64 THE KIDDLE OF THE UNIVEESE. 



existence of the personality, the independent individual, 

 commences. This ontogenetic fact is supremely impor- 

 tant, for the most far-reaching conclusions may be 

 drawn from it. In the first place, we have a clear 

 perception that man, like all the other complex 

 animals, inherits all his personal characteristics, bodily 

 and mental, from his parents ; and, further, we come 

 to the momentous conclusion that the new personality 

 which arises thus can lay no claim to " immortality." 

 Hence the minute processes of conception and sexual 

 generation are of the first importance. We are, how- 

 ever, only familiar with their details since 1875, when 

 Oscar Hertwig, my pupil and fellow-traveller at that 

 time, began his researches into the impregnation of 

 the egg of the sea-urchin at Ajaccio, in Corsica. The 

 beautiful capital of the island in which Napoleon I. 

 was born in 1796 was also the spot in which 

 the mysteries of animal conception were carefully 

 studied for the first time in their most important 

 aspects. Hertwig found that the one essential element 

 in conception is the coalescence of the two sexual cells 

 and their nuclei. Only one out of the millions of 

 male ciliated cells which press round the ovum 

 penetrates to its nucleus. The nuclei of both cells, 

 of the spermatozoon and of the ovum, drawn together 

 by a mysterious force, which we take to be a chemical 

 sense-activity, related to smell, approach each other 

 and melt into one. Thus, by the sensitive perception 

 of the sexual nuclei, following upon a kind of " erotic 

 chemicotropism," a new cell is formed, which unites 

 in itself the inherited qualities of both parents; the 

 nucleus of the spermatozoon conveys the paternal 

 features, the nucleus of the ovum those of the mother, 

 to the stem-cell, from which the child is to be developed. 



