436 
joints, sometimes even more. In the upper parts of the plants, however, in partic- 
ular of the sex plants, the trichoblasts may follow immediately after each other on 
Fig. 387. 
Polysiphonia atrorubescens. 
Basal portion of trichoblast 
with axillary shoot. 200 : 1. 
the consecutive joints. In the male plants, the fertile tricho- 
blasts are usually densely crowded at the upper end of the 
shoots, each joint bearing a trichoblast. 
The angle of divergence of the trichoblasts must be de- 
termined at the upper end of the shoots, for torsions take 
place later. It is usually !/; or nearly so. In a male shoot I 
found it 1/,. On the other hand, in short branches I found 
a divergence of 4/5. The spiral always turns to the left; in 
one short shoot only I found a spiral turning to the right. 
The trichoblasts have the same structure as in the other 
species; they are much branched. The cells of the fully devel- 
oped trichoblasts contain two or more nuclei; two nuclei 
most frequently occur (fig. 386), but four were repeatedly 
met with. 
The branches arise as axillary buds to the trichoblasts, but only part of the 
trichoblasts, mostly those of the lowermost part of the shoots, are accompanied by 
shoots; these are placed at the left side of the trichoblasts. The first joint of the 
branches common to the branch and the trichoblast has three or four pericentral 
cells. The pit connecting (the second 
joint of) the trichoblast with the 
central cell in the basal joint is 
situated in the longitudinal wall 
between the outermost pericentral 
cell to the right and the cell next 
to it (fig. 388 A). The branches are 
given off from the axes under a 
rather acute angle, and they are 
often connate with the joint above 
to some extent. It may even rarely 
occur that the second joint of the 
branch is entirely connate with the 
mother shoot. The first trichoblast 
of the branch is always situated 
on the left side of the 3rd to the 
6th joint (fig. 388 B). The basal 
cells of the shed trichoblasts often 
produce secondary axillary shoots, 
Fig. 388. z 
Polysiphonia atrorubescens. A, portion of branch showing the 
pitx connecting the central cell of the basal joint with (the rest 
of) the trichoblast fallen off. B, portion of branch showing the 
basal cells (X) of the three first trichoblasts. 150 : 1. 
developing into short shoots, sometimes fructiferous but often reaching only a very 
slight degree of development. In these shoots, as in the primary ones, the first tri- 
choblast arises on the left side. As mentioned above, endogenous adventitious shoots, 
