of Lepidostrobus Brownii , Schpr. 339 
It has been already stated that the bundles of the leaf-trace 
are given off from the projecting teeth of the central stele, 
such as that shown in the middle of Fig. 3 A. 
Our next study will be to follow such a bundle on its 
course outwards, and consider its structure and its relations 
to the surrounding tissues. The general course pursued by 
the leaf-trace in this cone is shown in Fig. 2 to be obliquely 
upwards from the point of origin. The band of firm ground- 
tissue which surrounds the central stele is first traversed ; 
here the bundle shows such structure as is seen in the 
transverse section in Fig. 4 — it is of considerable bulk (though 
this appears to be variable, Fig. 4 B ) and consists of a well- 
defined mass of xylem (xy) directed towards the centre of 
the axis, and of less clearly defined tissue, probably phloem, 
which is on the peripheral side (ph. Fig. 4 A) ; the whole is 
surrounded by an ill-defined sheath of thin-walled cells, in 
which the characters of endodermis or pericycle cannot be 
recognized with any degree of certainty. It is to be specially 
noted that many of the cells of this sheath have divided 
so as to duplicate the sheath (cells marked x> Figs. 4 A and 
4 Z>), a point which may frequently be observed round similar 
bundles of Lycopodium and Tmesipteris . It has been found 
impossible to recognize the protoxylem with certainty: in 
the wood of this bundle (Fig. 4) there is no clear indication 
of it, either by size or marking of the trachcides ; nor does 
examination of the longitudinal sections (Fig. 9) materially 
help, beyond the fact that the tracheides on the central 
limit have a slightly closer thickening than those lying 
further outwards ; accordingly it is impossible to make 
a definite statement as to the number of initial points of 
development of the wood ; it may, however, be remarked 
that such a bundle as Fig. 4 A, B, which is most excellently 
preserved, gives no support to the view that the bundle 
is diarch, as has been stated as a distinctive character for 
Lepidodendron, though (as I think) on slender evidence, by 
Renault 1 ; still less does it appear that the bundle is of 
1 Cours de Bot. Foss., Ill, p. n. 
A a 
