236 Boodle and WorsdelL — On the 
a wedge-like shape. The point of the wedge, containing the 
xylem, is directed towards the centre of the stem, the orienta- 
tion of these bundles being normal. The phloem sometimes 
has a few scierenchymatous elements on its outer limit 
(Figs. 1 , 2, 3 , 4). 
On each side of the cortical bundle, thick-walled elements 
occur which are specially distinguished from the surrounding 
cells by their lignified, pitted walls, and by absence of proto- 
plasmic contents. As seen in different sections they vary in 
shape and size : when large, they are rendered conspicuous 
by their numerous simple pits, and their irregular or angular, 
but parenchymatous shape ; the smaller ones are often 
difficult to make out, but the thickness of their walls usually 
reveals them, as well as the phloroglucin-test, which stains 
them a bright red, while leaving the adjacent cells entirely 
untouched. These elements, which evidently constitute 
a transfusion-tissue, connect the xylem of the bundle ob- 
liquely with the palisade-tissue. The endodermis is, in places, 
occasionally interrupted by them. Loew 1 seems to have been 
the first to notice these elements. He devotes some space to 
the description of them and their position in the ridge, 
mentioning their exact position as seen in a transverse section 
of C. pnmila , with regard to the bundle and the other portions 
of the tissue (Figs. 1-6). We shall have more to say about 
this tissue in describing the longitudinal section. Parenchyma, 
consisting of rather large, empty-looking cells, constitutes the 
remainder of the cortex. 
There is a normal endodermis present surrounding the 
central cylinder (Fig. 2), followed by a rather indefinite, 
probably pericyclic layer, one or two cells thick, which is 
sometimes sclerotic opposite the phloem, and may at that 
point form a thick strand of sclerenchyma. 
The pith and primary medullary rays consist of parenchyma 
fairly similar to that of the cortex, and, together, form a star- 
shaped mass. The cells are often pitted. 
1 Loc. cit. 
