4 U. S. BUREAU OF FISHERIES 
three short legs are soldered to the lower end to hold the tube above 
the bottom of the glass jar. 
The troughs are placed one above another at a proper distance to 
accommodate the type of jar used. They are held together by a 
support made of 4 by 4 inch timbers, so placed that a row of six 
jars can be accommodated between each set of stanchions. At the 
Put in Bay hatchery there are six rows of jars, making 36 jars be- 
tween each set of stanchions. This type employs the “stageer sys- 
tem in placing the jars on the battery, by which method “each jar 
of the top row supplies the jar immediately underneath. The 
troughs are held together in the stanchions by one-half inch bolts, 
with nuts and washers at each end, which also act as supperts to 
the trough. 
Beginning at the top trough, the water supply enters one end and 
supplies each jar on the top row, which in turn discharge into the 
trough next below. The surplus water passes through the tin over- 
flow at the opposite end and into trough No. 2, which projects from 
8 to 10 inches beyond the top trough at one end. This alternate 
system is continued ‘until the water finally is conducted into the 
receiving tank situated at the end of the battery. 
This tank i is 24 inches deep, 3 feet wide, and of sufficient length 
to receive the water from two batteries. Provision is made at one 
end of the tank for a screen and an overflow for the diversion of 
part of the water. The water remaining passes into a series of fry 
tanks arranged at right angles to the receiving tank, conneeGion 
between them and the fry tanks being made by 1 means of a 2-inch 
pipe set 1 foot below the surface of the water and provided with a 
stopcock. At the Put in Bay hatchery four fry tanks, set in series 
of two, receive their water supply from the retaining tank. Each fry 
tank is provided with a screen near its lower end, and a similar con- 
nection is made between the fry tank and the receiving tank. The 
fry tanks are 24 inches high, 3 feet wide, and usually 16 feet long. 
Pike-perch eggs are lighter than many others, and as they hatch 
in comparatively warm water they become fungused very soon 
after death. The hatchery water supply, therefore, should be clear. 
If it contains any considerable amount of sediment the defective 
eggs soon will become so loaded with it that they will attain the 
same specific gravity as the living ones and sink in the egg mass, 
forming lumps that can be removed only by screening which is 
always more or less injurious. Even the live eggs will become coated 
with it, interfering with the proper working ‘of the jars. Where 
clear water is used, the fungused eggs remain buoyant, float on top 
of the egg mass, and can be removed easily without loss or injury 
to the living ones. 
With a water temperature above 55° F., and a moderately turbid 
water supply, it is difficult to maintain a proper circulation in the 
jars. Under such conditions fungus develops on the dead eggs so 
rapidly that it is impossible to prevent their mixing to some ‘extent 
with the good eggs. The small percentage of living eggs contained 
in the mass of dead ones must then be drawn off and either planted 
in suitable outside waters or held in separate jars, known in fish- 
cultural parlance as hospital jars, until incubation is completed, only 
a comparatively small number of eggs being placed in each jar. 
