ORIGIN OF LIFE, SEX, SPECIES, ETC. 227 



obviously much remains to be done, if, as reported, 

 the females and the males are under certain con- 

 ditions capable of reproducing without the assistance 

 of the other sex. 



In the highest order of sexual development, each 

 substance is contained in a separate well-developed 

 organ of reproduction, and this is, then, part of the 

 organism of a separate individual, distinguished as 

 being of either male or female sex, and neither sex 

 at this stage can reproduce without the other. 

 Evidently the process of concentration with like, 

 and dissociation from unlike, has nearly reached 

 perfection in this kind of reproductive materials. 



Origin of Species 



In sexual forms of life, as explained in Chapter I, 

 the preparation for reproduction begins with the 

 conjugation of two substances derived from two 

 organisms of opposite sex. If the two organisms 

 resemble each other, then the fertilized ovum, 

 which is the result of the conjugation mentioned, 

 is usually competent to initiate primary cell division 

 and segmentation. If they resemble each other 

 closely enough to be classified as belonging to the 

 same species, then, cseteris paribus, a highly complex 

 series of cell divisions tending to the evolution of 

 a new organism continues during days, months, or 

 even years, through the embryonic, infant, and 

 adolescent periods, until an adult resembling its 

 parents has been evolved out of each fertilized ovum. 



