THE SPORE-PRODUCING MEMBERS 695 
that the spore-producing members, whether sporangia or sporangiophores, 
have been susceptible of considerable differences of position in the radial 
plane, and that in this the sporangia show a. parallelism with the sporangio- 
phores which it is important to recognise in parts which are identical in 
their function. ; 
The position of the leaves relatively to the spore-producing members 
in strobiloid forms is usually, but not constantly, a subtending one: there 
is reason to believe that a constant relation was a usual condition in 
primitive forms, while the exceptions may be held to be secondary in their 
origin. In the Lycopodiales the subtending relation of leaf to sporangium is 
Diagrams illustrating the relation of spore-producing members and sporophylls or 
bracts, and the results of their respective ee as seen in surface view from the 
adaxial side. A=Lycopodium. B=IJsoetes. C=Lepidostrobus. The dots in B and C 
show the trabeculae. D=Tmesipteris. H= Peed F=Palacostachya. G=Calamo- 
stachys Binneyana. H=Calamostachys germanica. I=Sphenophyllum majzus. 
J=Sphenophyllum Dawsoni. K=Cheirostrobus. L=Ophioglossum.  M=abnormal 
case of Ophioglossum (see Fig. 359 J, K). N=Helminthostachys. 
A B 
Fic. 361. 
constant (Fig. 361 A, B, C), as it is also in those of Sphenophyllales wherever 
there is a single sporangiophore to each bract-leaf (Fig. 361 p, E.1), but 
it is departed from in those cases where more than one is associated 
with each bract (S. Dawsont, Rémeri, p. 402, Fig: 361 J). The con- 
dition seen in Cvhecrostrobus strongly suggests chorisis of both bract and 
sporangiophore (Fig. 361), and their mode of insertion upon the bract- 
whorl in other species of Sphenophyllum above quoted indicates it as 
probable that some similar chorisis of the sporangiophores has been 
effective in them also (Fig. 361 J). In the Equisetales the relation is 
generally less exact: it seems still uncertain whether or not the sporangio- 
phores were actually subtended by the bracts in /alaeostachya (Fig. 
361 F):! in Calamostachys they may be somewhat irregularly subtended by 
1See Hickling, 4c., pp. 372, 377. 
