GERMINATION AND HISTOLOGY OF WELWITSCHIA MIRABILIS. 23 
In longitudinal sections the epidermis does not appear as 
a regular layer covering the apical cone. Whether this 
cone does develop further or not I have no evidence to 
prove. In the young plants preserved in Kew there are, 
however, to be seen two conical structures lying between 
the plumular leaves. It must for the present remain un- 
decided what the morphological value of these is. 
In the structure of the cotyledons there is little of im- 
portance to notice. The arrangement of tissues is nearly 
the same on both sides of the leaf. Both the epidermal 
layers of the upper and under surface have stomata; 
beneath the epidermis is on both sides a double layer of 
pallissade cells, and between these a spongy tissue. The 
main fibro-vascular bundles show a structure similar to 
those of older leaves, though less complicated. There | 
are no spicular cells to be seen in the parenchyma of the 
cotyledons, but along their margins the cells are slightly 
thickened in a colleuchymatous manner, 
As they pass down the hypo-cotyledonary stem the ar- 
rangement of the bundles does not change; their course 
being strictly parallel till the point is reached, where the 
feeder extends laterally into the endosperm ; here two of 
the bundles curve towards the organ. 
It was seen that the feeder “appeared externally, as a 
lateral protuberance on the hypo-cotyledonary stem. It 
remains to be decided what is its structure and morpho- 
logical value. 
A longitudinal section through a young seedling whose 
cotyledons have not yet been withdrawn from the seed, 
may be cut, so as to include the median plane of the feeder, 
as well as the axis of the embryo. Figure 18 represents 
such a section taken from a seed, which had been sown 
flat. The dark lines here indicate the course of the fibro- 
vascular bundles. The position of the feeder is seen to be 
opposite the swelling of the collar, and this marks the 
place, which it holds relatively to the matureembyro. From. 
the hypo-cotyledonary stem the epidermal layer may be 
followed up to the apex of the feeder, which it covers; the 
epidermal cells, however, alter their form, being, as the 
apex is approached, more and more drawn out in the 
direction parallel to the axis of the feeder. A like change 
may be tracedin the parenchymatous cortical tissue. The cells 
of the latter are, in the hypo-cotyledonary stem, arranged in 
regular longitudinal rows ; these may be followed, as they 
curve into the body of the feeder. Here, however, their 
regularity has been disturbed by divisions in directions 
