of Vascular Strands in Angiopteris evecta . 379 
Sooner or. later, however, commissures of an attenuated form 
appear in this plant also, and cross the intervening parenchyma 
(Fig. 7) exactly as in Angiopteris. We unfortunately had no 
plants old enough to enable us to follow out fully the later 
developments. The roots come off, so far as we have seen, 
from the outer surface of the siphonostele, and are even less 
regularly related to the leaves than is the case in Angiopteris. 
The leaf-traces are at first single, but those subsequently 
formed fork once whilst still in the stem cortex, and the 
dichotomy, as in Angiopteris , extends farther backward in the 
successively produced leaves, till it is obvious at their first 
origin at the base of the foliar gap. 
The most striking feature of difference between Angiopteris 
and Marattia at this stage lies in the large diameter of the 
siphonostele, and the very large foliar gaps which are very 
characteristic of the latter genus. 
Kaulfussia. The vascular skeleton has been excellently 
elucidated by Kuhn *, and our investigations largely confirm 
his results. Unfortunately we wete unable to secure any 
young plants of this genus, so we are not in a position to 
trace the ontogenetic evolution of the vascular strands. As 
might have been anticipated from its markedly dorsiventral 
habit and comparatively thin rhizome, the vascular system of 
Kaulfussia is much simpler than that of the other two genera, 
but it also exhibits features of interest which serve to illustrate 
some points in the anatomy of the preceding ferns. The 
vascular strands in the mature stem consist of an outer net- 
work from which the leaf-traces are given off on the upper 
side, and the greater number of the roots on the lower. This 
network encloses a parenchyma in which is embedded an 
axile vascular strand which pursues an undulating course, 
bending first to the upper and then to the lower face of the 
reticulated cylinder, with which it is alternately connected 
in the way described by Kuhn. We regard this as certainly 
representing the commissural strand which occupies an exactly 
analogous position in both Angiopteris and Marattia , whilst 
1 Loc. cit. 
C C % 
