{23] PROPAGATION OF WHITEFISH AT NORTHVILLE, MICH. 575 
water temperatures, the difference in favor of eggs of the whitefish must 
be credited to their ready adaptability’to the bulk method of hatching; 
for not only can eggs be developed in this way at a greatly reduced 
outlay of labor and expense, but it is a safe assertion to make, suscep- 
tible of proof by any one who will make a fair trial, that the jar will 
hatch 5 per cent. more eggs than any hatching box now in use, other 
things being equal. The deficit with the latter method may be charged 
to the frequent handling of the eggs, changing from the boxes to the 
picking trough and return, but more than this, to the quick thrusts of 
the nippers amongst the eggs when picking, and which alone unavoid- 
ably injures or kills outright throughout the season nearly 5 per cent., at 
a low estimate. 
The average yield of eggs from the whitefish may be computed at 
20,000 for each female spawner, although as many as 75,000 were taken 
from single specimens in two instances at the islands; but this was a- 
very extraordinary yield, as such extreme fecundity is rarely found. 
Eggs on trays were estimated on a basis of 64 to the square inch and 
in bulk on a basis of 36,800 to the quart, this number being almost ab- 
solutely correct, having been determined by actual count of a fractional 
part of the quantity taken as the standard. 
RETARDING EGGS. 
For the purpose of experimenting with a view to retarding the devel- 
opment of eggs, about 10,000 taken October 31 were spread in double 
layers on flannel trays December 8, and the whole arranged in a small 
refrigerator previously charged with ice and placed in the corner of the 
hatching room farthest removed from the stove. No special care was 
given them other than to keep the chambers well filled with fine ice and 
to give the eggs a weekly picking and sprinkling, care being taken to 
thoroughly drain the trays before replacing, and also to avoid exposing 
the eggs to a greatly increased temperature while being picked, a work 
usually performed in the morning before the room had become too warm 
for the purpose. Very few eggs had died up to December 29, fewer 
probably than if they had remained in water, but of course this is simply 
a matter of conjecture. A record of the temperatures both inside and 
outside the refrigerator was made three times daily. The extremes 
previous to December 29 were: inside 30° and 313°, and outside 30° 
and 46°, The eggs were in splendid condition on the date mentioned, 
when the temperature of 30° was recorded at 8 p.m.; but the next 
morning the temperature of the hatching room had fallen to 21°, 9° 
colder than the refrigerator had been subjected to, while inside, the ther- 
mometer marked 27° and the eggs were all dead. The fact that not a 
single live egg could be found, proves conclusively that eggs of the 
whitefish will not live in an atmosphere of 27°. 
Meanwhile, a larger refrigerator was made, having seven chambers 
fitted with slides of the proper size to admit the flannel trays of the 
