612 GENETICS IN RELATION TO AGRICULTURE 
cattle. Here questions of the regularity of breeding, of the type of 
cow best suited for the production of young, of the ability of cows to 
provide sufficient nourishment for their offspring, of adaptability to 
the conditions of climate and to the other environmental features of 
the locality in which they are produced, and many other considerations 
enter in. Finally we have the ideal breed type to consider: the animal 
must possess those characters which distinguish Shorthorns as a breed 
from other beef breeds such as Aberdeen Angus, Galloway, or Hereford 
cattle; and very likely it will be necessary in order for it to meet with 
favor that it display those particular characteristics of the Shorthorn 
breed which mark it as belonging to some favorite family or strain. 
We have seen how difficult it is to deal with Mendelian experiments 
involving differences in five or six definite, allelomorphic pairs of factors; 
how much more difficult must it be to deal with all the variable considera- 
tions which enter into the discussion of the method of constructing an 
ideal beef type of Shorthorn cattle. And yet even in the face of all 
these requirements the results of intelligent, systematic breeding opera- 
tions are surprising in excellence and uniformity of product. When we 
consider this fact we can only become more strongly convinced of the 
definite, knowable operation of the laws of heredity. 
But these factors which enter into the determination of ideal types 
are largely considerations outside the pale of genetics proper. These are 
the matters which must be added to a knowledge of genetics in order to 
complete the equipment which would be at the command of the animal 
breeder. To this knowledge, also, must be added information bearing 
on the technique of managing breeding herds in order to realize the full 
returns which it should be possible to secure. This information will 
include a large and varied range of topics such as the methods of feeding 
breeding stock and of developing young stock, the determination of the 
proper number and use of service animals, methods of coping with disease 
of various kinds; a knowledge of methods and appliances by which the 
greatest possible use may be made of particularly excellent animals, such 
as by artificial insemination, and a thousand and one items to recount 
which would only make this discussion more tedious and uninteresting. 
But these elements are none the less essential to the equipment of the 
successful animal breeder. 
So we come to the end of our account of genetic principles in animal 
breeding, realizing very keenly the limitations in our knowledge, and 
the inadequacy of the principles of genetics alone and unsupported to 
serve as a working equipment for the practical animal breeder. But we 
take a deal of courage and satisfaction out of the fact that a consideration 
of those principles has a proper and important part to play in animal 
breeding, first by the emphasis which it lays upon heredity as a factor 
Digitized by Microsoft® 
