form were often filled up by hypha-like cells, a phenomenon which, according to 
FALKENBERG, frequently occurs in the pericentral cells of P. elongata. 
The attachment organ of the frond is conical, built up of numerous densely crowd- 
ed descending filaments forming the continuation of the filaments of the cortication, and 
of rhizoids mostly given off from the latter (comp. L. Barren 1923 pp. 279, 297, fig. 47). 
Fig. 357. 
Polysiphonia elongata. A, longitudinal section through the central part of an old stem, showing the central cells and 
the pericentral ceils connected with multiple secondary pits. 100:1. B, transverse section of a similar stem, at the 
level of a transverse septum, showing the pits. 290: 1. 
The antheridia occupy the main axis of the trichoblasts except the two first 
joints, the upper of which bears a sterile branch on the right side. Sometimes the 
third cell is also sterile and then bears a sterile branch on the left side. In the first 
case it happens that the branch becomes fertile and the trichoblast thus bears two 
antheridial bodies (fig. 358 to the right), and trichoblasts bearing three antheridial 
bodies were met with too (fig. 358 above). In the branch shown in the same figure 
an antheridial cushion even occurred on the stem (comp. L. K. R. 1903, p. 465). 
In the procarp-bearing trichoblasts the first branch is seated on the 4th joint 
but not always on the right side, frequently on the left side. The ostiole of the 
cystocarp is fairly broad, not protracted and directed obliquely upwards, but more 
upwards than forwards (fig. 359, comp. Harv. pl. 292, 293). I have, however, met 
with cystocarps thicker than those figured by Harvey and me and provided with 
a short spout. 
