CHAPTER XXX 
ACQUIRED CHARACTERS IN ANIMAL BREEDING 
The problem of the inheritance of acquired characters has been one 
of the historic battlegrounds of biology. Even yet the question is by no 
means settled, although a considerable amount of information has been 
collected about it. Darwin and Spencer both subscribed to the belief 
that acquired characters might be impressed upon the germinal substance 
and therefore of necessity that offspring might inherit such characters, 
for they saw in an intimate relation between soma and germ-plasm a 
powerful method of evolution. It is not necessary longer to question 
the fact of evolution, but the method of evolution still awaits a satis- 
factory solution. 
In animal breeding especially the question of the inheritance of 
acquired characters is of primary importance because much of the func- 
tional activity of animals depends for its perfection upon carefully de- 
veloped training. It is not enough for the race horse to have a good 
inheritance, it is further necessary that it should be developed and trained 
in accordance with methods known to be favorable to the bringing out of 
its inborn qualities, and this is also true in one respect or another of 
other domestic animals. Now it is only natural for those who have 
carefully attended to the development of the inherent characters of their 
livestock to hope and to expect that their efforts have added something 
of excellence to the hereditary complex of the individual. This in brief 
is the interest which the inheritance of acquired characters has for the 
practical animal breeder. 
The Scientific Problem.—Before taking up the evidence as to the 
inheritance of acquired characters, it is necessary to define as clearly 
as possible what is meant by an acquired character, and to determine 
what sort of proof is necessary in order to establish the inheritance of 
such characters. As many‘writers have pointed out, much futile dis- 
cussion upon the subject has been due to a lack of rigid definition of 
terms. 
Weismann distinguished between blastogenic and somatogenic char- 
acters. The former were such characters as have their origin in the 
germplasm, and the latter are those which are produced by responses 
of the soma or body to surrounding conditions or to its own activities. 
These latter somatogenic variations are the acquired characters of evo- 
lutionary literature. Shull’s definition of acquired characters is, per- 
haps, somewhat more precise, namely that acquired characters are 
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