24 Veit Brecuer WITTROCK. 
above, the lateral and cone-shaped process does not appear immediately 
under the top of the cell, but a space below it, which space is in general 
about as great as half the diameter of the mother cell. On this depends 
the circumstance (mentioned page 4), so peculiarly characteristic in 
Pithophoracew, of having the branches not at the very top of the sup- 
porting cells, but a space below it. The small process formed in the 
manner mentioned above is elevated more and more, and little by little 
elongates, till it attains the form of a cylinder with a rounded top and 
with its base, as it were, contracted (pl. 3, fig. 2 6). This process has. 
in general a position so as to form an angle of about 45 degrees with 
that part of the mother cell which is situated above the process. When 
this process has attained a length which exceeds the diameter of the 
mother cell 2—6 times, a cell-wall is formed at its base, which sepa- 
rates the process, as an individual cell, from its mother cell. This cell- 
wall, which is formed exactly in the same manner as the transversal 
cell-walls in the principal filament, has, now and then, a position so as 
to be almost rectangular to the process (pl. 4, fig. 2 and 6 w), but 
generally it is placed obliquely against this axis, with an evident incli- 
nation downwards (pl. 3, fig. 7 w; pl. 4, fig. 3, 4, 5, 11, 18 w, and 
others). Thus we find here an exception from the law indicated by 
HormeisteR in Handb. d. Phys. Bot. Band I, Abth. 1. page 129, that 
the parting wall formed at the bipartition of cells is rectangular to the 
direction in which the strongest preceding increase of the cell has taken 
place.) The daughter cell formed in the manner indicated above, and 
placed at the side of its mother cell, and having as a rule a diameter 
17—1/, shorter than that of its mother cell, now increases in length. 
When it has grown about twice as long as the mother cell, it is divided, 
in the usual manner, into two daughter cells, a lower one somewhat 
shorter, and an upper one somewhat longer. It happens, more rarely 
in sterile specimens, but oftener in fertile, that the branch cell, developed 
from a cell of the principal filament, is not divided, in which case the 
branch remains of course unicellular (pl. 1, fig. 8 6); but if a formation 
of spores (in fertile specimens) in the branch cell takes place later, it 
is thus made bicellular (pl. 2, fig. 4 6). Such branch cells do not, asa 
rule, attain a length so considerable as that of those which are to form 
new cells by bipartition. If, as the case most frequently is, the branches 
1) »Die theilende Scheidewand steht senkrecht auf der Richtung des stirksten 
yorausgegangenen Wachsthums der Zelle». Horm. l. c. 
