SEA-FISHERIES LABORATORY. 121 
to the fish in the course of the conservation process. This 
saltmg, together with other factors in the conserving process 
alters the percentage of nitrogen present in the proteid fraction 
of the fish, and is no doubt responsible, to some extent, for 
the quality of the product. But the variable percentage of 
nitrogen also depends on the initial condition of the fresh fish : 
mainly, upon the quantity of oil contained in it, and upon the 
sexual condition with respect to the season. Thus, a winter- 
caught, sexually ripe fish containing say 20% of oil is not the 
same thing as a summer-caught, sexually ripe fish containing 
approximately the same proportion of oil (though, as a general 
tule, the ripe winter fish would contain less oil than the ripe 
summer fish). 
The sum “‘ water and oil” depends on the degree of drying 
of the fish in the process of conservation. When this sum is 
relatively low the percentage of “ proteid”’ will be relatively 
high. 
Details of the Analyses. 
LT Fresh Sprats. 
Collected from Penrhyn Weir, Menai Straits, North Wales. 
The fish are mostly immature and are about 8 to 10 cms. in 
length. Throughout the season they are mixed with small 
herrings, and “ whitebait ” are abundant during the summer 
and autumn months. Towards the spring the sprats become 
relatively few and are replaced by herrings about 8 to 12 cms. 
in length. 
Date. Water. Fat. Proteid. Ash. Total.. Nitrogen. 
20.9.18 71°3 8°6 19°5 1°2 100°6 17°1 
4.10.18 75°4 5°] Litt L*6 99°8 158 
18.10.18 73.6 5:2 22°0 2°2 103°0 16°4 
21.11.18 71:6 8°7 18°3 \'7 L00°3 16°2 
6.12.18 69°7 LL‘O L8°5 15 L00°7 16°4 
19.12.18 72.8 79 180 Het L00°4 16°3 
22.1.19 746 59 ye 16 99°8 15°8 
6.2.19 75°5 50 17°3 1-9 99°7 16° 
