696 CONCLUSION 
two (Fig. 361 G), or by three bract-leaves (Fig. 361 H): or in Archaeo- 
calamites and Lguisetum the sporangiophores may be borne quite inde- 
pendently of any bracts. It thus appears that the most usual condition 
is clearly that where the bract subtends the spore-producing member, 
whether sporangium or sporangiophore; but this arrangement is liable to 
be disturbed by chorisis of either bract or sporangiophore, or by the 
entire absence of the bract. 
These presumable fissions, which comparison indicates as having 
occurred in both sterile and fertile parts, deserve attention: it appears 
that they may affect either class of parts separately or both together. 
In the simple condition of the Lycopodiales fissions of the appendages 
are very rare; but examples have been recorded where two sporangia 
appear side by side in Zycopodium,! and an occasional case of a bifid’ 
protophyll has been observed in the young plant of Lycopedium and 
of Phylloglossum ;? but these characters have never become permanent 
for any race of Lycopods. In the Equisetales the result of fission is seen 
frequently in the bracts (Fig. 361 G, H), though not in the sporangiophores 
of the ancient types; but in the modern genus Lgwudsetwm fission of 
sporangiophores appears to have been effective. An examination of the 
very numerous sporangiophores of L£guisetum maximum shows frequent 
cohesion of their stalks, while a comparison of the simpler species, such 
as £. palustre and of the Calamarians, leaves little doubt that with 
enlargement fission of the appendages has occurred (Fig. 195). Forking 
is a marked feature of the leaves in the Sphenophyllales (Fig. 361 1), but 
not necessarily accompanied by fission of the sporangiophore. In some 
forms, but not in all, there is, however, such a collocation of the sporangio- 
phores, in number and position as well as in vascular connection, as would 
indicate that an increase by fission has occurred to produce them: but 
this may occur independently of any fission of the bract (Fig. 361 3). In the 
very complex cone of Chezrostrobus it is highly probable that fission has 
been effective in both parts, as the vascular connections appear to indicate 
(Fig. 361 Kk). Lastly, the branching of leaf and spike, described at length 
for the Ophioglossaceae (pp. 435-439), can best be understood as the 
consequence of similar progressive fissions (Fig. 361 1, M,N). It thus 
appears that fission has probably been a frequent feature in producing 
the condition of the appendages in the strobili actually observed in the 
more complex sporangiophoric types, and that such fission may occur 
independently in either sporophylls or spore-producing members, or 
coincidently in both. On the other hand, the condition usual in the 
Lycopods may be regarded as a type which has remained on the simpler 
basis without fission.? 
1 Annals of Botany, vol. xvii., p. 278. 
2Treub, Ann. Jard. Buit., vol. viii., taf. v., fig. 2A. 
3 By the term “‘fission,” as here used, is to be understood a chorisis which dates 
from the initiation of the primordium: the fission is not a branching of a part which is 
