SEA-FISHERIES LABORATORY. 13h 
strong brine penetrating the tissues of the fish prevents growth 
of bacteria: it does not render the fish sterile for the brine 
may putrefy when it is diluted with sterile water, but it inhibits 
growth. It permits some degree of autolysis as the result of 
the intra-cellular enzymes of the fish, and this autolytic change 
results in the formation of amino-acids, which dissolve out 
into the brine. 
dite quantity of filtered herring brine obtained by Professor 
Herdman from a barrel of salt herrings which he prepared at 
Port Erin in September of 1917, and which had been kept in 
a bottle from June of 1918, was examined by So6rensen’s 
method for estimating amino-acids. The amino-acid contains 
a COOH eroup, which may take up a basic radicle, and an 
NH, group which may take up an acid radicle. The 
NH, group is neutralised by the addition of previously 
neutralised formaldehyde and the amino-body, which now 
has an acid reaction, is titrated with deci-normal sodium 
hydrate, using phenol-phthalein as indicator. Several estima- 
tions of the herring brine referred to above were made, and it 
was found, as a mean, that 5 c.c. required, for neutralisation, 
18-2 c.c. N/10 NaOH. This gives us (roughly) about 0-5 % of 
nitrogen in the brine, nitrogen present in amino-acids split 
off from the proteid of the fish flesh by autolytic action. 
So also the watery liquid filtered off, through a wet filter 
paper, from a tin containing long-matured herrings, in tomato 
sauce, contained about 0-07 °% of nitrogen. 
It was assumed that the process of proteolysis was similar 
in the case of hermetically-sealed herrings to that indicated 
above. Exactly 4 grms of fresh herring flesh were weighed out 
and ground up with clean sand in a mortar. The fine emulsion 
was washed out from the same into a measuring flask and made 
up to 250 c.c., and successive portions of 50 c.c. each were 
titrated as described above. The mean quantity of N/10 NaOH 
required for 50 c.c. was 1:1 c.c. 
Brine-frozen sprats packed in oil, matured herrings in 
