GENERAL MORPHOLOGY 445 
the balance which may subsist between the vegetative and sporangial 
development (Fig. 239 0, 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, 
Fic. 244. 
A, B, Ophioglossum palmatum, lL. A=a single fertile spike with sporangia still 
closed. #=part of the same with sporangia ruptured. C-E=SBotrychinm Lunaria, 
Sw. C=a fertile spike. D=a branch of the same with ruptured sporangia, seen from 
within. &=the same seen from without. #, G=Helminthostachys zeylanica. Hook. 
F=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. Pflanzenfam. 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 Botrychium, but creeping and dorsiventral in 
