216 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



THE FAT-CONTENT OF IRISH SEA HERRING. 

 By Jas. Johnstone, D.Sc. 



Throughout the period when biometric investigations on 

 Irish Sea herrings were made by Mr. W. Riddell, fat-analyses 

 of the muscle substance of the fish were also made. Samples 

 of herring from the summer fishery near the south end of Isle 

 of Man, from the winter fishery in Carnarvon and Cardigan 

 Bays, and from the sprat fisheries in Morecambe Bay, and in 

 the Estuary of the Mersey have been examined. Several 

 interesting points suggesting further investigation have arisen 

 in connection with this research, but so far time has not been 

 available for their proper treatment. I hope, however, to 

 return to this subject when the summer fishery of 1915 begins. 

 The investigation may be of some importance in relation to 

 methods of food preservation, a subject which indeed suggested 

 it in the first instance. 



The analyses were made by means of the ordinary Soxhlet 

 apparatus, using carbon tetrachloride as a solvent instead of 

 ether. The extreme oiliness of some of the fish made the 

 sampling a matter demanding some care. The muscle 

 substance could not easily be chopped up, because much oil 

 would have been lost in the process. The herring to be 

 sampled was, therefore, lightly scrubbed with a test-tube 

 brush so as to remove the scales. The skin was then dried 

 with a towel, and, by means of a sharp razor, a series of cuts 

 were made through the flesh as close together as possible. 

 A tangential cut was then made so as to free these thin sections 

 of muscle substance, which were then lifted by clean forceps 

 and put into a paper thimble contained in a weighing bottle. 

 Both thimble and bottle had previously been dried in the 

 water oven and weighed. The whole was then weighed and 

 the weight of the sample of muscle substance obtained by 



