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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