y 
2 
a 
SEA-FISHERIES LABORATORY. 87 
that further investigation is unnecessary, and there is hardly 
anything of the same kind* in the literature with regard to the 
herrmg. Yet the seasonal changes that occur in the tissues 
oi the latter fish are far more interesting and the economic 
value of investigation is vastly more evident. 
This purely physiological research has not, of course, been 
attempted here. Obviously it would have been foolish to 
attempt it without considering also the food of the herring. 
Very interesting questions are suggested here: for instance, 
the origin of the oil that is so characteristic of marine Copepods 
and Schizopods from thew food (Peridinians and Diatoms) ; 
the chemical nature of this oil and its relation with the oil of 
the herring ; and the fate of the peculiar hpochromes that are 
present in the oil of the micro-crustacea. 
Under present conditions the mvestigation of the latter 
questions is impossible, for plankton catches containing Diatoms, 
Peridinians, Copepods, &c., cannot be obtained in quantities 
large enough for analysis. And the amount of routme work 
that would be involved in an adequate study of the seasonal 
metabolism of the herring is so great that it could only be at- 
tempted by collaborators. 
Therefore this report is to be regarded only as a general 
survey of the dietetic question—the food value of the English 
West Coast Herring. 
Methods. 
These very technical details are necessary for criticism of 
the results set forth. | 
Sampling. 
Fortnightly samples were received from Mr. T. N. Cregeen, 
of the Port Erin Biological Station, Isle of Man, during the 
months May to September of the years 1914, 1916 and 1917. 
* With the exception of Milroy's study of seasonal changes. Rept. Fishy. 
Bd. for Scotland, Pt. L11, 24th Ann. Rept. and Pt. LI, 25th Ann, Rept. 
