ARCHER, ON STEPHANOSPHERA PLUVIALIS. 193 
Mesotenium mirificum, which I brought before the society 
during last session.* Here the contents of a single Meso- 
tenium cell escape therefrom without conjugation through a 
lateral or terminal or variously disposed opening, effected by 
the raising up of a lid- or valve-like portion of the membrane 
of the parent-cell. ‘During this act the emerging contents 
are often much constricted by reason of the narrowness of the 
aperture by which they make an exit, and after emergence 
the mass becomes rounded. Now, Mesotznium is a plant 
which does not generate zoospores, and whose developmental 
stages are regarded as quiescent, yet here the protoplasmic 
mass, wonderful as it may (at first sight) appear, actually 
comes forth into freedom, through an opening very consider- 
ably smaller than even the narrowest diameter of the former. 
This paradox is solved by witnessing the phenomenon :— 
a lobe-like extension—I might write a pseudopodal process— 
is protruded through the opening ; a portion of the contents 
is slowly drawn after, thus relieving the mass behind, which 
contracts upon itself; and the gradual extension and expan- 
sion of the portion outside the old membrane by degrees 
draws with it the whole ; and its purpose, whatever it portend, 
is gained—that is to say, the whole protoplasmic mass and con- 
tents have acquired their freedom, and the old parent-mem- 
brane is discarded and deserted. What immediately becomes of 
the “ chlorophyll-plate” in this process I cannot say, but the 
whole contents become more granular, in which I suppose 
the plate likewise takes a part; or possibly it becomes con- 
solidated in the centre, causing the dark central spot in the 
spore-like body formed by the emerged contents—it, at all 
events, affords no obstacle to a process which at first sight, 
and until it is properly considered, appears almost like a feat 
of legerdemain. 
Not to multiply examples, let us refer, lastly, to the modus 
operandi of the process of conjugation in the genus Spirogyra. 
Two filaments in juxtaposition about to conjugate put forth 
from opposite cells, asis well known, short tubular processes, 
lined by a similar extension of the “primordial utricle” 
bounding their contents. This, indeed, so far seems to be only 
a process of growth, comparable to that which takes place in 
a joint of Cladophora when about to give forth a branch, or 
to that of the apex of the tubular filament of Vaucheria, &c. 
&e. But in the conjugating joints of Spirogyra an actual 
contact and resorption of the intervening septa having taken 
place, so as to produce an uninterrupted connecting canal, 
* «Proceedings of the Natural History Society of Dublin,’ vol. iv, part 
i, pl. i, figs. 21, 22; also ‘Quart. Journ. of Mic. Science,’ vol. iv, p. 109. 
