288 MANAGEMENT OF BREEDING STOCK 
able type which would not produce living chicks can at this time 
be disposed of at a profit. If put into an incubator, they would 
result only in a hatch of weak or malformed chicks, and the revenue 
which might have accrued from the sale of eggs would be lost. 
Keeping Eggs for Hatching.—Many eggs are ruined for hatch- 
ing purposes during the time they are held previous to incubation. 
Eggs should be kept at a relatively low temperature, 50° F. being 
the most desirable. Experiments show, and embryologists tell us, 
that the embryo in the egg begins to develop at a temperature 
of 70°, but if this temperature is not maintained it immediately 
dies. During this short period it will not have attained any size, 
and cannot be detected by candling, but may be classed as 
Fia, 140.—Desirable and undesirable types of hatching eggs. Upper row quite uniform 
as to size and shape; lower row, too long, too round, or with imperfect shells. 
infertile. This fact undoubtedly accounts for the exceptionally 
high percentage of apparently infertile eggs on farms and small 
poultry plants during the late winter and early spring, when, in 
order to keep the eggs from freezing, they are placed behind the 
kitchen stove. ; 
It is advisable to place hatching eggs so that they can be regu- 
larly and carefully turned once a day. The embryo floats in the 
upper portion of the yolk, and, if the egg is left in one position 
for a considerable time, the yolk may come into closer contact 
with the shell, and, if not turned, it may become attached. More- 
over, if eggs are not regularly turned, the air cell will assume an 
abnormal position, since the fluid in an egg has a tendency to 
settle and the air to rise. Eggs left in one position for a consider- 
