PIKES AND PIKE PERCH 13 
In order to secure perfect cleanliness, it is advisable, once or twice 
a year, to treat the whole system of troughs and pipes through 
which the water runs with a clear solution of chloride of lime, 
beginning with the supply tanks, which should be washed thor- 
oughly inside, and following down until all have been cleansed, 
opening each faucet or cock during the procedure. In this way the 
system is freed at small expense from Infusoria and other forms, 
which at times are very troublesome and more or less destructive 
to the eggs. This work should be done just before whitefish eggs are 
to be placed in the jars in the fall, and again in the spring as soon 
as the whitefish eggs and fry are all disposed of and before the 
pike-perch eggs are received. If these periods overlap, one battery 
at a time can be treated. After treatment the tanks must be washed 
thoroughly and the whole system flushed for an hour or more. For 
this purpose chloride of lime is much more effective than common 
lime. The preparation is made by dissolving 5 pounds of chloride 
of lime in 10 gallons of water, and after it has settled the clear solu- 
tion is decanted and added to approximately ten times its bulk. 
When the eggs are placed in the jars 24 hours after taking, allow- 
ance is made for some additional swelling. Accordingly 314 quarts 
of eggs are placed in each jar upon setting them up. These will 
swell to 4 or 414 quarts at the end of three days, and this is the 
amount that can be worked to best advantage. The eggs are manip- 
ulated with the least possible amount of water that will keep them in 
motion throughout. More than this is harmful and will cause rup- 
tured yolks. ‘The jars are inspected daily, and any that are working 
too fast or irregularly are adjusted. 
The eggs are semibuoyant and very adhesive. A single, large, 
spherical oil drop floats at the top of the yolk mass. The germinal 
disk is on the side of the yolk. The first cleavage of the disk ordi- 
narily takes place in five or six hours in a water temperature of 
45° to 50° F. Unequal division of the disk is rare, though it some- 
times occurs, while with the whitefish and many other species 
inequality of cleavage is the almost universal rule. 
In a water temperature of 45° to 50° the form of the embryo may 
be distmguished under a low-power magnifying glass within four 
days, and at the end of the sixth day the eye spots usually can be seen 
by the unassisted eye. By this time the pigment cells or color stars 
also may be seen with a microscope of low power, as well as the pul- 
sations of the heart and the coursing of the blood through the vessels, 
the red corpuscles being distinguishable. 
At this stage any monstrosities, malformations, and other deform- 
ities may be discovered easily. These consist of embryos with 
double heads (the most common form), more than the normal number 
of eyes, curved spines, and various others, some so slight as to be 
scarcely discernible. 
The eggs hatch in from seven days at a mean water temperature 
of about 57° to 28 days at about 40°. At a temperature of about 
48° the eggs will hatch in 18 to 20 days and produce vigorous, 
healthy fry. 
As the fry of the pike perch are about three-sixteenths inch in 
length, very fine brass-wire cloth is required to hold them in the 
tanks. The screens in use at the several pike-perch hatcheries are 
