METHODS OF HATCHING FISH EGGS. 
211 
foreign matter to enter the jar. The presence in the jar of anything but water and eggs 
renders a proper motion of the mass impossible, and generally results in the loss of a 
large proportion of the eggs. No absolutely delinite law can be established as to the 
correct number of eggs for each jar, because the conditions are never the same in any 
two hatcheries, and vary from day to day in any particular hatchery. With shad eggs it 
will not generally be found advisable to put more than three quarts, or about 85,000 
eggs, in a jar. If the water is very clear, or temperature low, an additional pint of 
eggs can be safely addeil ; or if the eggs are known to be very bad the quantity can 
be increased to a gallon (about 115,000 eggs), provided the boiling motion, at first, be 
very slow. After thirty minutes, the dead eggs being partially separated, may be 
drawn off and a faster motion given to the remaining live eggs. Whitefish eggs when 
first taken are somewhat glutinous, and, if not properly managed, liable to become 
“lumpy” and require breaking up or separating. When the whitefish are new they 
should be worked quite rapidly under a full current. (This also applies to a limited 
extent to shad eggs.) Care should be exercised at this point that the end of the inlet 
tube reaches nearly to the bottom of the jar for the double purpose, first, that the eggs 
may not be caught under the inlet and pounded on the bottom of the jar; and, second, 
that the boiling motion may be increased without any unnecessary waste of water. 
An experienced workman can easily tell when the eggs are entirely “ free ” and reduce 
the motion accordingly. I am aware that the fish-culturists of the lake region claim 
that it is absolutely necessary to have an open jar in which to hatch whitefish, to more 
conveniently “feather” or separate the lumps; but actual practice has determined 
that the McDonald jar is capable of satisfactorily incubating whitefish eggs in all 
stages of hatching. When the whitefish eggs are new, three quarts (about 108,000 
eggs) is a sufficient quantity for a jar. As they advance to the eye-spot period the 
quantity of eggs may be doubled, so that each jar will have between 4 and 5 quarts 
(from 145,000 to 180,000 eggs). This will not only leave fewer jars for attention, but 
economize water. 
The requisite number of eggs being in the jar, it is put in its proper position on the 
hatching- table and closed. Before closing, be sure- that both the inlet and outlet tubes 
slide freely in their stuffing boxes, and that the rubber washer as well as the screw-cap 
is in its proper position. If the tubes should have become gummed so as not to 
slide freely, this can often be remedied by allowing water to trickle down around the 
binding screws. To close the jar, turn on the water, place the feed-tube in the jar, 
turning off the water immediately after the feed-tube has passed beneath the surface of 
the water in the jar. The object of this is to expel all the air from the feed-tube, else it 
would rise in bubbles, throwing a portion of the eggs out through the outlet-tube. 
After expelling the air from the feed-tube place the washer and metal plate in position 
and screw down the screw cap. When the water is turned on semi-buoyant eggs for 
the first time the action is often peculiar, and the jar should be watched closely until a 
regular motion has been established. When eggs from any cause have stood fifteen 
or twenty minutes in the jar before the water is turned on, they do not readily yield 
themselves to the boiling motion, but seem to have become packed so that they tend 
to rise in a solid mass to the top of the jar. By quickly starting and stopping the cur- 
rent the mass is readily disintegrated. Ajar should never be left till the attendant 
is thoroughly satisfied that the regular boiling motion has been established. The 
degree or intensity of motion the egg should have will be found to vary not only with 
