PRACTICAL AND SCIENTIFIC BREEDING 
the offspring of bird from two much better than the offspring 
from yard one. The breeder should keep the prepotent sire 
and his offspring rather than the more perfect male, who fails 
to stamp his traits upon his get. 
Normally a child has two parents, four grandparents, and 
eight great-grandparents. Now, when cousins marry, the 
great-grandparents of the offspring are reduced to six. The 
mating of brother and sister cuts the grandparents to two, 
and the great-grandparents to four. Mating of parent and off- 
spring makes a parent and grandparent identical and likewise 
eliminates ancestry. Inbreeding means the reduction of the 
number of branches in the ancestral tree, and this means 
the reduction of the number of chances to get variation, be 
they good or bad. 
Inbreeding simply intensifies whatever is there. It does 
not necessarily destroy the vitality, but if close inbreeding is 
practiced long enough, sooner or later some little existing 
weakness or peculiarity would become intensified and may 
prove fatal to the strain. For illustration, suppose we began 
inbreeding brother and sister with a view of keeping it up 
indefinitely. Now, in the original blood, a tendency for the 
predominance of one sex over the other undoubtedly exists 
and would be intensified until there would come a generation 
all of one sex, which, of course, terminates our experiment. 
Inbreeding has always been tabooed by the people generally. 
Meanwhile the clever stock breeders have combined inbreed- 
ing with selection and have won the show prizes and sold the 
people “new blood” at fancy prices. 
Unintelligent inbreeding as practiced on many a farm, 
results in run down stock, not so much from inbreeding as 
from lack of selection. Out-crossing or mixing in of new 
blood is better than hit-or-miss inbreeding. Intelligent in- 
breeding is better still. 
Scientific Theories of Breeding. 
The main tenet of Darwin’s theory of racial inheritance or 
evolution, was that changes in animal life, wild or domestic, 
were brought about by the addition of very slight, perhaps 
imperceptible, variations. He argued that the giraffe with the 
longest neck could browse on higher leaves in time of drought 
and hence left offspring with slightly longer necks than the 
previous generation. ’ 
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