THE STRUGGLE FOR THE LIFE OF OTHERS 317 



all but rejected by science. But further research 

 has placed it beyond all doubt that the begin- 

 nings of sex are synchronous almost with those 

 shadowings in of life. From a state marked by a 

 mere varying of the nuclear elements, a state which 

 might almost be described as one antecedent to 

 sex, the sex-distinction slowly gathers definition, 

 and passing through an infinite variety of forms, 

 and with countless shades of emphasis, reaches at 

 last the climax of separateness which is observed 

 among birds and mammals. Often, even in the 

 Metazoa, this separateness is outwardly obscured, as 

 in star-fishes and reptiles ; often it is matter of 

 common observation ; while sometimes it is carried 

 to such a pitch of specialization that only the 

 naturalist identifies the two wholly unlike creatures 

 as male and female. Through the whole wide field 

 of Nature then this gulf is fixed. Each page of 

 the million-leaved Book of Species must be as it 

 were split in two, the one side for the male, the 

 other for the female. Classification naturally takes 

 little note of this distinction ; but it is funda- 

 mental. Unlikenesses between like things are 

 more significant than unlikenesses of unlike things. 

 And the unlikenesses between male and female are 

 never small, and almost always great. Though the 

 fundamental difference is internal the external form 



