HISTOLOGY OF CERTAIN SPECIES ОҒ CORALLINACEJE. 203 
growers in comparison with the species of temperate seas; and they contain less carbo- 
nate of lime, joint for joint, than the well-known Corallines of our seas, although the 
whole plant may contain much more. Their cells are larger, and the whole plants present 
in their minute anatomy a great resemblance to some other little-known Bermudan 
Algee, but which, whilst they resemble filamentous Rhodosperms, include carbonate 
of lime within their cellular tissue. The function of the filamentous processes and of 
the external delicate membrane can be readily interpreted. They are the only means by 
which absorption of the sea-water, and therefore of nutriment and carbonate of lime can 
take place. When once the intercellular spaces and the cell-walls have become infiltrated 
with granular carbonate of line, no further nutrition can proceed. At this time the 
deposit is free to collect within the cells; for the cytioplasm contains it. When large 
cells are cut into, they emit a rice-water-looking liquid, which deposits granular car- 
bonate of lime. 
The fronds increase, as it were, exogenously, by division of the external cells of the 
layer which gives origin to the filamentous processes. The superficial epidermal layer 
also develops a succession of external coatings to the frond; and therefore several of the 
above-mentioned layers are derived from it. The arrest of growth and the deposi- 
tion of carbonate of lime have evidently some common relation. Hence in all probability 
the introduction of the mineral in the soluble form of the bicarbonate into the cytioplasm, 
cell-wall, and intercellular space progresses during the early life of the frond and whilst 
growth is proceeding. But as starch, cellulose, and carbonaceous granules accumulate, as 
growth becomes less vigorous a part of the carbonic acid of the bicarbonate is decom- 
posed, part is retained, and part is lost, and the insoluble carbonate of lime is precipi- 
tated in the granular form. 
The merging of one cell into another (the “copulation” of Rosanoff) has not been 
observed in the Bermuda Corallines ; nor has any thing like a regular porosity of the cell- 
walls. But the presence of round spots where the cell-membrane is thin and more per- 
vious to light is occasionally to be noticed in decalcified specimens. 
In the cell-wall of the long internal cells there are markings which indicate a differ- 
ence in the thickness of the wall; and on the surface of the frond the delicate external 
epidermal layer may be distinguished by curious puckerings and markings in its delicate 
tissue. 
IV. The Histology of the Epiderm of the Frond of Corallina officinalis from temperate 
seas; notice of the Structure of the Celis of the Mass of the Frond. 
The common British Corallina officinalis should be studied in the early spring time ; 
for then its origin, from a greater or less expansion, may be examined, and there is 
then not much carbonate of lime in the frond. The expansion and short stumpy 
fronds are of а beautiful.claret or port-wine-and-water colour, the articulations and the 
tops of the joints being greenish or colourless. Care should be taken to remove the 
Stone to which the plant is attached without any washing movement ; or the delicate 
external layer will be destroyed. The microscopic specimens, sections, &e. had better 
be mounted in glycerine; and if any acid be used, it should be weak hydrochloric 
