SPORE-PRODUCING MEMBERS 447 
fertile condition of the leaf is normally the rule in the family; but that 
the fertile spike of the Ophioglossaceae behaves like the sporangiophore of 
the Psilotaceae, or the sporangium of Jscetes or Lycopodium in the matter 
of its abortion: this is complete in some leaves, while in others a vestigial 
structure remains to show what has occurred. Further, though their 
tendency towards a monophyllous habit may make such a comparison less 
obvious, the Ophioglossaceae show essentially a “ Sedago” condition of the 
shoot, that is, an imperfect differentiation of the vegetative and reproductive 
functions. Their condition would, in fact, be consistent with a strobiloid 
origin, modified in further development by enlargement of the appendages, 
all of which were originally fertile. This matter 
will be referred to again in connection with the 
early appearance of the fertile spike in the 
young seedling plant. 
SPORE-PRODUCING MEMBERS. 
The development of the fertile spike has been 
traced in Ophioglossum from its first beginnings.! 
The leaf itself originates very close to the initial 
cell of the deeply depressed apex of the axis. 
The sheathing stipule which envelopes the growing 
point as well as all the later leaves, is formed 
early: the spike appears above it in a median 
position on the adaxial face of the leaf, but near BGs 245: 
to its base (Fig. 245). The outgrowth is at first Gee ee 
bluntly rounded, but it soon becomes more _ median section of a young leaf, with 
the spike (sf) arising about half-way 
acute and turned upwards: it consists of several up its adaxial face. The upper 
: . drawing shows a rather older leaf in 
cells, and of these the uppermost, which 1s frontalview. x35. 
already the largest (x in the Figs. 246 4, B, C, B), 
undergoes further segmentation with some degree of regularity: its 
segments go to form the bulk of the free portion of the spike. The 
form of the initial cell is that of an irregular four-sided pyramid, but in 
some cases at least its identity is soon lost, and the type of construction 
passes over to that with four initials (Fig. 246 F, G). As a consequence 
of further subdivisions, whichever be the type of the initial segmen- 
tation, the spike comes to be composed of four quarters, separated 
by walls at right angles, as seen in the transverse section: its form 
is that of an elongated cone, slightly flattened on its adaxial and 
abaxial sides. Sections of it, transverse, radial, and tangential, are shown 
in Figs. 247 a-D: from these it appears that a special band of cells, the 
sporangiogenic band, runs along the lateral margins of the slightly flattened 
1The account here given is condensed from the full statement (S¢udzes, ii., pp. 10-27), 
where the literature is quoted. The development has been worked out for three species : 
O. vulgatum, reticulatum, and pendulum. 
