322 
other. The branches of the main axes are spirally disposed with an angle of diver- 
gence of about !/, or between !/; and 14/,. The branches of the second and higher 
orders are arranged in a spiral as those of the first order, except the first 1—5 which 
are alternate, biseriate and arranged in a transversal plane. The ultimate short 
branches bear only biseriate pin- 
nule. A sympodial ramification 
does not occur. The branching 
designated with this term by NA- 
GELI (1861, p. 305—306) is really 
monopodial, the end of the growing 
axes being only bent by the deve- 
loping branches. For further details 
of the arrangement of the branches 
reference may be made to my 
above quoted paper (1920 p. 7). 
The pinnulæ are all acuminate 
when their growth is arrested. Only 
exceptionally a feebly developed 
obtuse pinnula may be met with 
(fig. 234). The lower cells are 3— 
5,5 (6) times as long as broad, 
usually 4—5 times as long. Hairs 
do not occur. 
The older cells contain a great 
number of nuclei, but also the 
younger cells are polynucleate and 
this stage is not unfrequently pri- 
mitive, the apical cell and the 
youngest segments containing each 
two nuclei (fig. 235). But in other 
of cases the uppermost cells are uni- 
Fig. 235. 
Callithamnion tetragonum var. fruticulosa. A and B, upper ends of nucleate ; this is particularly the 
growing plants showing the nuclei. C, upper end of branchlet with case in the pinnulæ when the 
arresting growth. D, part of stem cell with corticating filaments on 0 1 
showing the nuclei. A, B, C 350:1. D 203:1. growth has arrested, but it is also 
frequently met with in growing 
axes (fig. 238). In such cases the 4th or 5th cell from the top usually contained 
more than one nucleus. In the decurrent filaments, the apical cell may contain 
numerous nuclei (fig. 235 D). The chromatophores are numerous, in the young cells 
they are rounded or oblong discs, in the older they are longer and irregularly bent. 
The tetrasporangia are obovate, 74—81 x long, 46—61 w broad, placed on the 
inner face of the pinnæ, in their under part!, sometimes only on the undermost cell, in 
* According to Harvey, 1. c. p. 232, pl. 35 fig. 5, C. Baileyi appears to differ from our plant in 
