EGGS AND THE HEN 333 
few hours’ warmth of the required temperature brings 
into activity all the power lying dormant from the time 
the egg was laid. Afer five or six hours, little finger- 
like processes begin to creep out from the blastoderm and 
gradually distribute them- 
selves over the whole of the 
yolk. 
Eggs raised for commercial pur- 
poses should not be fertilized, and 
they should be stored in a cool place 
during collection for shipment. Fer- 
tile eggs in the hot days of summer 
show signs of incubation very 
quickly. If roosters are kept away 
from the laying flock and a cool 
basement is chosen for the storage 
place, the eggs will remain fresh 
much longer and they can be shipped 
a longer distance. 
7. Development of embryo. 
—A fertile egg incubates very 
rapidly if provided with the 
proper degree of heat. After 
only 18 hours the head of the 
future chick, with eyes enor- 
mously developed, and _ the 
spinal column, are plainly dis- 
cernible under the microscope. 
After 40 hours there is a com- 
plete blood circulation, the 
heart is formed and beating 
commenced, and the blood ves- 
sels have spread over a consid- 
erable portion of the upper 
yolk. These are of a dual 
character; some are arteries, 
taking blood away from the 
DEVELOPMENT OF CHICK 
a, eighteen hours; b, second day; 
c, forty hours; d, third day; e, 
fourth day; f, fifth day; g, just be- 
fore hatching; h, at peeping time; 
and i, nearly out of shell. 
