34 FISH—-CULTURAL ASSOCIATION. 
SECONDED LY. 
HISTORY OF THE EXPERIMENTS LEADING TO THE 
DEVELOPMENT OF THE AUTOMATIC 
PIsh-HA CHING JAK 
BY MARSHALL MCDONALD. 
The work of practical pisciculture was, until a comparatively 
recent period, confined for the most part to the hatching of the 
different species of the salmonide. The incubation of the eggs 
was at first effected in troughs having the bottoms covered with 
a layer of gravel, upon which the eggs were placed, and over 
which a current of fresh water was allowed to flow. 
In succession followed the ‘‘grill system” of M. Coste and 
the different devices of movable trays now in common use for 
handling this class of eggs. In all these various methods the 
separation of the dead eggs from the live ones was effected by 
means of hand-picking. The necessity for the separation, al- 
though not so urgent in the case of the eggs of the salmonidz 
as in that of those eggs which develop in warmer waters and in 
much shorter periods of time, still entaila vast amount of labor 
in connection with the hatching operations. 
Although the ingenuity of our fish-culturists has greatly im- 
proved the forms of hatching-apparatus for these heavy eggs, 
yet up to a comparatively recent period no other effectual means 
of separation than that above indicated has been found prac- 
ticable. The United States Fish Commission, in the develop- 
ment of its work, had presented to it the necessity of dealing 
avith the eggs of the whitefish and the shad upon a scale unpre- 
cedented in the history of fish culture. Millions of eggs were 
to be hatched where fish-culturists formerly handled only thou- 
