n ft 
00° 
Wer nham .— The Morphology of 
. 
many of the sections they are seen to be undoubtedly mesarch. The 
wood-elements are thus confined in this specimen to the stalk of the tuber; 
the body is entirely destitute of vascular tissue. 
One or two notable differences were observed, however, in the second 
specimen examined: first, the bundle of the young tuber divided into two 
strands, which united further up, before joining the vascular system of the 
stem; second, a ring, more or less continuous, of somewhat degraded 
xylem was observed surrounding the central merismatic tissue of the young 
tuber. This ring, however, disappears before the stalk-region of the tuber 
is reached. 
In the second specimen, moreover, three tubers appeared in section; one 
corresponding to the younger 
V*- 0- tuber, and two older ones— 
and this corroborates Thomas’s 
statement in the Proc. Roy. 
Soc., xix, p. 285. 
These differences in the 
two specimens will be referred 
to later. 
The two sections—old and 
young tubers—are now seen to 
approximate as we follow the 
sections successively upwards; 
the older begins to be cut some¬ 
what obliquely, and two root- 
traces appear in longitudinal 
section. The latter evidently 
bend up rapidly at this stage 
(Fig. 3), as they are seen, three 
in number, in clear transverse section shortly after the two tuber sections 
have merged. The roots are distinctly monarch, and resemble Stigmarian 
rootlets closely; a well-marked endodermis is present, and the ground 
tissue presents a highly lacunar appearance. 
Further up, these root-traces are found somewhat nearer the centre of 
the section, having become connected laterally by other wood-elements 
running, at first, almost horizontally; at this point we are entering the 
lower part of the compressed stem. 
2. The Stem . Proceeding as before with the sections in ascending 
order, leaf-traces begin to be r pinched off’ the stele thus formed, and these 
leaf-traces occupy the same relative positions previously taken by the 
root-traces. Leaf- and root-traces are thus continuous, a fact pointed out 
by Bower twenty-five years ago. The mode of exit of these leaf-traces is 
that typical of the Lycopsida, there being no disturbance of the stele. The 
Fig. 5. Transverse section, lower part of stem. 
Parenchyma left blank, xylem black. The young tuber 
strand, y.t.s ., has joined the main stele ( s.s .). Five leaf- 
traces appear, two with included protoxylem cavities 
U>xc). 
