THE PRESERVATION OF SEA FISH 
41 
made solution. After they have been well acted on, they 
may be transferred to the old or stock tank, but I consider it 
most important to remove all specimens from the stock tank 
once a week, take out the solution, and return same through 
four layers of thick house flannel. The process is most laborious, 
but it renders the old stock solution practically free from 
debris, and materially diminishes the chances of staining or 
discolouring the specimens. 
As regards the preparation of fish over half a pound, before 
they are placed in the solution certain details must never be 
omitted. 
The main object is to allow the introduction of the solution 
(and this applies not only to the formalin and soda, but to 
any liquid preservative agent) into the entire mass of animal 
matter which is being preserved as speedily, liberally, and 
uniformly as possible, and this is of much importance in tropical 
climates. 
There are three methods of effecting this, which I will 
describe. 
For instruments you require only two knives ; one of these 
should have a blade of about two inches and the other four 
inches, fitted into a thin handle like a scalpel. The blade of 
the two-inch knife should not exceed three-eighths of an inch 
in breadth, and that of the other about half an inch, but they 
must be sharpened on both sides, thereby forming a sort of 
spear without a high median ridge. 
With fish from half a pound to, say, three pounds, being of 
normal fish proportions, and not semicircular or round as a 
plate as many tropical fish are, you simply insert the knife 
through the ventral orifice upwards to the dorsal line. Draw 
the blade tailwards about one inch, and then manipulate it so 
as to free all flesh from the backbone and the spinal processes. 
Having thoroughly done this, perform the same operation all 
round the shoulders. When doing this, great care should be 
exercised not to damage the internal organs : but at the same 
time, after all the flesh has been separated on one side, a small 
incision should be made from the ventral orifice forwards 
for not more than half an inch, to allow free ingress of the solu- 
tion. Now turn the specimen over, and with the small knife 
treat the side that has not been separated from the bone. 
