ARCHER, ON PALMOGL@A MACROCOCCA. 115 
see, as regards the plant in question, is, I think, proved by 
it being met with, as I have often found it (always supposing 
that I am right in my identification of the species, of which, 
indeed, I have myself no doubt) unaccompanied by filaments, 
or these so sparing as to render Kiitzing’s description of the 
plant as inappropriate as, so far as I can see, the introduction 
of these filaments into the generic character at all is erro- 
neous. In regard to his Cylindrocystis crassa, De Bary omits 
any notice of such filaments altogether; yet, as I before 
indicated, I believe these plants are identical. 
But, in order to explain the occasionally occurring pecu- 
liarity alluded to, in the mode of growth or self-division of 
the cells themselves in this plant, dwelt on by De Bary, I 
shall momentarily draw attention to that which prevails in 
the entire of its allies, and then advert to the variation some- 
times met with in this species itself. 
In the related species of Penium, Spirotenia, Cylindrocys- 
tis, and Mesotzenium (as well as those elongate, but apparently 
not at all related, forms included in Gleothece (Nag.), 
Stichococcus (Nig.), &c. &c., the direction of self-division 
occurs always in a line at the middle, at right angles with the 
original longitudinal axis of the mother-cell. Now, in Cylin- 
drocystis Brébissonii, along with the elongation of a cell, 
preparatory to self-division, a longitudinal extension and a 
transverse subdivision of the central corpuscles belonging to 
each of its halves take place, thus causing the now. two 
corpuscles of each half to lie in the direction of, and on a 
line with, the longitudinal axis of the original mother-cell. 
Presently ensues a segmentation and division into two of the 
cell itself at the middle, in the transverse direction, and, as 
stated, in a line at right angles to the longitudinal axis, the 
original nucleus vanishing, and a new one for each half, that 
is, each daughter-cell, making its appearance, according to 
De Bary. In C. crassa (De Bary) =Trichodictyon rupestre 
(Kiitz.), previous to division of the cell itself, there is no 
subdivision of the central corpuscle of each half, but on the 
formation of a septum it seems to ensue. Its subdivision 
may_take place then, either after the manner of C. Brébissonii, 
in a transverse direction, causing the two new corpuscles to 
lie in the direction of the longitudinal axis of the mother- 
cell, that is, perpendicular to the new septum, o7 the sub- 
division of the central corpuscle of each half of the mother- 
cell may apparently take place in a direction on a line with 
the longitudinal axis of the mother-cell, causing, in this case, 
the two new corpuscles to lie in a direction perpendicular to 
the original axis of the mother-cell, that is, parallel to the 
VOL. IV.— NEW SER. I 
