112 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



ON THE DIETETIC VALUES OF HERRINGS AND 

 OTHER FISHES. 



By Jas. Johnstone, D.Sc. 



The results of a few analyses which were made during 

 1919 as part of some advisory work carried on for the Cannery 

 Committee of the Board of Agriculture and Fisheries may be 

 recorded here. 



Manx Summer Herrings. 



As in previous years a good deal of attention was directed 

 to this interesting fishery and samples of the herrings caught 

 were received fortnightly from the Port Erin Biological Station. 

 The first sample was taken about 23rd April, 1919, and the 

 last one about 18th September. At the beginning of the 

 season the fish were all immature, being in Hjort's Stage I ; 

 but by September 18th, about which time the fishery was 

 discontinued, the herrings were spawning, and of the last 

 sample of 12 fish four were spent. The maturation of the 

 ovaries and testes was a fairly rapid process occurring mostly 

 during August and September. 



The methods of analysis were similar to those described in 

 former reports. In all cases " proteid " is nitrogen x 6.25, and 

 the apparently large errors of the analyses are traceable to 

 the use of the particular factor 6.25, as may be seen by looking 

 at the columns in the tables with the headings " N." These 

 give the percentage of nitrogen in the dried extracted residues 

 after deductions are made for the variable amount of " ash," 

 which in the case of the canned products is mostly added salt. 

 The samples taken for analysis were, in all cases, composite 

 ones, small portions of the muscle substance from different 

 parts of each of the fish in the sample being added together to 

 form the material which was dried and extracted. 



