to 

 reduce the contamination of the River Conway — and, 

 consequently, of the mussels there — as far as is possible. 

 It will be seen that seven sewers open into the river within a 

 very limited area, and these do not represent all the 

 contributing sources of pollution. In the construction of 

 the existing Conway sewerage systems, as in that of many 

 other sea-side towns, the nearest and most convenient 

 point of discharge into tidal waters has been chosen, 

 without much regard to the possibility of fouling either 

 shellfish beds or foreshore. At Conway the sewage is 

 crude, it flows continuously into the river and in some 

 cases spreads itself over sand or mud flats, producing 

 some contamination of these. Without venturing to 

 express an opinion on points of sanitary engineering, I 

 think it might be quite practicable to take steps which 

 would do away with much of the evil effects of the present 

 sewerage system. The Conway mussel industry is one of 



