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PROCEEDINGS OE SOCIETIES. 
about, as it were on the surface of the endochrome. They are, doubt¬ 
less, identical in nature with the similar active granules in Closterium, 
Penium, &c. I have not been able to detect any appearance indicative 
of the occurrence of a circulation, except it may possibly be inferred 
from the up-and-down movement of these errant granules. But then, 
when the cell is broken by force these active granules appear to be more 
numerous, apparently arising from similar granules becoming disengaged 
by the pressure from the mass of endochrome, and themselves setting-up 
a movement in the surrounding water, of the same quivering, agitated 
character (Pig. 4). Those who have seen the “ molecular” movement of the 
granules of the fovilla of pollen will, to my mind, have abetter idea than 
I could convey of the appearance presented by these moving granules 
when pressed-out, only they are not so numerous. Perhaps there may 
be a current within the cell, and that the fluid contents between the 
mass of endochrome and the margin of the cell may be of too great tenuity 
to enable it to be detected; at all events, I have not seen any of these 
free granules carried directly and steadily onwards, similarly to what 
occurs in other vegetable cells. I apprehend, however, that the curious 
“molecular” movement displayed by the pressed-out granules is only 
just a continuation of the same movement to be seen within the joint, 
and that the additional granules moving about when forcibly expelled 
would have also moved in the same manner inside, could they have been 
disassociated from the mass of endochrome in situ . "When by violence 
one of these joints is broken, the separation takes place by a suture at 
the centre over the pale space, and by a smooth line of division. 
Of such joints as I have thus endeavoured to communicate an idea 
are the filaments composed of which the plant is constituted, and which 
for some time, attached to aquatic plants, maintain their connexion as a 
filament (Pig. 3). There does not appear to be any dilated or scutate base 
by which the first joint is attached to the foreign objects, but on which 
the filaments seem to stand directly, and with which the truncate apex of 
the first joint appears merely to be in apposition. The joints frequently 
separate, however, and can be met with in the water singly. Indeed, 
my first acquaintance with this organism was made with a single detached 
cell. They increase in length, too, sometimes after separation. 
The division of the joints into two segments by a suture, although 
there is no transverse stria or other perceptible indication in the unbroken 
cell-wall of its existence, coupled with the interruption of the endo¬ 
chrome into two distinct portions, as well as with the active granules, 
seem at once to decide that this organism belongs to the Desmidiaceae. 
The particular mode of increase by cell-division which prevails 
amongst the other Desmids (by the formation of a septum and by the 
interposition of new growth between the old, unaltered segments 
pushing them asunder, and afterwards becoming divided at the middle, 
each half of the newly grown portion ultimately attaining the size and 
form of the old segments, and usually becoming cut off, and separation, 
taking place), I need hardly repeat, is abundantly evident and unmis- 
takeable amongst the more elaborately formed bipartite genera; whilst 
