SEA-FISHERTES LABORATORY. 203 
PeovbmtOLOGICAL INVESTIGATIONS IN 
RELATION TO SHELL-FISH POLLUTION. 
By JAS. JOIINSTONE. 
I.—THE LANCASHIRE AND CHESHIRE COCKLE GROUNDS. 
Il.—THE MUSSEL BEDS ON PIEL SHORE. 
IlJ.—EXPERIMENTS ON THE PURIFICATION OF POLLUTED 
MUSSELS. 
I. Late in 1907 Dr. Jenkins suggested to me the 
advisability of examiing the condition of the cockle beds 
on the Lancashire littoral; and during the last three 
months of that year, and the first three of 1908, various 
inspections and analyses were made. Dr. Jenkins and I 
visited Formby on 18th October, Flookburgh on 18th 
November, Ansdell on 25th November, Leasowe on 2nd 
December, and Silverdale on 1I1th December, 1907. On 
each occasion we examined the cockle-bearimg sands for 
evidences of sewage pollution, and I collected samples of 
the shell-fish, and, in some cases, of the water on the 
sands, for bacteriological analysis. 
Methods of analysis in the case of a cockle differ im 
detail from those employed for mussels and oysters. In 
the latter case it is generally useful to examine each 
molluse individually, by taking a sample quantity of the 
contents of the stomach and intestine; and in this way 
one can ascertain the variations in lability to pollution 
of the shell-fish on different spots of the scar examined. 
This is, however, difficult in the case of the cockle, and 
the method employed was essentially that recommended 
by Dr. A. C. Houston. 
About 50 cockles, collected from different parts of the 
bed in question, formed a sample. ‘The shell-fish were 
