Bower . — Studies in the Phytogeny of the Fill cates. 403 
Text-fig. 15. Transverse section 
of the stock of Doodia maxima , J. Sm. 
It shows the inconstancy of the strands 
of the leaf-trace, x 3. 
latter come off at first as two strands, one or both of which very soon 
abstrict to form one or more smaller strands. The vascular supply thus 
passes into the leaf, sometimes as three 
strands, sometimes as four — a condition 
which may be matched in species of Blech- 
num of medium size. But in Woodwardia 
radicans the case is more complicated. 
A section of a stock of relatively small size 
is shown in Text-fig. 16. Numerous root- 
traces are given off, and frequently without 
that definite relation to the foliar gap and 
leaf-trace which is so characteristic of 
Blechnum. The point of special interest 
is, however, the mode of origin of the 
leaf-trace. The foliar gap opens widely, 
and four of them are identified by numbers 
in the section : 1 shows a gap cut near 
to its base ; a root-trace is being 
given off from one of the meristeles, 
but the leaf-trace has not yet ap- 
peared ; 2 is traversed at a higher 
point, and already three small strands 
have arisen which will form the cen- 
tral region of the leaf-supply, but not 
the larger lateral strands ; a root- 
trace is passing off from one of the 
meristeles ; 3 shows the leaf-gap 
at its widest, and the larger lateral 
strands are detaching themselves 
from the meristeles which bound it, 
while four smaller strands, which had 
clearly originated before and sepa- 
rately from them, are ranged so as 
to form the horseshoe-like series ; 
4 shows the leaf-trace completed, 
and the gap narrowing. It is thus 
seen that the origin of the leaf-trace 
in W. radicans differs from the plan 
which is usual in Blechnum. There, 
the trace consists of two strands, or 
more, but the smaller median strands 
are derived by abstriction from the larger, 
originate independently from the foliar gap. This indicates for Woodwardia 
Text-fig. 16. Transverse section of the 
stock of Woodwardia radicans (L.), Sm. The 
leaf-gaps are numbered in their succession from 
below : at gaps 2 and 3 the median strands 
of the trace are detached before the lateral 
strands have separated from the meristeles of the 
axis, x 3. 
Here, the median strands 
