282 Bower. — Studies in the Phytogeny of the Filicales. 
Karsten’s drawings and description of the structure, so far as they go, 
accurately represent the facts (see ‘ Land Flora p. 605, and Fig. 336, where 
reference is made to the original paper). Lophosoria shows in certain 
sections a perfectly solenostelic state, the vascular ring opening in the usual 
way to give off a broad segment of the ring as a foliar strand. This is 
shown in PI. XXXIV, Fig. 10, in which it is seen that the separation of the 
strand is not effected synchronously on both sides. One margin separates as 
a rule before the other, and this is in fact usual in Ferns with a creeping axis. 
After both are clear, a wide gap is left in the solenostele, which ultimately 
closes again. Sometimes the leaf-gaps almost overlap. A case is shown 
in Fig. 9 in which in a very large axis a foliar gap is seen still open, while 
on the obliquely opposite side the solenostele is already thinning out in 
preparation for the formation of the next succeeding leaf-trace. A clear 
idea of the behaviour can be obtained by comparison of a succession of 
sections, such as those shown in Fig. 11, which are similarly orientated, and 
are ranged in succession from below upwards. Fig. 11, i, shows the 
solenostele open on the side opposite to a leaf-trace which has just come 
off ; the internal sclerotic ring has already closed, but not the stele. It 
may be noted that the leaf-trace shows the unusual state of having joined 
its margins, so as to form a complete ring ; it may be remarked, however, 
that the leaf was a stunted one, the axis being a pushing adventitious 
shoot. Fig. 11, ii, shows a point higher up, where the foliar gap is closed, 
but the stele is still thinner there than the average. On the side almost 
opposite, the stele is thinning out for the formation of the next leaf-trace, 
but it is still a complete solenostele. In the next section, Fig. 11, iii, the 
leaf-trace thus prepared for is just separating at one margin, but connected 
by the other. In Fig. 11, iv, that leaf-trace is quite separate, and it shows 
again the closing in on the adaxial side, so as to form a complete ring. In 
the last section of the series, Fig. ii, v, the solenostele has closed completely, 
though two thijiner points are seen, the one marking where the ring has 
closed after the departure of the last leaf-trace, the other showing where 
the next will come off, and this is already indicated also by the slight 
outgrowth of all the tissues on the side obliquely opposite to the preceding 
leaf. It is thus evident that the leaf-gaps do not actually overlap, though 
they may follow in rapid succession, and the structure is accordingly 
solenostelic, but with a rather compact arrangement of the leaves, which 
is specially marked where the plant has settled down to its normal 
vertical growth, with a terminal tuft of leaves. 
The validity of these results is shown by PL XXXII, Fig. K. This does 
not represent any idealized conception of the vascular system, but it is 
an accurate delineation of an actual dissection of a large axis, from which 
the cortex has been removed, and the vascular system laid bare. The 
outer surface represented in the drawing is the solenostele itself, and it 
