236 METAMORPHOSES OF MAN 



in that ovum ; they are but the mediate offspring of 

 their parents. This is the fundamental distinction 

 between geneagenesis and metamorphosis. 



Van Beneden/s mode of view is more modest than 

 Steenstrup's, Owen's, or Leuckart's. The Belgian 

 naturalist has not pretended to explain the essential 

 character of the phenomenon, but he has been 

 especially impressed by the fact that certain species 

 of animals are reproduced by a single process, whilst 

 others are multiplied simultaneously by two different 

 means. Hence he divides the animal kingdom into 

 two classes, — monogenetic and digenetic. From this is 

 derived the term digenesis, applied to the entire series 

 of reproductive phenomena which occur without the 

 intervention of the sexes. 



To those who fully coincide with the author's 

 views, and desire to go no farther, this term seems 

 well conceived. It conveys a fact apart from all 

 hypotheses ; but, on the one hand, its only signifi- 

 cation is derived from its opposition to the term 

 mono genesis, which Van Beneden applies to ordinary 

 reproduction ; and, on the other, it does not seem to 

 me to indicate sufficiently the prominent character- 

 istics of the order of phenomena to which it refers : 

 viz., the production of several types, and of an 

 indefinite number of individualities, from a single 

 primitive ovum. 



This remark applies with equal intensity to the 

 other expressions to which I have referred. It is for 

 this reason that I propose to substitute the term 

 geneagenesis, which, to my mind, is sufficiently ex- 

 plicit, and which only conveys a fact apart from all 

 theoretical considerations . 



