SEA-FISHERIES LABORATORY. 243 



been examined, and each shellfish is analysed separately. 

 The shellfish have always been gathered from different 

 parts of the bed so that a sample representative of the 

 whole area is obtained. When collected by myself (or Mr. 

 Scott) the shellfish are pnt at once into sterilized tins with 

 tight-fitting lids and brought to the laboratory in these 

 vessels. Whenever practicable the analysis has been 

 begun on the day of collection so as to avoid changes in 

 the food contents of the fish. When this was not practi- 

 cable the tins were put into large basins and kept 

 surrounded with ice during the period pending 

 examination. 



The exterior of the shells is scrubbed under the tap 

 (Liverpool tap water is free from Bacillus coli) with a hard 

 brush and the fish are laid down on a sterile towel. 

 They are then opened one at a time with sterile knives, 

 and a cut is made through the visceral mass over the 

 region of the stomach so that the cavity of the latter is 

 opened. Sterile pipettes have previously been made by 

 drawing out pieces of glass tube, and one of these is used 

 for each animal examined. A small quantity (01 to 

 0*25 cc.) is then taken from the liquid which fills up the 

 incision in the body of the fish, and this is used for the 

 primary inoculation. This liquid is principally the food 

 contents of the stomach, but it also contains blood, and 

 the liquid which fills up the acini of the digestive gland 

 or " liver." This latter gland is very probably to be 

 regarded as an extension of the cavity of the stomach in 

 which digestion takes place, so that it also contains food 

 contents. The analysis is, therefore, that of the sub- 

 stances, partly changed by digestion, on which the 

 molluscs have been feeding at the time of capture. 



One pipetteful of this liquid is then placed on the 

 surface of " neutral-red, bile-salt, lactose agar," pre- 



