464 
c) Secondary axillary shoots arise from the basal cells of shed trichoblasts. 
They occur normally in P. violacea, giving rise to the shorter branches characteristic 
to this species, appearing between the longer primary branches, further in P. elon- 
gata, particularly in older, wintering plants, and in P. Brodiæi, more rarely in P. nigres- 
cens (K. R. 1884, p. 19, rés. p. 3) while they have not been met with in P. urceolata 
and in P. orthocarpa. Thus they occur also in species having no primary axillary 
shoots. In some cases they appear before the trichoblasts have been shed (figs. 
364, 394). 
d) Endogenous branches produced from the central cell of older joints occur 
in particular in the species of Polysiphonia with creeping shoots and in Brongniar- 
lella. The creeping shoots always arise endogenously and produce new endogenous 
shoots; they issue normally near the base of the principal stems in P. urceolata, P. 
orthocarpa, P. atrorubescens and P. nigrescens. In the latter species an endogenous 
shoot often appears in the axil of the longer branches, near the base of the 
branch (fig. 393). 
e) Adventitious branches arising from peripheric cortical cells occur in Rho- 
domela and Odonthalia; they have not been met with in Polysiphonia. 
4. The rhizoids are unicellular. In Polysiphonia and Brongniartella they are 
produced from the pericentral cells or in the corticated species also from the cort- 
ical cells. In the sporelings, however, the first rhizoid originates from the lowermost 
cell of the plant and the next following from the first joints which do not produce 
pericentral cells (figs. 384, 396). The rhizoids are separated from the pericentral 
cells by a wall (comp. Derick 1899 p. 251). Dr. Lizy BATTEN did not observe a wall 
at the base of a rhizoid in any species of Polysiphonia that she had observed (1923 
p. 276). Such a wall is, however, really present in all of the Danish species. In 
P. urceolala only I found rhizoids in open connection with the pericentral cell. A 
shortening of the rhizoids was stated in P. urceolata. Rhizoids are wanting in Lau- 
rencia pinnatifida, Rhodomela subfusca and Odonthalia dentata, the organ of attach- 
ment of which is a continuous pseudoparenchymatous disc. 
5. Torsion of the stems in Polysiphonia and Rhodomela frequently occurs. In 
P. atrorubescens it is a constant feature, but the direction of the torsion varies. The 
twisting may cause that the branches become uniseriate for a longer stretch (P. vio- 
lacea, P. Brodiei, Rhodomela). 
6. In most of the species the central cell contains one nucleus which remains 
undivided, while the pericentral cells are always polynucleate. In Polysiphonia ni- 
grescens and Rhodomela subfusca, however, it becomes plurinucleate by division of 
the primary nucleus. 
7. By the germination of the spores (of Polysiphonia and Brongniartella) the 
cell is first divided by a transversal wall whereby a cell is cut off that becomes 
the first rhizoid cell. In Brongniartella the rhizoid was perceivable before the ap- 
pearance of the wall. The sporeling is then divided by parallel walls into segments, 
the first one or two of which (in Polysiphonia) do not produce pericentral cells, 
