CRYPTOGAMS 



351 



bryophytes, and may be represented by the same formula. 

 The chief difference is in the relatively much greater im- 

 portance of the sporophyte, which may be expressed by 

 putting it first : 



oos "S > o 



^o >G etc. 



But some of the pteridophytes of which the Selaginella 

 offers a conspicuous example have differentiated their 



505 



506 



504 507 508 



FIGS. 504-508. A kind of pteridophyte (Selaginella martensii) with its organs of 

 fructification: 504, a fruiting branch ; 505, a microsporophyll with a microsporan- 

 gium, showing microspores through a rupture in the wall ; 506, a megasporophyll 

 with a megasporangium ; 507, megaspores ; 508, microspores. (From COULTER'S 

 " Plant Structures.") 



