SEA-FISHERIES LABORATORY. 329 



number of empty shells present on the .ground at the time. 

 We looked for paper or other naked-eye evidence of 

 sewage deposits on the bed but could see little traces of 

 such matter. 



This bed has long had an evil reputation and I am 

 informed by Dr. F. Booth, Medical Officer of Health for 

 the Urban District of St. Annes, that though he has no 

 direct evidence of illness in St. Annes resulting from the 

 consumption of these mussels, the Medical Officer of 

 Blackpool has attributed several cases of enteric fever 

 directly to the consumption of mussels from this bed. 

 Unfortunately there is also grave reason for suspecting 

 the cockles from the adjacent foreshore. It is apparently 

 the case that cockles clean themselves of ingested sewage 

 bacilli much less readily than mussels (Klein). That is, 

 these micro-organisms find a more suitable nidus in the 

 tissues of the cockle than in those of the mussel. 



I think the direction of the tidal streams favours the 

 contamination of these mussels. Not only is there direct 

 and continual pollution by the St. Annes sewer, but a 

 considerable quantity of greatly diluted sewage from 

 Lytham and even from the Kibble Estuary generally, 

 must find its way over these grounds at the earlier period 

 of the ebb-tide. It is true that St. Annes sewage must 

 pass out to sea through the North channel after the 

 higher sand banks have become bared by the ebb, but it 

 is also probable that, with the first of the flood some at 

 least of this sewage may find its way back through the 

 same channel on to the mussel bed. The topography of 

 the coast, indeed, renders it impossible that these shell- 

 fish can escape direct contamination. 



The sample of mussels for examination was collected 

 about 5 p.m. on 6th June. The mussels were collected 

 from every part of the bed and at once placed in a recently 



