374 Farmer and Hill. — Arrangement and Structure 
The minute anatomy of the vegetative organs was also 
described. 
Kuhn seems to have regarded as an essential character of 
the vascular arrangement in the stems of these plants, the 
presence of an axile strand or bundle which is surrounded by 
one or more rings of peripherally situated strands. The 
simplest condition is presented by Kaulfussia. In this Fern 
there is only a single ring of peripheral bundles. These 
anastomose with each other and give rise to the leaf-traces. 
Below the exit of the latter, the axile strand bends upwards 
and then gives off either two bundles, or a single one which 
immediately proceeds to fork, and the latter, by joining the 
peripheral ring, serve to close up the foliar gap. The axile 
strand from which they sprang then bends downwards, and 
resumes its old position nearer the ventral surface of the stem. 
Each leaf, situated obliquely to the right and left of the stem 
alternately, receives three main strands, whilst the roots 
spring from the lower strands of the dorsiventral stem. 
Kuhn regards the arrangement obtaining in Marattia as 
substantially similar to that of Kaidfussia y when allowance 
is made for the more radial character of the stem of the 
former. The young plant possesses a similar axile bundle 
situated in the middle of a ring of peripheral strands. But 
so far as we understand his account the mutual relation of 
these is not regarded as being quite alike in the two cases. 
In Marattia the axile strand is not considered as a single 
cauline bundle, but as made up of different ones at different 
levels. Thus the axile strand of one level passes to the 
periphery higher up, its (axile) place being taken by a bundle 
from the opposite side of the peripheral ring. The original 
axile strand finally passes out as one of the leaf-trace bundles. 
The closure of the foliar gap above, as in Kaulfussia , is said 
to be related to a strand which unites with the sides of the 
gap, but the details are rather more complicated. In the 
successive outer zones of bundles of older plants the gaps left 
by the exit of leaf-traces are said to be compensated in much 
the same way as stated by Mettenius. 
