304 
ginating without doubt in the following way: the first uninucleated apical cell (comp. 
fig. 210) has produced two uninucleated segments each developing into a procarp. The 
procarp of the undermost procarp protruded obliquely at the side. 
The development of the gonimoblasts has been described by Ky in (1. c.). The 
ripe carpospores contain one large nucleus (fig. 212). During the development of the 
cystocarp a number of involucral branches grow out under its base; there are usu- 
ally 3 or 4 more rarely up to 8. 
When sexual organs are present, they almost always occur on the same plant 
and further in combination with sporangia: the three kinds of reproductive organs 
are as a rule to be found in the immediate neighbourhood of each other on the same 
system of branches or branchlets, in various combinations. Usually the procarps are 
terminal in such complexes of branches, and branchlets bearing antheridia or spo- 
rangia are given off under them. A cytological study of such plants is much needed 
(comp. Kyrın 1916). 
The species is widely distributed in the Danish waters except those with 
slightest salinity (the Baltic around Moen and Bornholm and the Sound south of 
Helsingør). It occurs scantily in the Limfjord but has otherwise not been met with 
in the fjords except ihe Isefjord where it has been found in the entrance. It attains 
its greatest development in the North Sea and the Skagerak where it has been found 
in almost all the places investigated and frequently in great abundance. It occurs 
here in dense tufts up to 5 cm high and may be referred to f. Turneri; it is usually 
fructiferous in summer and frequently bears sexual organs together with sporangia. 
Similar specimens are found in the Northern Kattegat, scarcely however exceeding 
3 cm in height, and transitions to f. roseola are frequently met with, the sporangia- 
bearing branchlets bearing only a very small number of sporangia. In the more 
southern waters the species is usually sterile, even in summer; in some places, how- 
ever, it has been found with tetraspores, but nowhere with sex organs (except once 
at Helsingor), The branches are rarely or not at all opposite and the sporangia are 
placed singly or in pairs on the pedicels. Also in the southern waters transitional 
forms may be met with: e. g. specimens collected at Lohals in Sh have partly nu- 
merous opposite branches and well developed corymbiform sporangial clusters. 
Spermothamnion repens grows epiphytically on various Algæ, principally on Fur- 
cellaria fastigiata, also frequently on Phyllophora membranifolia, Ahnfeltia plicata and 
Corallina officinalis, further on several other Florideæ, on Fucus serratus and Lami- 
naria hyperborea and digitata, and finally it has been met with growing on Bucci- 
num undatum. It is perennial, but most of the upright filaments perish in the au- 
tumn, and the tufts are therefore only 2—10 mm high in winter. It is fructiferous 
only in summer, June to September (October). Ripe sporangia have been found in 
all these months. ripe cystocarps only in July to September. The species has been 
met with from low-water mark to 31 meters’ depth (North Sea); in the Kattegat it 
has been observed down to 25 meters’, in the more southern waters only to 13 
meters’ depth. 
