230 METAMOEPHOSES OF MAN 



formation is sufficient to exhaust the provision of the 

 cells, and of the prolific force kept in reserve. In the 

 Aphides, Medusas, Distoma, &c, it is otherwise. A 

 portion of the mass, composed of germinal cells, passes 

 unchanged into the embryo's body, and the prolific 

 power being still in play, the cells continue to mul- 

 tiply in their new abode. As soon as a sufficient 

 quantity is formed, a new being is organized, which 

 carries with it its own proportion of the cells and 

 reproductive force. But, in consequence of the repe- 

 tition of this process, the prolific power becomes 

 eventually exhausted, and then only the inter- 

 vention of the two sexes is necessary, in order to 

 renew it. 



All animal reproduction is the result of a single act 

 of fecundation, brought about by the connection of the 

 male and female, the first giving to the fundamental 

 element, which is supplied by the second, the power 

 of reproducing itself, during a period which varies 

 according to the species. In reproduction by ova this 

 force is exhausted during a single intercommunication, 

 and must be renewed at each generation. In par- 

 thenogenesis, this force is transmitted through several 

 generations, together with the material elements, pro- 

 ceeding* from the first germinal cell. In both cases 

 the latter is the starting-point. In it is accumulated, 

 even at first, that prolific force which sets agoing the 

 more or less permanent but always identical phe- 

 nomena. Consequently, parthenogenetic reproduction 

 differs only in point of accessory circumstances from 

 ovarian reproduction. Fundamentally, they are one 

 and the same phenomenon. 



This is a brief sketch of Professor Owen's theory. 



