212 МВ. W. ARCHER ON THE MINUTE STRUCTURE AND 
important interest of the specimen, then, attaches rather to its being the first in which 
the specialities alluded to have been noticed. 
The whole plant is of a rigid and tough character; nor, when it is viewed under the 
microscope, is this surprising, when the cell-wall is seen to be so very thick, composed 
as it is of several lamina. Now the peculiar and interesting internal character alluded 
to is, that in the boundary walls of the cells or “joints” there occur always two op- 
posite terminal, and in some of them, in addition, two lateral, pairs of more or less 
wide (seemingly circular) pits—a character, indeed, found in other Rhodophycez, long ago 
pointed out by Nageli*; but what would appear to be novel (so far as I know, indeed, it 
is unprecedented in other departments of plants $) is, that each of these pits is covered 
by a comparatively large lid or stopper, not organically united or persistently adherent; 
at least very small accidental force seems to suffice to dislocate and remove them. 
In Mr. Moseley’s example, in every joint of the plant, whether of the main stems or 
rachises or of the ultimate ramifications (except the apical joints), there occurs a “ pit,” 
with its “ stopper," at each end of each joint—that is, at least two such in each cell (see 
the figures passim); in the apical joints there occurs but one (at the base). In many 
cells of the rachises and of certain lateral cells (presently to be noticed) there occur besides 
yet other pairs of smaller pits and stoppers, as will be hereafter explained. Why these pits 
* ‹ Die neuern Algensysteme.’ 
+ Something optically resembling the “ stoppers” above referred to presents itself during the conjugated state of 
Mesocarpus nummuloides. It is well known that in Mesocarpus the spore is formed within the transverse canal (formed 
in the characteristic manner between the two conjugating cells) by the passage thereinto of their chlorophyll- 
plates enclosing the granular and oily contents, which become massed in the middle, whereupon ensues the division 
of the now H-shaped cell into three by formation of two septa, one to each side of the transverse canal, the middle 
cell becoming the spore, the two limbs (the parent cells) cut off seemingly as effete, though still containing colourless 
slightly granular plasma. As maturity advances, and when the spore presents its three consecutive walls, the median 
brownish and coarsely scrobiculate, it is seen to be ultimately freely suspended in the surrounding medium, but still 
posed between the somewhat geniculately bent pair of parent cells. Now, in addition to the original septum cutting 
off the primary parent cells, the outer apertures of the disjunct transverse canal, now separated at both sides from 
the free spore, is seen to be covered by a plano-convex “ lid,’ much thinned off at the periphery, of a semipellucid, 
somewhat “ pearly,” aspect, and sufficiently strongly calling to mind the appearance of the “ stoppers " in Ballia above 
referred to. This lid in Mesocarpus may be seemingly composed of a condensed kind of mucus. What its purport, I 
could not hazard a conjecture; but it certainly appears puzzling that so much pains, as it were, should be expended 
on hermetically * sealing up” these apertures in a structure whose function would appear to be over, containing, 
indeed, some as yet living (?) plasma, though robbed of its chlorophyll, but nevertheless seemingly destined to be but 
east off as of no further moment. 
The **lids" here adverted to are often, indeed, sufficiently obvious; yet I do not know that they have been 
noticed in algal works. Their possessing a certain amount of resemblance to the stoppers in Ballia renders an allusion 
to them here possibly not altogether out of place, though in the case of Ballia the stoppers are within the cell-cavity, 
: but external to the “ primordial utricle," whilst in Mesoezrpus the corresponding structures are (at least ultimately) 
external to the eell—that is, washed by the surrounding water: still their deposition must presumably have been 
carried on, at least begun, whilst the spore-cell remained organically united or in intimate apposition with the parent 
_ Whether, as suggested by Prof. Dyer, the “hemispherical depositions of cellulose” sometimes met with on the 
inner side of the pollen-cell wall, е. у. in Cucurbita реро (Sachs's * Text Book, р. 32, woodcut v), are to be considered 
analogous to the structure (“stoppers”) here adverted to is probably questionable, but is doubtless deserving of 
further investigation. 
