GERMINATION AND HISTOLOGY OF WELWITSCHIA MIRABILIS, 19 
The form and size of the cotyledons may be gathered from 
the figures 7 and 8. While still enclosed in the seed they 
are yellowish orange; they maintain this colour some time 
after appearing above the soil. Finally, they become green, 
and in this condition they remain persistent for a consider- 
able time; they are at all times glabrous and have entire 
margins. Each cotyledon has two main central bundles, 
which run parallel to one another, and two lateral ones 
parallel to these. Each of the four gives off smaller lateral 
branches, which anastomose freely. 1 have observed no 
axillary buds in the axils of the cotyledons as in Ephedra. 
The hypo-cotyledonary stem is variable in length, from 
13 to 23 inches. It is compressed in the plane of the cotyle- 
dons, and is slightly swollen just below the point of junction 
with them. The root, which is a direct elongation of the 
radicle, has, in the plants already grown, attained a length 
of 4 ot 5 inches, without a single lateral branch, with the 
exception of one case where the apex of the root had been 
injured ; here a lateral root had been formed. 
‘I'he undoubted presence of a pair of plumular leaves in 
Welwitschia suggested a comparison of the young seedlings 
with the smallest specimens, preserved in the Kew museums. 
The result is the discovery of evident traces of the existence 
of leaves, previous to the large expanded pair, which are 
characteristic of the plant. Fig. 10 represents the apex of 
the youngest plant in the Kew collections, as seen from 
above. Here may be seen, protruding from the stem below 
the main pair of leaves, the ragged remains of fibro-vascular 
bundles, which run directly into the tissues of the stem. 
These, from their position and apparent course, point to the 
existence of a previous pair of leaves, which have decussated 
with the present pair, but which have rotted off. Traces of 
these may be found in even older specimens than the one 
figured, so that, not from one plant only, but from several 
may be deduced the conclusion, that the main leaves of 
Welwitschia are not persistent cotyledons, but leaves de- 
rived from the plumule. Hitherto we have only seen two 
plumular leaves formed; we may, therefore, reasonably 
conjecture that those plumular leaves are persistent as the 
typical pair of leaves of Welwitschia. ‘The absolute proof 
of this will, we may hope, be afforded by the successful 
growth of the seedlings now living at Kew.! 
1 Concerning the morphological value of the structures seen between 
the leaves of the plant, represented in fig. 10, I am not at present in a 
position to make any statement. 
