118 _ TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
does not help us much when we attempt to deduce the actual 
value of the fisheries as sources of food. So many are the 
sources of error and so great is our ignorance of the nutritive 
value of the products as they enter into commerce, that any 
estimate, such as that attempted by the Royal Society Food 
(War) Committee, must be of theoretical rather than of practical 
administrative interest. ven the theoretical interest of the 
estimate resides in the methods employed rather than in the 
results. 
Some Physiological Questions. 
The. Ios6 0S 9 ont aah hve fait 
First of all something must be said about the mode of 
occurrence of fat in the tissues of the herring. Various attempts 
were made to obtain good sections showing the fat am situ im 
the flesh, but all were unsuccessful. The fat itself is liquid 
at ordinary temperatures and runs away when thin slices of 
the flesh are cut out for fixation: on the other hand large 
blocks of tissue fix imperfectly. In most processes of rapid 
fixation considerable contraction of the flesh occurs, and the 
fat is thus squeezed out, and only by employing formaline was 
this avoided. Various methods were employed in order to ren- 
der the fat solid and insoluble in the reagents utilised for 
staining, but no success was obtained. Sections were cut from 
frozen tissues and from tissues embedded in celloidin and 
hardened gelatine, but whenever the staining and mounting was 
attempted the liquid oil oozed out from the connective tissue cells 
and spread over the section. Neither did teased preparations 
stained with Sudan III give good results since the oil spread 
out, bathing the muscle fibres and making a general mess. 
In the end ordinary paraffin sections were cut from formalin- 
fixed tissues and stained by Mallory’s method. It was possible 
then to see, in a general kind of way, where the fat had been. 
The Text-fig. on p. 119 represents such sections made 
