214 THE NATURE AND ORIGIN OF LIFE 



incomplete elements of the two complementary types. Such 

 an individual is called hermaphrodite and the notion of 

 individual sex, which arises from the study of the higher 

 animals, gives way to the notion of histological or genital 

 sex. There are no longer a male and a female animal, but 

 male and female reproductive elements produced by one 

 and the same animal. 



The further our investigations go the more we verify the 

 generality of the sexual process of reproduction. A prudent 

 biologist nowadays would never dare to assert that there 

 is a single animal or vegetable species in which the sexual 

 processus is wanting. Now such a generality of sexual 

 processus makes us think that it must have some relation 

 with a fundamental particularity of living substance. 



There are, however, many cases in which we see the 

 multiplication of an isolated cell coming from a cellular 

 agglomeration that has to be considered as a perfect indi- 

 vidual. But even where such parthenogenesis is possible, 1 

 we generally see the sexual processus properly so called 

 put in an appearance from time to time. An example is 

 found in certain plant-lice which, throughout the fair 

 season, reproduce by parthenogenesis and, when cold 

 weather comes, take up again normal sexual reproduction. 



The possibility of the two modes of reproduction, sexual 

 and parthenogenetic, along with the extraordinary generality 

 of the sexual processus, naturally gives rise to the idea that 

 sexuality a fundamental particularity of living substance- 

 must exist in all vital acts, while manifesting itself only 

 in certain cases in the form of cellular sexuality. 



In other words, the notion of sexuality, first derived from 

 observing the higher animals and then from the study of 

 the reproductive elements of living beings, might be trans- 

 1 Parthenogenesis, from the Greek for virginal conception. 



