230 PRINCIPLES OF POULTRY BREEDING 
tinctive peculiarities common to different breeds. Each of the 
eleven different groups into which all birds have been divided has 
its distinctive peculiarities. These relate to physical form, color, 
and functional development. This is further seen in the division 
and subdivision of each breed into varieties. So strong may be 
the resemblance between them that it is often possible, from a 
flock of considerable number, to pick out daughters or, more often, 
sons from a given mating, because they possess certain family or 
mating characteristics peculiar to one or both of the parents. 
These resemblances are not accidental, but are the direct expres- 
sion of this, the greatest law of breeding. 
Benefits from this Law.—The actual benefits from this law may 
be grouped into three divisions: 
It makes possible the improvement of poultry by breeding to a 
fixed standard. The highest degree of perfection which it is pos- 
sible to attain will probably never be reached so long as the stand- 
ard of excellence is only gradually raised. 
It enables breeders to maintain improvement after it is once 
established. Everywhere in nature there is a strong tendency 
toward deterioration, and the proper manipulation of individuals 
by the action of this law will aid in checking this retrograde tend- 
ency. Poultry, if neglected for even one or two generations, are 
especially susceptible to this process of deterioration, the degree’ 
depending upon the vitality and purity of the blood when the race 
was at its best. 
By the action of this law it is possible to fix new types and 
standards after they have once been created by a selection of 
variants. The tendency of poultry breeding in the past has been 
to attempt to create new breeds. In many cases the breeder did 
not clearly understand just what type he was after, or the exact 
value of a desired characteristic, could it be secured. The result 
is that we have to-day a great many breeds of poultry which are 
duplicates in many respects. The great need in the immediate 
future is the improvement of well-established breeds rather than 
the creation of new ones. 
Heredity in Cross Breeds.—By hybridizing is meant the crossing 
of two varieties, or breeds, the object being to produce a combi- 
nation of the desirable qualities of the two. At some future time 
the qualities of three or more breeds may be combined. For ex- 
ample, let us suppose that a breeder who had produced an excellent 
strain of single-comb White Leghorns found that, owing to the 
