The Emdencefrom Intellectual Differences. 251 



well as in the reproduction of the individual. The ade- 

 quate statement of the evidence upon which this gener- 

 alization rests, or even a full statement of the general- 

 ization itself, with its qualifications, would be out of 

 place here, but the facts which have been given seem to 

 be sufficient to warrant its use as one step in our argu- 

 ment in regard to the relations of the sexes. From this 

 as our basis we will now trace the evolution of sex. 



Among the lowest organisms, animal and vegetable, 

 multiplication is usually by the various forms of asexual 

 generation, budding or fission, or cell-multiplication — 

 an organism which has by ordinary growth increased in 

 size beyond the limit of exact harmony with its environ- 

 ment, dividing in this way into two, like each other as 

 well as like their parent. In this way the preservation 

 of the established characteristics of the species — hered- 

 ity — is provided for, but in order that progress should 

 take place, by the preservation of favorable varieties, 

 variation must also be provided for. This is accom- 

 plished by the process which is known as conjugation: 

 two protoplasmic organisms approach, come into con- 

 tact, and a transfusion or mixture of the semi-fluid con- 

 tents of their bodies takes place. The result of this 

 process is the production of new^ individuals which, de- 

 ]'i\;ing their protoplasm from two parents which are not 

 exactly alike, are themselves different from either of 

 them, and have individual peculiarities which are, it is 

 true, the resultant of the peculiarities of the parents, 

 but which are nevertheless new variations. 



In the simplest forms of conjugation the functions of 

 both parents appear to be identical, but in oi'ganisms 

 which are a little more specialized we find male and fe- 

 male reproductive bodies, and the offspring is the result 

 of the union of the male element of one individual with 



