206 MAJOR-GEN. NELSON AND PROF. DUNCAN ОМ THE 
Deeper still in the frond the linear series of cells, which are placed radially, are seen. 
to branch; or, rather, two or three series unite deeply in one, and the size of the inner 
cells increases. АП are very distinctly separate by their sides after the action of acid. 
Amongst these deeply seated cells there are some which are long and fusiform ; they run 
longitudinally through the joint, and deeply. "They are observable in the middle joints, 
and not in the younger and terminal ones of the young frond. Each is crammed with 
two or more linear series of slightly flattened spheroids of colourless matter, very amyloid 
in appearance. And whilst in some a mass of dark port-wine-coloured cytioplasm may 
exist at one end, and a series of the amyloid bodies at the other, the majority of these 
cells, which sometimes bifurcate, are colourless; and in many no cell-wall can be distin- 
guished, on account of the close packing of the contents. (Plate X XVII. fig. 9.) 
These long cells, with their remarkable contents, are in relation with the filiform 
cellular processes of the articulations, and are often distinctly continuous with them, 
especially with the deeply seated ones, which run in a longitudinal direction throughout. 
Each articulation consists primarily of a mass of long cells placed between the joints, 
and it has a deep and a superficial part. 
The superficial part of the articulation consists of a thin layer of epithelium-looking 
cells, well seen by polarized light, and which is continuous with the common superficial 
layer of the frond; then follow long cells crowded closely together, and having a faint 
green tinge. Each cell has a thick wall, which is more transparent than the elongate 
protoplasmic contents; and usually the cell is long enough to extend from one joint to 
the other. It then is fixed on to a broader and shorter cell, whose direction is oblique 
and more or less radial; and it contains more or less colouring-matter, green or dark red. 
This obliquity of the outer layer of the articular cells close to the joint produces decom- 
position of the polarizing ray, and the phenomena of alternating light and darkness and 
of complementary colours. 
The deeper cells of the articulation are elongate, like the others; they are very long, 
numerous and crowded, and have thick cell-walls and a linear mass of cytioplasm. 
They pass straight on in either joint, and merge into long cells without colouring-matter, 
or else into a series of the fusiform cells noticed above. ! 
It appears, from examining very young specimens, that the outer part of the articula- 
tion is developed from the outer layers of the joints by elongation of their cells, and that 
the deeper layers are produced from the elongate and longitudiual series of the frond. 
As growth proceeds, the fine tissue on the articulation is lost, the long cells increase 
in breadth and length and in the thickness of their walls, their contents becoming 
semi-solid, 
Occasional dissepiments occur in the long cells of the articulation, and also short pro- 
cesses of the cell-wall; but often they are not visible. Polarized light, however, is à 
great assistant in the investigation. 
A small amount of carbonate of lime is found amongst the superficial layer of cells; 
but it does not appear to exist in and amongst the deep and long cells of the articulation- 
Іһ older fronds, and in some Corallines from Port Natal, the superficial epidermic 
layer is very distinct; and beneath it the cells of the first layer of the mass of the frond 
