548 REPORT—1883. 
five protoplasmic threads, a feature which gives sections of this plant a most 
characteristic appearance. 
The genus Ptilota, so much admired for the beauty of its forms, is no less 
remarkable for the striking examples it offers of protoplasmic continuity. This 
is especially true of P. elegans. Fundamentally monosiphonous, so to speak, the 
older parts of this species become densely corticated, though the ultimate divisions 
of the frond are simple filaments composed of oblong or quadrate cells. The proto- 
plasmic bodies of these cells are in uninterrupted continuity, and the basal cell of 
each branchlet is connected with a cell of the branch from which it springs, From 
these ultimate branchlets the continuity may be traced backwards without a break 
to the main axis of the frond, along which it may be followed by the help of 
sections. The cells of the cortex are likewise connected inter se, and with those of 
the axis they enclose, so that here, too, the contents of the different cells are in 
direct communication throughout the whole plant. 
Other genera, in which corresponding appearances are presented, are Worms- 
kioldia, Delesseria, Plocamium, Cystoclonium (Hypnea), Gigartina, and Chondrus. 
Of these the author has examined numerous species, with the result that in 
no single instance are the connecting threads of protoplasm running from cell to 
cell absent. To describe the phenomena in detail would be to repeat what has: 
already been said. Chondrus and Gigartina may be referred to as differing histo- 
logically from the other genera, and, indeed, from one another; but they are at 
one with them in the matter of protoplasmic continuity. 
Of all the genera examined one of the most interesting, from the point of view 
of this paper is Zaurencia. In L. pinnatifida the size, shape, and arrangement of 
the cells vary much in different parts of the thallus, but in every part the proto- 
plasmic bodies present a most remarkable appearance. From the surface of each, 
at various points, are given off radiating processes, which run along channels or 
pits in the thickened wall, and finally meet and blend with similar processes from the: 
adjoining cells. These processes are invariably so stout and distinct as to give to 
the cell-contents the appearance of a Rhizopod with short thick pseudopodia. 
Of fresh-water Floride, the author has examined Batrachospermum and 
Chantransia, both of which exhibit evidences of continuity. 
Coming to the question of origin the author is of opinion that the connecting 
rotoplasmic threads under consideration, originate, as a rule, in the manner de- 
scribed by Professor E. P. Wright for Polysiphonia urceolata. As a matter of fact, 
the process of cell-division in the Floridez here dealt with, and probably in all, 
never becomes completed, so that the parts of a divided cell remain connected 
together by one or more threads of protoplasmic material. Nor are these threads 
merely temporary structures. On the contrary, save where accidentally broken, 
they are permanent, being met with in the older parts of the plant as constantly 
as in the younger. Again, these threads are not dead, but possess the vitality and 
power of growth of ordinary protoplasm. This is proved by the facts that, as a 
rule, they become stouter with age, and give rise to differentiated structures. For, 
simultaneously with the thickening of the threads, a peculiar structure is developed 
by each at about its middle point. This usually presents itself in the shape of a 
ring or collar, as may be readily seen in Callithamnion, Polysiphonia, Laurencia, and 
other genera. In some cases an extremely thin diaphragm is developed within this 
collar. The nature of this it is difficult to determine, but that it is not a cellulose 
partition seems to be indicated inmany ways. For instance, it colours with iodine 
and aniline dyes in the same way as the protoplasm, while the cellulose walls are 
altogether unaffected. Moreover, when by desiccation of the specimen the proto- 
plasm shrinks from the cell wall, it does not shrink from the ring and diaphragm, 
continuity being as perfect in dried material as in fresh. Lastly, when the con- 
tinuity is broken mechanically, the fracture may occur at any point of the thread, 
and not necessarily at the collar. 
