10 Verr Brecuer’$Wirrrock. 
The terminal vegetative cells ‘are also of two kinds: the common 
top cells, and the helicoid cells. The common terminal cells resemble in their 
form the inclosed cells, with the exception that they have the top conical 
and rounded. As to their inward construction they agree with the 
inclosed cells. As long as the individual is increasing in growth they 
are rather rich in chlorophyll, but when the imcrease has ceased, they 
contain comparatively little chlorophyll. The top cells are the longest 
cells of the plant. In sterile specimens, where the increase has ceased, 
the top cell of the principal filament often has a length which is 
50—100 times as great as the thickness (pl. 2, fig. 8). 
Helicoid cells I name those cells, of which the top is transformed 
to an affixing organ more or less like a tendril, a helicoid (rom gé = 
tendril, and «ido = form). These cells are common only in one species, 
P. Cleveana nob., but also in the other species of Pithophoracee, with 
the exception of P. sumatrana (v. Mart.) nob. and P. equalis nob., I have 
found them now and then. The lower part of the helicoid cells is 
generally of a cylindrical form, but their upper part, the helicoid, is of 
a very varying shape. In its least developed form the helicoid cell is 
unbranched or almost so, and differs then as to shape from common 
terminal cells only by its upper part, the helicoid, bemg more slenderly 
conical, and not straight, but curved, feebly undulating (pl. 5, fig. 1 h’ 
and 2 h). In normally developed helicoid cells the top of the cell is 
ramified in two or more small branchlets. The branchlets of the helicoid 
are sometimes almost straight, with only a few small undulating curves 
(pl. 5, fig. 4); sometimes they are bent like a bow (pl. 5, fig. 5, 7), but 
most frequently they are quite claw-shaped (pl. 5, fig. 6, 11, 12; pl. 1, 
fig. 18 h): The contents in the lower part of the helicoid cell are of the 
usual nature; i the upper part, or the helicoid itself, chlorophyll-co- 
loured protoplasm exists in a quantity so great as to fill this part of 
the cell almost completely (pl. 5, fig. 4, 6, 7, 10 h). Even if the quan- 
tity of chlorophyll-coloured protoplasm be not always so great, it is 
however, as a rule, greater in the helicoid itself than in the rest of 
the cell (pl. 5, fig. 1 h, 5, 11, 12 A). A phenomenon which oceurs 
regularly, at least in P. Cleveana nob., viz. that small foreign particles 
(grains of humus and other things) adhere to the surface of the helicoid 
(but not to that of the other part of the helicoid cell), mdicates that 
the cell-membrane of the helicoid is in some degree of a nature differing 
from that of the other part of the cell. However, I have neither by 
optical nor by chemical means been able to gain a more particular 
