273 
nema Thuretii. I have only examined a few fully developed cystocarps on slides 
made by microtome, and they showed that the formation of carpospores is not 
always limited to the periphery of the conceptacle, but may also take place 
from the inner part of the great disc-shaped cell at the bottom of the conceptacle, 
perhaps only because the border of this cell is lobed. 
Referring for the structure and development of the conceptacles of sporangia 
to THURET (I. c. p. 94, pl. 49 fig. 4—5) and Sots (I. c. p. 31, Taf. I, fig. 6—7), I shall 
as to the sporangia only mention that, after the division of the primary sporangial 
nucleus into four, a fairly long time elapses before the cell-division begins. A great 
number of sporangia with four nuclei situated about (not exactly) in a vertical 
series are therefore to be found (fig. 197 B). This was already observed by THURET, 
who remarks (1 c. p. 95): “La formation des cloisons est précédée de l’apparition 
d’espaces clairs qui occupent le centre des futurs spores 
(fig. 5)”. 
As elsewhere (comp. THURET, |. c. p. 95, Sos, L. c. p. 5), 
the sporangia-bearing specimens seem to be more frequent 
than the sexual ones also in the Danish waters, but I have 
not sufficient observations to affirm this with certainty. 
The species is, as elsewhere, rather variable, but cannot 
be divided into well defined varieties. When growing at 
low-water mark or in shallow water it is markedly pinnate, 
almost every joint bearing a pair of branches, and must Fig. 197. 
be referred to f. vulgaris Kützing (Tab. phye. VIII, p. 32, A ue 
Tab. 66 fig. 2; C. officinalis a, Areschoug 1. c. p. 562; C. offic. ECC es oes 
f. typica Kjellman, Alg. Arct. Sea p. 86 (114); C. offic. 7, 
Yendo 1902, p. 29, pl. VII, fig. 12, comp. Plate IV figs. 5—6). The specimens growing 
in deeper water are sometimes not much different from the ones just named, but 
are usually less branched and have longer joints. In f. vulgaris, the length of these 
does not reach 2 mm, while in the specimens from deeper water it not rarely 
reaches 3,5 mm, and even a length of 4,5 mm has been met with. In the extreme 
forms, the ramification is scarce and irregular, not pinnate, and the branches are 
often given off at various sides, though a tendency to branching in one plane is 
to a certain degree pronounced. Such forms may be named f. profunda Farlow 
(Mar. Alg. New. Engl., 1881, p. 179). In the Kattegat and the Samsø waters they are 
frequently coarser than the typical form, the joints being cylindrical, about 1 mm 
thick, and agree then fully with the description of f. robusta Kjellm. (1. c. p. 86 (114). 
This form has been collected in several places in the named waters in depths from 
10 to 19 meters (Plate IV fig. 8). 
The species is commonly spread in all the Danish waters with proportionally 
high salinity, including the Samso waters, where it is very common. It grows usually 
on stones, but may also be fixed to shells of molluscs (Purpura, Littorina, Buccinum, 
bivalves), on wood, and more rarely on Algæ (Furcellaria). It often forms associations 
D. K. D. Vidensk. Selsk. Skr., 7. Række, naturvidensk. og mathem. Afd. VII. 2. 35 
