ADULT ANATOMY OF WELWITSCHIA MIRABILIS. 343 
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in the hypocotyl *. Some suggestions of this arrangement are already visible at W, 
text-fig. 3, I. 
The Vascular Supply of the Ridges—In older seedlings this growing complexity 
makes it difficult to distinguish the four original cotyledonary bundles, This difficulty 
is increased and the distribution of the bundles made more irregular by the entrance of 
à large number of bundles from the ridges. It remains to draw attention to the 
presence of a few of these even in the young seedling just described. 
At X, text-fig. 3, F, several bundles are seen ending freely in the pith. When these 
. are traced upwards they tend to form two groups on the periphery of the hypocotyle- 
donary vascular cylinder. ‘These groups become (r, text-fig. 3, G) distinctly concentric, 
and their concentric arrangement is later still more obvious as they are traced upwards 
to their termination at the base of the developing outer ridge t (L, text-fig. 3). i 
Some of the bundles seen in the pith in F, G, H, text-fig. 3, end freely upwards ; at their 
termination they are represented only by a few meristematic divisions (v, text-fig. 3, I, K). 
They probably represent the rudimentary vascular supply of the stem apex and cotyle- 
donary buds $; in older seedlings no bundles were seen at the apex of the plant, but 
they were all prolonged into the cotyledonary buds. In a seedling in which the cotyle- 
donary buds were very unequally developed (Pl. 34. fig. 6) the bundle-supply first 
appeared much lower down on one side than on the other. zd 
In the older seedlines the elliptical series of numerous bundles $ then supplying 2. 
ridge (text-fig. 4) becomes secondarily connected with the bundles in the hypocoty i 
half of the bundles from the ridge joining one pole of the hypocotyledonary EE an 
half joining the other pole. Bower's material did not make it possible for him to pus 
the development and origin of the ridge-bundles, and he does not appear to have clearly 
: i . 66, fig. 35. 
* Cf. concentric rings in the Cycadacew, Worsdell, 1896 &o., and in Cycadella, rra P i : tyl of the 
T A similar concentric series of bundles was followed downwards and found to end freely in ypovo i 
ey older seedling shown in Pl, 34. fig. 6. 
+ Bower, IT. p, 581, $ Ante, p. 338. 
8 3E 
ECOND SERIES.— BOTANY, VOL. VII. 
