THE GENERAL ASPECTS OF ANIMAL BREEDING 447 
testify eloquently to the opportunity for improvement which exists in 
the livestock breeding industry of the country. 
The Art of Breeding.—As an inevitable result of the years of careful 
management to which livestock has been subjected, there has grown up a 
considerable fund of empirical knowledge having to do not only with the 
best methods of caring for and feeding animals, but also with the best 
methods of mating them to ensure the production of the proper type of 
offspring. Many systems of breeding have been subjected to rigid 
practical tests; tests which have been duplicated and reduplicated in 
single breeds and in different breeds. Consequently, although many 
mystical ideas have often survived over long periods and although 
some still have their following among practical men, particularly if they 
happen to have been championed by breeders of outstanding success, 
nevertheless the tendency has been slowly, but surely, to separate the 
true from the false. Animal breeding practice in its best form has 
reached an exceedingly high state of development; the old herdsmen who 
have grown up among their livestock, although their scientific training 
may be very limited, are masters of the art of breeding. Like artists in 
general they do not need to know very much about the composition of 
the materials with which they work; what they do need to know, and in 
truth what some of them do know marvellously well, is how to utilize 
the materials to the best advantage. 
The Problems of Animal Breeding.—Here we may be permitted to 
digress a moment in order to emphasize the fact that the problem facing 
the animal breeder is different from the one facing the plant breeder. 
There are many reasons for this fact some of which it may be well to state 
here in order that no misunderstanding as to the general applicability 
of the laws of variation and heredity may arise. In the first place in 
plant breeding we are more particularly concerned with questions of 
local adaptation and matters of kindred nature. Plants are notoriously 
susceptible to differences in the environment because of their close re- 
lationship to conditions of soil and climate. It is a familiar experience 
to find that varieties of plants of proven worth in one locality fail miser- 
ably to live up to their reputation in some different region. Now toa 
certain extent this is true also of animals, but it must be patent to anyone 
that livestock is on the whole relatively independent of environmental 
influences. Man himself has migrated into new regions from the begin- 
ning of time, usually taking his herds with him. Inclemencies in the new 
surroundings have been met by construction of rude shelters or by seasonal 
emigrations. In the present time the construction of suitable shelters 
is, indeed, a universal practice, so that today domesticated animals ex- 
hibit an independence from the environment almost as great as that of 
man himself. As a consequence of the lesser need of considering envi- 
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