44 FISH—CULTURAL ASSOCIATION. 
tion. Moreover, as in the season of shad-hatching, a full supply 
of water is needed and nota great deal of motion, this is arranged 
for by increasing the feed and raising the lower end of the cen- 
tral or supply tube, so that the delivery of the water from it will 
be under less pressure. This central tube is connected by a rub- 
ber pipe with the pet cock, which furnishes a supply of water 
under a constant head. 
The exit tube serves a double purpose—first, as an outlet for 
the water; and secondly, at our pleasure to remove the layer of 
dead eggs from the surface. This is accomplished at stated 
intervals, say once in twenty-four hours, by loosening the screw 
of the stuffing-box so that the tube will slide readily, pushing it 
down until the dead eggs nearest to the lower end are seen to 
begin to pass off. By allowing it to remain in this position a 
few minutes the layer of dead eggs is swept off entirely. They 
may be either allowed to pass off in the waste, or better, collected 
by screens and fed to the fish in the aquaria, thus serving the 
double purpose of preventing the fouling of the water and fur- 
nishing a very appropriate food for many varieties of fish. When 
the period of hatching approaches, instead of allowing the water 
from the hatching jars to pass directly into the sinks, it is neces- 
sary to conduct it through the collecting jar. This is precisely 
similar in construction to the hatching jar. Indeed it is the 
hatching jar with some special arrangements to adapt it to its 
new purpose. The water passes from the hatching jar through 
the rubber tube into the eccentric opening of the receiving Jar. 
he tube and opening then serve for the inlet instead of the out- 
let of the water. On the lower end of the central tube is placed 
a wire frame, over which is drawn a bag made of cheap cotton, 
the texture of which is such as to permit the water to strain 
through, but the meshes of which are so fine that the suction of 
the water will not hold the young fry against it, as would be 
the case if a wire screen were used. 
The surface of this strainer should be as large as is convenient. 
It is adjusted to the lower end of the central tube in such posi- 
tion that the end of the tube is in the centre of the wire cage, or 
as nearly so as possible, the object of this being to make the 
draw of the water equal in all directions. The water is allowed 
