289 
Ophioglossum (C heir og loss a) palmattim , L. 
Some indication of a like process is seen in the Sphenophyllales, while it is 
not going too far to trace a distant parallel in the spread of the sori over 
the enlarged leaf surface in many phyla of Ferns. The following are the 
facts and considerations which make me think that we may find in duplica- 
tion in its widest sense, or pleiogeny } as it might better be termed, the 
correct interpretation of the peculiarities of O. palmattim . 
I. Frequent branched conditions of the fertile spike occur in O. palma- 
tum . This is especially common in specimens where the number of spikes 
is large (‘ Studies,’ ii, Figs. 120-9). The details in some of the spikes near 
the margin in O. palmatum are closely similar to the branchings observed 
in O. pendulum, in cases where the single though branched spike is inserted 
in a median position (‘ Studies,’ ii, Figs. 131, 132). Thus the branching is not 
a feature of the median spike only, nor is the branching always a simple 
bifurcation, as Dr. Chrysler’s interpretation would demand. 
II. A parallelism has been traced between the number of the lobes of 
the sterile leaf and the number of the spikes in O. palmatum, showing that 
the number of the fertile spikes bears a general relation to the nutritive 
leaf area. As the plant grows stronger the higher complexity in both 
regions is attained. There are signs of a like though less exact parallelism 
in O. pendulum . These facts readily accord with a theory of pleiogeny. 
III. Certain specimens have been described, such as those shown in 
‘ Studies ’, ii, Figs. 120, 121, which are difficult to harmonize with any pinna- 
theory, though they fall in readily enough with a theory of pleiogeny. They 
show certain of the higher-seated spikes in an approximately median 
position, nearer, in fact, to the centre than others which are almost at the 
same level but more nearly marginal in their insertion. The vascular con- 
nexions of these have not been examined by sections, but the specimens are 
often sufficiently transparent to give opportunity for tracing them, and from 
such evidence it seems highly improbable that they would turn out to be 
constantly marginal like the rest. 
IV. The superficial origin of the spikes upon the adaxial face of the 
leaf is now demonstrated developmentally, and even the later spikes of the 
leaf have, so far as observed, an intramarginal insertion (Figs. 8, 9, 13, 15), 
while numerous cases can be quoted where the spikes show no regular 
alternate arrangement as pinnae usually do. 
V. The identity of the margins of the leaf, so far as these are defined 
by the vascular strands, is entirely merged by the repeated fusions of the 
strands on the adaxial face of the elongated petiole. It is, therefore, 
a question how far the marginal strands above the first spike really repre- 
sent the original (phyletic) margins to which normal pinnae might be referred. 
VI. Dr. Chrysler, following and extending the observations of Bertrand 
and Cornaille, has shown that marginal vascular origin is not a necessary 
1 See note explaining this term, p. 296. 
