TRANSACTIONS OF THE SECTION. 547 
Sabellarvia alveolata, Lam. (Hermella, Quart.) Frequent within the mouth of old 
shells. 
S. crassissima, Lam.—Occasional. 
Owenia filiformis, Della Chijsa (Ammochares Ottonis, Grub.). Sparsely distri- 
buted. Tube about the thickness of a crow-quill, covered with short angular shell 
fragments, closely imbricating each other. Allied to Clymene. 
Terebella arenaria, L.—Abundant on the Birkdale shore near low water. 
T. conchilega, Poll. 
T. nebulosa, Mont.—Attached to shells and roots of ferns cast up after 
storms. 
Serpula contortuplicata, S. triquetra, and several varieties of Spirorbis and 
Sabella, are also found among the roots of Laminaria, Xc., drifted from without. 
10. On Protoplasmic Continuity in the Floriden. 
By Tuomas Hick, B.A., B.Sc. 
In the hope of throwing some light upon the interesting and important 
question of protoplasmic continuity in vegetable tissues, the author has made an 
extensive series of observations on a large number of species, belonging to several 
genera of Florideze, with special reference to this question. He finds that in every 
species hitherto examined, the histological structure is such that, except where 
accidentally interrupted, there is an unbroken continuity of the protoplasmic sub- 
stances of the plant from the base of the frond to the tips of the ultimate branchlets. 
In the normal condition the protoplasmic body of every cell is connected, by means 
of one or more protoplasmic threads, with the protoplasmic bodies of contiguous 
cells, however numerous these may be. These threads pass through apertures in 
the cell walls, by which the contents of the respective cells are separated. 
In the simpler filamentous forms, such as Petrocelis cruenta, Griffithsia setacea, 
Callithamnion Rothii, and the like, the mode in which continuity is effected is 
comparatively simple. In these cases the contents of each cell are connected 
longitudinally with the contents of the next higher or lower cell by a single, fine, 
protoplasmic thread, lateral connections only appearing where the basal cell of a 
branch is connected with a cell of the main axis, 
The stouter forms of Callithamnion, e.g. C. tetragonum and C. arbuscula, are 
provided with a cortex composed of filaments which arise from the bases of the 
lateral branches, and, growing downwards, become adherent to the axial cells. In 
this cortex, as well as in the axis itself, protoplasmic continuity is a marked 
feature, an important point being that in the larger and older cells the protoplasmic 
connections are no longer fine threads, but comparatively stout cords. 
-In genera where the thallus obtains a higher degree of complexity, the 
arrangements for the maintenance of continuity are more elaborate. Professor E, 
P. Wright has shown that in Polysiphonia urceolata, P. fibrata, and P. atro- 
rubescens, the protoplasmic bodies of the central siphon are longitudinally con- 
nected, as are also those of the cortical siphons; while the contents of each central 
cell are similarly connected by transverse radial threads with those of the sur- 
rounding cortical cells. The author’s observations go to prove that substantially 
the same phenomena are met with through the whole genus, and are especially 
striking and easy to make out in P. fastigiata. 
The genus Ceramium has a structure differing from that..of Polyswphonia in’ 
many respects, but agreeing with it in presenting a thallus consisting of a central 
axial row of cells, usually clothed toa greater or less extent by a cortex. By 
careful manipulation and the aid of sections, it is not difficult to demonstrate proto- 
plasmic connections between the cells, similar to those already mentioned. Such 
connections render the protoplasm of the axial cells continuous from one end to the. 
other, and bring these cells into direct communication with the cells of the cortex. 
In this genus, however, the connection between contiguous cells is made by two or 
more threads, and not by a single one, as in Polystphonia, Callithamnion, &c. In 
Ceramium rubrum, for instance, the cortical cells are often connected by four or 
NN 2 
