178 MR. P. GROOM—CONTRIBUTIONS TO THE 
Apex of the Root. 
In longitudinal section the growing point of the root appears 
very like that of Zea Mays, though I could not establish the 
differentiation of the three histogens. The exocortex is very 
early differentiated. Mycelial masses occur only in the medio- 
cortex ; and starch-grains solely in the endocortex, extending 
about as near the actual root-tip as do the mycelial masses. 
Origin of the Roots. 
I saw one root developing at the base of an old root, in the 
pericycle. The roots then, sometimes at any rate, are endogenous 
in origin. I did not see the mode of development in typical 
cases, 2. e. from the rhizome. 
Histology of the Inflorescence—. Axis or Scape. 
Traced upwards, the scape tapers till it becomes thin and whip- 
like. A description will be given first of the structure of the 
scape at its full thickness, four inches above the attachment of 
roots, and considerably below the flower-bearing region. 
1. The epidermis consists of narrow longitudinally-elongated 
cells, with a cuticle on the outer walls, which are only moderately 
thick. A few shrivelled hairs remain. Here and there stomata 
are visible often with starch in their guard-cells. 
2. The cortex commences with two layers of parenchymatous 
cells with thin unmodified walls and small intercellular spaces. 
Some of the hypodermal cells form isolated raphide-mucilage 
sacs. 
3. These layers are succeeded by the general sclerenchymatous 
sheath of 3-4 layers of fibres. In iodized chloride of zinc it is 
easy to establish the fact that the small pits of these fibres are 
lined with cellulose, and the pits are further connected with one 
another by thin vertical or horizontal threads of cellulose tra- 
versing the inner surface of the wall. Thus in a surface view of 
a fibre the walls appear to have a peculiar network of cellulose 
with regular square meshes. 
4. The vascular bundles lie scattered in the parenchymatous 
ground-tissue of the stele, and there is a distinct central region 
(pith) devoid of bundles. 
Histology of the Vascular Bundles (Pl. V. fig. 2).—Each 
bundle is surrounded by a more or less imperfect sheath of 
sclerenchymatous fibres. The lignification and thickening of the 
