547 
The specimens from the Danish waters to be described below agree so 
well with the Greenland specimens that I think they must be referred to the 
same species. In describing them the differing 
views of SCHMITZ and DARBISHIRE will be taken 
into consideration. 
The organism in question, according to LynG- 
BYE, always grows on the loose, sterile f. con- 
catenata of Ph. Brodiei, and the specimens examined 
by Scumitz were probably also growing on this 
host-plant. It is, in reality, very common on this 
form in the Danish waters, but it also attacks 
the typical, fructiferous Phyll. Brodiæi and has the 
same appearance in both cases. It is much branched, 
meee ‘ x 2 Fig. 531. 
the branches pointing in all directions. When Ceratocolax Hartzii, Vertical section of tetra- 
the branches issue near the base, the outer out-  SPore-bearing plant. From Lille Belt, April. 
30 : 1. 
line of the plant becomes nearly globular, the 
ends of the branches reaching about the same distance from the centre (fig. 531). 
In other cases there is a cylindrie stipe under the branched frond (fig. 530 A, B). 
The branches are repeatedly branched and often so crowded that the whole com- 
plex of branches is head-like. The branches are cylindric or a little complanated 
but never flat, often irregularly curved; in spring they usually end in a globular 
Fig. 532. 
Ceratocolax Harlzü. A, sec- 
tion of cortex ofthe lower 
portion of the frond. B, 
medullar cells showing 
nuclei and chromato- 
phores. 625 : 1. 
swelling, while later in the year the tips of the branches 
are not swollen but often much branched (fig. 530 B, C). 
The colour of the plant is pink, in particular in spring, 
or somewhat varying from yellowish to greenish according 
to the season and other external conditions, like that of the 
host-plant, but usually brighter, and brighter toward the tips 
of the branches. 
The structure of the frond is somewhat similar to that 
of Phyllophora Brodiei, but the consistency is softer. The 
cortex consists of outward directed cell-rows the innermost 
cells of which gradually pass into the medullary tissue. In the 
lower, sterile parts of the branches, the cortex is comparatively 
thick, consisting of regular parallel cell-rows, up to 6—8 cells 
long (fig. 532). In the upper, fertile regions, the cell-rows are 
shorter and not so densely crowded; the intercellular substance 
is here especially soft, and the arrangement of the cells is 
therefore often disturbed by microtomizing owing to the swel- 
ling of this substance (comp. figs. 537—539). The cortical cells 
are connected by primary pits in the transverse walls, but 
secondary pits may also occur in the longitudinal walls (fig. 532 A). The cells 
seemed often to contain a single calotte-shaped chromatophore, but in well-fixed 
70* 
