SIMPLEST FORMS OF GENERATIVE PROCESS. 



435 



rence being, that in the latter the fission commences ill the nucleus, each 

 half of which seems to draw around it a portion of the contents of the 

 cell, whilst in the former the fission shows itself at once in the entire 

 endochrome, there being no distinct nucleus (Fig. 132). Now although 

 the effect of this operation is to produce a great number of new cells, 

 yet it cannot be truly considered as an act of Generation ; for it is ob- 

 viously analogous to that multiplication of the component cells, which 

 takes place as a part of every process of development in the most com- 

 plex organisms ; the only difference being, that the new cells are here 

 in great degree independent one of another, so as to be able to maintain 

 their existence when isolated ; whilst among the higher tribes, there is 

 so close a relation of mutual dependence between the component cells, 

 that they cannot continue to live if separated from one another. And 

 we shall hereafter see, that the early development of the embryonic 



Fig. 133. 





Successive stages of development of simpler Algae : A, individual cells of Protococcus viridis ; B, c, clusters 

 formed by their multiplication ; D, filament of Schizogonium murale ; E, a similar filament, subdividing late- 

 rally, which constitutes the early form of the Ulvacece; F, G, portions of the expanded thallus of Ulvafurfu- 

 racea, formed by the continuance of the same process of transverse subdivision. 



mass, even in the highest Animals, presents phenomena in all respects 

 comparable to this multiplication of the simplest Cellular Plants by 

 successional subdivision ( 805) ; all the descendants of the original cell, 

 however, here remaining in mutual apposition, and concurring to make 

 up what is commonly designated as a single individual, whilst in the 



