The Occurrence of a Cavity filled with Hairs in 
the Stem of a Species of Cucurbit. 
BY 
J. W. BEWS, M.A, BSc. 
With Plate XXV. 
The way in which the Hair-Cavity arises. 
The stem of this species of Cucurbit, like most of those which 
I have examined, is a hollow one. The nodes are solid, but the 
central cavity of the stem extends the whole length of the inter- 
node. The cells surrounding this ordinary central cavity differ 
in no way from the other parenchymatous cells of the stem. 
They are fairly large thin-walled cells, and are not arranged in 
any definite manner around the central hollow. 
The vascular bundles are of the bicollateral type, with large 
vasa in the centre, phloem on the outside and also on the inside. 
The stem is pentagonal in outline, with five prominent ridges. 
The whole surface of the plant is covered with hairs (Fig. 4). 
In one part of the stem certain cells form a projection into the 
central cavity. These projecting cells are at once marked off from 
the other surrounding cells in being smaller and full of cell- 
content. The projection appears to have originated as a single 
cell, and afterwards, in the centre of the projection, there is 
meristematic tissue. 
As this structure is followed along the stem, it increases in 
size till it gradually fills up the whole of the central cavity. 
But before it has altogether done so, in the centre of the pro- 
jecting portion, that is to say, in the centre of the meristematic 
tissue, another cavity arises, and this is the cavity which contains 
the hairs. 
(Notes, R.B.G., Edin., No. XIX., April 1908.} 
