GENERAL MORPHOLOGY 



445 



the balance which may subsist between the vegetative and sporangial 

 ' development (Fig. 239 o, P). Such changes are in line with those 

 observed in other Ophioglossaceae, and will with them have to be considered 

 in relation to general questions below. 



It is easy thus to arrange the Ophioglossaceae in sequence, starting from 

 simple beginnings and proceeding to those which show greater complexity, 



A 



FIG. 244. 



A. B, Ophioglossutn paiinatuHi, L. Az. single fertile spike with sporangia still 

 closed. B part of the same with sporangia ruptured. C-E^Botryckium Lunaria, 

 Sw. C = a fertile spike. Z> = a branch of the same with ruptured sporangia, seen from 

 within. . = the same seen from without. F, G = Helminthostachys zeylanica. Hook, 

 /^sterile and fertile regions of the leaf. G = branch of the latter with a group of spor- 

 angia, and at the apex the lamina-like terminals of the fertile appendage. (After Bitter 

 in Engler and Prantl, Nat. Pjlanzenfam. D after Luerssen. F, G after Hooker- Baker.) 



whether of the vegetative or reproductive parts. It will remain to be seen 

 whether such sequences have any probable relation to truly phyletic lines 

 when the internal structure and development have been considered, 

 together with the comparison of the details with those of other Pterido- 

 phytic types. But, meanwhile, it appears certain that the three genera 

 form a natural group : the sterile leaf and the fertile spike are homologous 

 throughout, so also is the stock, notwithstanding that it is upright and 

 radial in Ophioglossum and Botrychiuw, but creeping and dorsiventral in 



