200 MAJOR-GEN. NELSON AND PROF. DUNCAN ОМ THE 
III. On the Bermuda Corallinacee ; their simple and compound filamentous epiderm ; 
the structure of the external cellular tissue of the frond, its relation to the deposit of 
carbonate of lime, and the nature of the internal tissue. 
Тһе high temperature of the sea at Bermuda, the absence of a cold season, and the 
abundance of earbonate of lime in and about its reefs, favour the growth of the Coral- 
lines and Nullipores. Under these physical conditions these plants assume an appear- 
ance of great beauty ; for in the still pools amongst the reefs they may be seen in 
luxuriant profusion, each frond being enveloped in a delicate halo of filiform vegetation. 
Instead of the white or purplish smooth exterior which is so familiar to the investigator 
of northern forms and of dead specimens, that of the living Bermuda Corallines is hirsute, 
the hard calcareous analogue of the less-favoured species of Europe being beset with 
vigorous cell-growth. (Plate XXVI. figs. 2, 11, 14, 15; Plate XXVII. figs. 11, 13.) 
In the warm sea of the Bermudas white Corallines are rare, and the prevailing colour 
is green, as in Corallina tuna, or full bright grass-green, as іп Corallina tridens; some- 
times the tint is bluish-green; and some Corallines are brownish green or even 
plum-coloured. 
Their filamentous vegetation, or cell-growth, varies in amount and in its details accord- 
ing to the species ; but in every instance it is continuous with the outer cells of the mass 
of the frond. The filaments are wonderfully varied in form * and structure: sometimes 
they are merely tubular and unicellular; sometimes they are very distinctly articulate ; 
and in some species they branch. Their length varies also; for whilst in some vigorous 
forms they exceed in length the diameter of the joint of the frond to which they are 
attached, in others they are not quite as long, and in certain species they are not more 
than y5 or зо of the length of the diameter of the plant. Many contain extremely 
minute spherules of chlorophyll or, rather, of colouring matter, whose minute bodies 
have such a significant appearance that they suggest some other physiological bearing 
than that of simple colouring matter., (Plate XXVI. figs, 3, 12, 16.) 
These filaments, radiating on all sides and crowded together, resembling a confervoid 
growth on the frond, do not appear to be contractile ; for they are passive under the | 
movements of the numerous minute animals which move up and down and in and out 
amongst them. They possibly form the food of many minute animals, and are thus 
liable to be removed from their parent frond, a process which washing and drying | 
will imitate. Nevertheless, if the algz are carefully collected and placed on paper, traces 
of the filaments will last for a long time. 
Very long filaments which are single, and һауе a direction rather oblique to the frond, 
are seen in Corallina vermicula. Filaments which are crowded and short, and which 
bifurcate, exist in Corallina tridens; and still shorter ones are observed with bifurcate 
 ànd club-shaped ends in Corallina tuna. 
| ‘Under а magnifying power of 100 diameters the outside of the dried frond of Coral- 
y In order to see them to perfection the plant must never leave the water, and should be put into a glass vessel 
under the surface, and then removed in its temporary aquarium. 
