Ophioglossum (C heir og loss a) palmatum , L. 285 
it is necessary to be clear how complete the fusion of the marginal series is 
on the adaxial side. This is shown in Fig. 21 , a, b, from which it appears 
that all possibility of discriminating between the confluent marginal strands 
is lost. The supply to the spike is afforded by the median adaxial region 
of the flattened circle. The same is the case with O. intermedium , l but 
here the actual coalescence of the marginal strands appears to be delayed 
till the base of the spike is reached, while the proportion of the strands of 
the fertile to those of the sterile region matches the relative size of those 
parts. It may be concluded from my own drawings of O. simplex that 
the condition there is in principle the same. 2 Hence it is seen that 
the identity of the margins as marked by the vascular strands is entirely 
obliterated, while the vascular supply to the spike in Ophioderma comes off 
from the indeterminate vascular supply on the adaxial side of the petiole. 
Turning now to Cheiroglossa , in the leaf-stalks of the weaker and 
first-formed sterile leaves the margins as defined by the vascular strands 
are widely apart, which is naturally in accord with their flattened form. 
But as the plant strengthens and works up to the production of propagative 
organs the leaf-stalks become more nearly cylindrical, while the marginal 
strands come nearer together, till in the fertile leaf they constitute a com- 
plete circle (Fig. 2, I-III). Frequent fusion of strands is seen on the adaxial 
side, so that the identification of the margins by means of the strands 
is quite impossible. This obliteration of the margins takes place close to 
the leaf-base, and it is far above the point where it occurs that the fertile 
spike or spikes arise. The source of their vascular supply has been in- 
dicated for a case where there were three spikes, the lowest of them median. 3 
But fresh drawings have been made from the old sections, giving the details 
more satisfactorily (Fig. 17, 1 -IX). From these it is seen that the supply to 
the lowest spike, which was median, comes off from the adaxial region of 
the circle of strands, where the marginal characters had been completely 
obliterated by the repeated fusions during their course through the 
elongated cylindrical petiole (I, II). By the passage of the median 
strands outwards the remainder of the strands appear ranged in a semi- 
circle (III). Fig. 1 7, III-VII, shows successive steps in the separation of the 
vascular supply for the two higher spikes, which are borne right and left. 
The origin of the strands is by segregation from the margins of the semi- 
circle ; it may, however, be noted that their derivation is not by any uniform 
scheme, though the number ultimately arrived at is in each case three. 
The sections show further that at the level of separation of the spikes their 
position on the leaf was intramarginal (VII-IX). It is worthy of note as 
having some bearing on their morphological character that the number of 
1 Campbell, loc. cit., p. 153, Fig. 12. 2 loc. cit., Figs. 24-9. 
3 loc. cit., Pl. XII, Figs. 14-23. 
