198 MAJOR-GEN. NELSON AND PROF. DUNCAN ON THE 
unfrequently full of greenish granules like ehlorophyll. Тһе lime is not in the interior 
of the cells, but appears to be on the outside of the cell-walls, whieh are rendered opaque 
and thick in consequence." He examined this section with a power of 200 diameters, 
` and delineated the results * Тһе drawing shows a very irregular patchwork of white 
spaces amidst a dark matrix; and the spaces represent the irregular cells without lime 
surrounded by the calcareous intercellular mass. Some long fibres are shown to be part 
of the articulation ; and they are destitute of the mineral. Не illustrated the general 
anatomy of the plant further by making a transverse section of a joint (i e. a part 
between two articulations), and by dissolving it partly in dilute hydrochlorie acid. Тһе 
drawings t given by him exhibit the outer part of the section decalcified, and the inner 
as still retaining some carbonate of lime—so that externally there is a broad series of 
more or less hexagonal cells in radiating rows, whilst internally the cut extremities 
of the smaller cells are seen to be surrounded by opaque mineral matter. There isa 
remarkable addition to this delineation, which is not referred to in the context, in the form 
of а space included between two lines, which represents a homogeneous tissue on the 
surface of the lithophyte. 
In noticing Соға па incrassata, he explained the very flexible nature of the arti- 
culations—and that by making a vertical section of one the elongated cells of it could be 
distinguished without any lime upon them, and having often a green colour. Тһе 
delineation given of these sections shows long internal and hexagonal external cells, with 
a perfectly plain margin to the free surface of the plant. 
Finally, in noticing the absence of any such articulation-cells in the Nullipores, he 
accounted for it by their slow growth in comparison with the more rapid increase of the 
Corallines, whose calcareous covering was therefore all the less. 
It will be found on comparing Quekett’s histological work with the essay by M. L. 
. Decaisne $, that he was so far in advance of that author that it is hardly necessary to 
allude to it here. But there are some points of interest in M. Decaisne's paper, and some 
others which, if not explained, might appear to have forestalled the present com- 
munication. L 
The illustrations given by M. Decaisne are in plate 17 of the 2nd series of the Annales 
des Sciences Naturelles, 1842, vol. xvii. (the plate is marked “tom. 16”); and nearly all 
have been much improved upon by Quekett. 
But the illustration of Cymopolia barbata is remarkable. The figure (12), of the 
natural size of the plant, resembles the appearance of the structures of many Corallines 
when magnified. Fig. 124, however, explains that the endings of the frond аге dicho- 
tomous branchlets, which are covered with carbonate of lime. They thus differ from 
what will be explained further on. M. Decaisne noticed (see fig. 14 а) that a mucilage 
covered the Corallina opuntia (Halymenia opuntia), and that it formed a sort of cuticle 
which covered the surface of the articulations; but his diagram of the network of cells 
formed by the contact of those of the superficies is not in advance of that of Quekett. 
_ * John Quekett, Lectures on Histology, 1854, vol. ii. р. 169 её seq., fig. 85, p..171. 
T Quekett, op. cit. vol. ii. p. 171, fig. 85, fig. d, and fig. 86. 
+ L. Decaisne, Aun. des Sci. Nat. 2nd ser. vol. xvii. plate 17. Classification of Algw. 
