326 
frequency to the right and to the left. 
The ramification of the branches begins 
from the very base but the first bran- 
ches are not as a rule included in the 
spiral arrangement. Most frequently the 
first two or three branches are biseriate 
in a transverse plane. The ramification 
is often pseudodichomous (camptopodial 
Nägeli), in particular in the upper part 
of the plants, the branches reaching the 
same size as the mother axis and di- 
verging almost equally with this from 
the original direction of the mother 
axis, for which reason it is often diffi- 
cult to decide which of the rays is the 
main axis and which the branch. When 
Fig. 240. the pseudodichotomous ramification is 
Callithamnion corymbosum. À, i 
upper end of shoot. B, some- Very pronounced, the greater sections 
vies allen cols 2508 We of the frond may get a semicircular 
outline; when the main axes are more 
vigorous than the others, the outline becomes pyramidal. In 
other cases the outline is more indistinct, the greater complexes 
of shoots being dissolved in smaller corymbous bunches. Very 
rarely two branches were found on the same joint; they were 
not opposite but diverging with an obtuse 
angle from one another (fig. 241). 
The young cells contain a single nucleus; 
later on it divides and as a consequence of 
continued divisions the older cells contain a 
great number of nuclei equally distributed 
over the cell (fig. 242). They are distinctly 
Fig. 242. visible in the figures of THURET (1878, pll. 
Callithamnion corym- 33—35). 
ee pee Hyaline hairs normally occur. They have 
nuclei. 200 : 1. been mentioned and partly figured by Ktr- 
ZING, NAGELI, THURET, KYLIN and myself 
(1911). They are present in the whole season of vegetative 
development, but are wanting in winter (December, January). 
No specimens have been collected in February and March, but 
all the specimens collected in April to October were provided 
with hairs. Only in very rare cases were the specimens collect- 
ed in summer devoid of hairs; thus, some large specimens from 
Herthas Flak in 20 to 23 meters depth had only very few 
I 
Fig. 241. 
Callithamnion corymbo- 
sum. A joint bears two 
branches (III) at the upper 
end. 200: 1. 
Fig. 243. 
Callithamnion  corymbo- 
sum.A,Upperend of branch 
with terminal hairs. B, the 
hairs are pushed aside 
by the sympodial develop- 
ment of the branch. Two 
hairs are shed but their 
basal pits are still visible. 
A 240:1. B 300:1. 
