316 FARM ANIMALS 
the embryos in the eggs the longer the heat is retained. 
Incubator eggs are not cooled after the eighteenth day. 
8. Testing the eggs.—When the eggs have been hatch- 
ing seven days they should be tested. The testing of 
eggs is very easy, and after a little experience one should 
experience no difficulty 
in distinguishing the 
good from the bad. 
The proper way to tell 
a fertile egg is to take 
it between the thumb 
and forefinger and 
hold it before a strong 
light. If it is perfectly 
clear within, it is not 
1, common tester; 2, egg properly held; 3 2 = 
incubator lamp; 4, "untested eggs; 5, infertile fertile; if, on the con- 
ee Ce ES REE trary, a little black 
speck with red lines is seen to float inside of it, looking 
more or less like a spider in its web, it is certain to be 
fertile. The same examination should be made on the 
fifteenth day. The infertile eggs should be removed and 
kept to feed the chicks later. 
9. Last days of hatch.—After the eighteenth day the 
machine is closed and not disturbed, except to fill and 
trim the lamp until the hatch 
is complete. While the eggs are 
hatching the temperature of the 
machine may go as high as 105, 
or even 107 degrees; this is 
caused by the animal heat 
given off by the chicks, and 
no attempt should be made 
at all to lower the tempera- 
ture if the machine has been 
TESTING Eccs 
THEIR Last Day THERE 
