SEA-FISHERIES LABORATORY. 107 
as to bring about a considerable loss of nitrogenous material, 
gelatine and watery extracts. 
By far the greatest effect (from the point of view of the 
public food supply) is that produced in fresh herrings by the 
ordinary method of cooking—that is, frying. No doubt the very 
_ high energy-values for these Manx herrings are largely unavail- 
able values, for large quantites of oil must be lost in the cooking 
process. It appears that there is only one way in which these 
large fat-contents may become actually available as food, that is, 
by cooking or preparing the fish in such a way as to“ fix ” the 
oil in the flesh. The well-known process of“ potting”’ (Lancs.) 
fresh herrings by cooking in simmering vinegar does seem to 
fix the fat. There is little or no escape of oil into the liquid 
in the cooking vessel, and the flesh of the fish has a firm con- 
sistency and appearance which suggests actual solidification 
of the oil. The only tentative experiments which I have made 
(obviously the ordinary Laboratory is badly equipped for this 
work) seem to suggest that this retention, in an assimilable 
and easily digestible form, of the oil is actually obtained by the 
cooking in hot vinegar. 
Of course, fat “ mordants ” are known in histological work. 
Acetic acid and potassium bichromate are used to fix fat droplets 
in tissues and prevent their solution in the processes of pre- 
paring sections. Of course such powerful reagents can hardly 
be employed in cooking operations, nor is it desirable that the 
oil should be rendered insoluble, but on the other hand, ‘‘ mar- 
inaded”’ herrings and other Clupeoid fishes have long been 
known and in these processes of conservation there is probably 
fixation of fat. Then there are the sardining processes in which 
preliminary slight salting and drying are apparently essential 
steps, and there are of course the processes of conservation in 
various sauces and even in white wine. 
The fact seems to be that a full utilisation of the Clupeoid 
fish supply of the United Kingdom seems to be possible only 
by employment of some conserving methods. 
