260 



SEEDLESS PLANTS 



unless it had been of some benefit to the plants practicing 

 it. The chief advantage seems to be in more rapid mul- 

 tiplication and consequently better chance to propagate the 

 species. Only one plant is produced by each oospore, and 

 if this were a gametophyte with its limited number of 

 archegonia, multiplication would be slow; but the sporo- 

 phyte with its millions of spores, each capable of produc- 

 ing a new individual, enables the species to multiply 

 indefinitely. On the other hand, the interposition of a 

 gametophyte, or sexual generation, secures the introduc- 



495-499- A kind of pteridophyte (Selaginella martensii) with its organs of 

 fructification : 495, a fruiting branch ; 496, a microsporophyll with a microsporan- 

 gium, showing microspores through a rupture in the wall ; 497, a megasporophyll 

 with a megasporangium ; 498, megaspores; 499, microspores (from COULTER'S 

 " Plant Structures"). 



