204 POULTRY BREEDING 
broken around the shell, the larger end of the shell is 
broken entirely around its circumference and an opening 
is made through which the chick is able to extricate itself 
from its narrow prison and struggle out, a weak and help- 
less creature unable to lift its head or stand on its feet. 
For several hours it lies half dormant, gathering strength 
to struggle more and more until finally it is able to stand 
and walk. Here is seen the wisdom of the chemical com- 
position of the yolk of the egg. While the white of an 
egg has hardly the faintest trace of fat in it the yolk is 
one-third fat. The heat of the mother has up to this time 
kept the fires of life going, but as soon as the chick 
emerges from the shell it requires fuel with which to 
maintain vital heat and the fat in the yolk is this fuel. 
The whole process of incubation is wonderful and in- 
teresting, and one who studies it closely will come to look 
upon the egg as a most wonderful creation. 
INCUBATORS, HOW TO OPERATE.—No incu- 
bator produces as good results in hatching eggs as can 
be produced by using hens; nevertheless incubators are 
recognized as being more profitable to use than hens. An 
incubator may be used at any time in the year, giving the 
poultry breeder an opportunity to hatch his chicks early 
in the season before hens naturally become broody. With 
an incubator a large number of chicks may be hatched at 
one time and the chicks being of the same age have an 
equal chance to grow up. Again, one man can attend to 
the hatching of thousands of chicks when incubators are 
used, while comparatively few sitting hens would occupy 
his whole time. \Vhere 100 or more chicks are to be 
hatched in a season an incubator may profitably be used. 
When those who use incubators extensively can be per- 
suaded to make an estimate of the percentage of the eggs 
