160 THE BREEDING OF ANIMALS 



The most notable examples of acquired development 

 are to be found in the human family. Through the life- 

 time of a man the mental and physical qualities may be 

 greatly modified. An individual may acquire great 

 mental power. Such acquirement may have been 

 achieved under very great difficulties. The particular 

 kind of mental efficiency represented by the develop- 

 ment of such an individual may be an exceedingly desir- 

 able characteristic of the greatest value to the human 

 race. Its transmission by heredity would be desirable 

 for the good of the race. Can such acquired characters 

 or habits be transmitted? The answer to this question 

 is important to the development of the human race. It 

 is likewise of the greatest economic importance to the 

 breeder of domestic animals. In the domestic animals 

 the highly artificial characters possessed by the improved 

 forms of cattle, horses, sheep and swine are very largely 

 due to the development or good handling to which these 

 animals have been subjected. If the results of the 

 high degree of development of one generation are to 

 fundamentally influence the characters of the next, then 

 a new significance will be given to the effects of environ- 

 ment. 



150. What are acquired characters? The use of 

 the term acquired characters to indicate entirely different 

 facts has given rise to some confusion in the consideration 

 of this subject. In one sense no character is ever trans- 

 mitted. Only the determiners which give direction to 

 the developing characters of the animal or plant are 

 actually inherited. The characters themselves develop 

 out of and are determined by the fundamental constit- 

 uents of the germ substance. Thus the appearance of 

 the secondary sexual characters of the male at puberty 



