CHAPTER XII 



EVOLUTION OF SEX 



There is noted a cumulative effect of heredity which is 

 attained by the simple conjugation of single cells as exam- 

 ined in the last chapter. When two cells approach and amal- 

 gamate, after a difference of experience which induces in 

 them an affinity or attraction, it is clear that some of their 

 properties are added, and not merely averaged. 



Observation of conjugations and especially of hybrid 

 unions; indicates that if one creature has a heredity which 

 is a chain of ten experiences, and the other a chain which 

 records eleven, then the resulting heredity of the combined 

 cell is eleven experiences; the first ten which were alike in 

 both (because they are creatures of the same order or race) 

 and the last, or eleventh, which was recently acquired by one, 

 being a new evolution still in experimental stage. The stu- 

 dent who has not access to biology of primitive life, can see 

 this process of added heredity in common domestic animals. 

 It can be observed, for example, when the young appear 

 possessed of certain character of recent development, which 

 was possessed by one parent and not by the other. Thus 

 the possession of horns by cattle or sheep may be the result 

 of one parent's heredity even when bred with another defi- 

 cient in them. The effort to breed hornless cattle has suc- 



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