AIG 
adventitious shools appear normally in the shoots of wintering plants. When 
the growth ceases at the end of summer, a number of shoots and tips of 
shoots are thrown off, and next spring numerous new shoots are produced, 
partly from the surfaces of the wounds, partly from the basal cells. Frequently 
a shoot is produced from each joint. When the new shoots are principally given 
off from the upper part of the wintering 
ones the form appears which J. AGARDH 
has named f. microdendron (1. e.). This 
form I have only found once (Klorgrund 
South of Hjelm in May). 
In the usual form with short joints 
the branches are to a considerable extent 
connate with the following joint (fig. 356). 
In this form the branches are as a rule 
thin at the base and become thicker 
upwards. In f. baltica this is not so or 
c only in a slight degree. 
The cortication begins early, espec- 
ially in the typical form. The primary 
cortical cells are here often of the same 
length as the pericentral cells, being cut 
off by a longitudinal wall (fig. 356). In 
the forms with longer joints, f. Schue- 
Foly RE So, “Hi belerii and f. baltica, the primary cortical 
Polysiphonia elongata. A, portion of shoot showing the + 
formation of the first cortical cells. B, nuclei and chrom- Cells are shorter and cut off by an in- 
atophores of a pericentral cell. 270: LK C, portion of a clined wall (fig. 361). The pericentral cells 
branch showing the upper end of a pericentral cell with 3 x 
MOI om coter co Cha contain numerous nuclei and the primary 
cortical cells are also plurinucleated (fig. 
356), while the central cell contains one large nucleus, at least for a long time. 
In the typical form, the pericentral cells of the thick main shoots are connected 
with several secondary pits traversing the transversal walls. In a transverse section 
one pit is found in the middlemost part of the wall and a number of up to ten 
in the periphery. The central pit is probably the first, arisen at a very early moment, 
while the others have only been formed in the following year. The cortical cells 
may also be connected by several pits in the same wall, in particular in the trans- 
versal walls. The secondary pits of the pericentral cells are much smaller than 
those of the central axis, but bigger than the pits between the pericentral cells in 
the other species of Polysiphonia and bigger than the primary pits connecting the 
central cells with the pericentral cells in Polysiphonia elongata (fig. 357).! Such multiple 
pits were not met with in f. baltica. On the other hand, the central cells of this 
" Dr. Lıry Barren figures three pits connecting two pericentral cells which are erroneously said 
to be central cells (1923 pl. 22 fig. 1): 
