21 
A natomy of the Ophioglossaceae. III. 
cortex on the right-hand side, and has left an open leaf-gap. The branch 
stands over the preceding leaf-gap which is now closed. The portion of 
the branch shown has presumably been laid down by the activity of its 
proper apex, and has adjusted itself to the position in which the parent 
fragment lay in the soil. The parent fragment had apparently been 
inverted in the soil, for while U indicates its upper surface, and L its lower 
surface, u. and /. indicate the upper and lower sides of the branch. The 
attachment of the stele of the first root of the branch is seen at r.\ while 
l.t . 1 indicates by a dotted line the course of the first leaf-trace, which was 
actually shown in a neighbouring section, 
of its own in the outer part of its course 
through the cortex of the main rhizome, 
but in the more basal portion the limit is 
indistinct. 
The sections represented in Text- 
fig. 6 , taken together with Photos 27- 
29 on PI. II, will serve to illustrate the 
relation between the branch and the 
parent rhizome in following the series from 
behind forwards. Text-fig. 6, A, shows 
the gap, left by the leaf-trace subtending 
the branch, beginning to narrow ; the 
leaf-trace has already left the cortex. 
The xylem tube is seen to consist of 
inner and outer xylem, and of accessory 
xylem, the latter being strongly de¬ 
veloped at the sides of the leaf-gap. 
The position of the nascent leaf-trace on 
the other side of the median line is evi¬ 
dent, the trace still forming part of the 
stelar tube; accessory tracheides are 
wanting immediately outside the trace. 
The accessory xylem has been present 
around the stele since the first indication of the leaf-trace which subtended 
the gap now beginning to close. 
The condition a little further forward is shown in Text-fig. 6 , B, in 
which the nascent leaf-trace is more distinct, the closure of the leaf-gap has 
advanced, and the accessory xylem is very strongly developed at its margins. 
The inner xylem is also well developed at the edges of the gap. In the next 
section (Text-fig. 6, c) the endarch leaf-trace is separating, and on the left- 
hand side the gap in the xylem has become closed. The inner xylem is of 
considerable thickness in this region, and has evidently taken a main part in 
closing the gap. Whether the tracheides in the position marked ? are to be 
The branch has acquired a cortex 
Text-fig. 5. Transverse section of 
the rhizome bearing the second branch, to 
show the relative position taken up by the 
main stem and the branch. Description 
in text, u, upper ; L, lower side of main 
rhizome; upper; lower side of 
branch rhizome p ; r. 1 , first root of branch ; 
l.t. 1 , line of departure of first leaf-trace 
of branch. 
