228 PRINCIPLES OF POULTRY BREEDING 
if the blood elements which they inherited from their parents are 
to be given an opportunity for full development. 
Another important factor in the environment is the supply of 
feed, which must be sufficient in amount, wholesome, and of the 
right degree of concentration. Instances have been known in 
which the excessive forcing of mature birds during their first laying 
season had so weakened their vitality that their records in egg pro- 
duction were not nearly as high as those of their parents, whereas, 
after selected mating and breeding, they should have excelled them 
if conditions had been right. Birds which are kept by man in a 
state of domestication are dependent upon him for shelter and 
feed, which largely make up their environment, and a careful and 
proper regulation of this is essential if the inherited qualities are 
to be given opportunity for their highest development. 
Functional Activities —From the time the chick is hatched, the 
degree of development which it will ultimately attain depends in 
large measure upon the extent to which it performs its normal 
bodily functions. The normal activity of an organ increases its 
power to perform its function in a healthy and normal manner. 
For example, the blacksmith by the constant use of his right arm 
gradually attains a greater muscular development in this than in 
the other arm which does not get this regular and systematic 
exercise. In a similar way the poultryman may, by careful hand- 
ling and feeding of his birds and by allowing them sufficient exer- 
cise, keep them in a normal and healthy condition. Should he 
restrict their exercise, and increase the concentrated feed stuffs, 
such as corn meal, the birds would soon become lazy, take on 
excessive fat, and gradually become poorer and poorer layers until 
the function would finally cease. If the conditions were not cor-- 
rected, the functional activities of the body wouid become con- 
gested and clogged and death would result. 
In the same way it is possible to develop excessively the growth 
and maturity of certain organs; as, for instance, in the forcing of 
pullets for early maturity. The egg-forming organs are stimulated 
to activity before they attain their normal development, and the 
resulting eggs are small in size, in many instances containing weak 
germs, especially if the pullets are mated to males of early devel- 
opment. Their eggs when hatched will produce chicks small in 
size and of light weight, many of them cripples and weaklings. 
Not only will the eggs be small, but the bird itsclf, because of its 
early maturity, will never attain the size and shape which would 
