128 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
that is, to the assumption that fish proteid always contains 
16 % of nitrogen. But, since the fat solvent always seem to 
extract something which is not a true saturated or unsaturated 
oil or fat, but which contains nitrogen, it must be overestimated 
and the “proteid”” must always be underestimated for the 
same reason. The manipulative error of estimation of “ fat ”’ 
is very small; that of estimation of NV may be taken as about 
+ 0:05 %, and that of estimation of “‘ Proteid ” as about + 
6°25 x 0:05 %. | 
From the point of view of “ dietetics,’ “ calories ” and 
the like, in connection with public food problems these errors 
do not matter since they must be negligible when compared 
with other sources of incertitude that arise. 
The Nature of the ‘‘ Maturation” Process. 
It is well known that pilchards, herrings, sprats, mackerel 
and other Clupeoid fish, which are processed and packed 
“a la Sardine” must be matured or ripened. When newly 
packed the bones are not softened, and the taste and smell 
are not those expected. The fish are “ raw ”—even if they 
have been cooked in the ordinary sense of the term, and the 
taste is only that of the specific cooked fish. Maturation, or 
ripening is the result of simply allowing the tins to stand 
unopened for a considerable time, 6 months to 4 years, during 
which the fish continually improve, and the flavour becomes 
increasingly “richer.” This process of maturation may continue 
for about 10 years. 
The bones soften until they can hardly be distinguished 
(in the mouth) from the flesh. The scales (in the case of - 
pilchards) do not seem to undergo any change. The flesh 
becomes very soft and pasty, so that fish in a watery medium, 
like tomato sauce, or the media used in “‘ marinaded ”’ products 
become so tender that they can hardly be handled without 
Ce eee —_——— 
