10
J. E. SHELBOURNE
through this hole, water overflowed laterally from (A) into pockets B
bnd B’, escaping into the middle chamber through slits in the bottoms
of these two pockets. The outlet chamber (D) of the whole compartment contained a siphon outlet consisting of a vertical pipe, the
upper end of which supported a deep, loose-fitting cap held in position
over the pipe by means of internal spring clips. The outlet pipe jutted
op through a seal in the bottom of chamber D, and with the cap
removed, formed a constant level overflow system. With the cap in
position, however, air waa sucked out of the space between water level
ad the top of the cap with outflowing sea water, until a siphon effect
raa achieved. Water then ran out of the whole compartment faster
than it flowed in, and the level quickly dropped until it reached the
open end of the cap, whereupon air entered and the siphon was broken.
The compartment then refilled.
The middle chamber (C) contained a removable wooden box into
which the fertilized eggs were placed. The bottom of this box was
lovered with linen scrim, and one of the wooden ends was pierced by
i hole coinciding with that in pocket A of the supply chamber. With
the box positioned firmly in the middle chamber, a water jet flowed
through the holes with sufficient force to keep the eggs in constant
motion. Egg movement was further intensified by water currents
through the bottom slits of pockets B and B’, and also by the intermitknt rise and fall of water level in the compartment. Adjacent compartments could be connected by watertight gates in the dividing wall.
These coincided with outaway portions in the side walls of the removJle boxes. It was a simple matter to transfer floating cod eggs from
one incubator to another by overflow across the dividing wall, thus
facilitating the bulk removal of dead, sunken eggs from temporariIy
evecuated tanks.
The American and European hatchery programmes were launched
on im industrial scale without adequate background research. Very
little indeed waa known about the environmental requirements of
m&rine fish and their eggs in captivity, and hatchery affairs were
therefore conducted in an empirical manner. Some of the difficulties
encountered in the United States were reviewed by Atkins (1889),
who reported troubles with fish and egg supplies, temperature control,
egg overcrowding, faulty incubators and rust in hatchery pipes.
Inedequate filtrrttion of incoming sea water, and lack of salinity
@ntrol during the spring thaw, also caused high egg mortality. The
Proentage hatch was often very low indeed; in 1887, for instance,
10% of all collected eggs died at Glouceshr Harbor, and 76% at
~oods Hole, the losees being heaviest during very cold weather.
J. E. SHELBOURNE
through this hole, water overflowed laterally from (A) into pockets B
bnd B’, escaping into the middle chamber through slits in the bottoms
of these two pockets. The outlet chamber (D) of the whole compartment contained a siphon outlet consisting of a vertical pipe, the
upper end of which supported a deep, loose-fitting cap held in position
over the pipe by means of internal spring clips. The outlet pipe jutted
op through a seal in the bottom of chamber D, and with the cap
removed, formed a constant level overflow system. With the cap in
position, however, air waa sucked out of the space between water level
ad the top of the cap with outflowing sea water, until a siphon effect
raa achieved. Water then ran out of the whole compartment faster
than it flowed in, and the level quickly dropped until it reached the
open end of the cap, whereupon air entered and the siphon was broken.
The compartment then refilled.
The middle chamber (C) contained a removable wooden box into
which the fertilized eggs were placed. The bottom of this box was
lovered with linen scrim, and one of the wooden ends was pierced by
i hole coinciding with that in pocket A of the supply chamber. With
the box positioned firmly in the middle chamber, a water jet flowed
through the holes with sufficient force to keep the eggs in constant
motion. Egg movement was further intensified by water currents
through the bottom slits of pockets B and B’, and also by the intermitknt rise and fall of water level in the compartment. Adjacent compartments could be connected by watertight gates in the dividing wall.
These coincided with outaway portions in the side walls of the removJle boxes. It was a simple matter to transfer floating cod eggs from
one incubator to another by overflow across the dividing wall, thus
facilitating the bulk removal of dead, sunken eggs from temporariIy
evecuated tanks.
The American and European hatchery programmes were launched
on im industrial scale without adequate background research. Very
little indeed waa known about the environmental requirements of
m&rine fish and their eggs in captivity, and hatchery affairs were
therefore conducted in an empirical manner. Some of the difficulties
encountered in the United States were reviewed by Atkins (1889),
who reported troubles with fish and egg supplies, temperature control,
egg overcrowding, faulty incubators and rust in hatchery pipes.
Inedequate filtrrttion of incoming sea water, and lack of salinity
@ntrol during the spring thaw, also caused high egg mortality. The
Proentage hatch was often very low indeed; in 1887, for instance,
10% of all collected eggs died at Glouceshr Harbor, and 76% at
~oods Hole, the losees being heaviest during very cold weather.