LL TER 
sporangia might suggest that they are transformed tetrasporangia which have been 
divided in a greater and indistinct number of cells. This supposition, however, is 
only little probable; at all events the transformation might then be supposed to 
begin at so early a moment that it was impossible to decide whether the young 
organ were really a sporangium. The sporangia are early distinguished by their 
regular outline and by the double firm membrane (fig. 222). The heaps of paraspores 
are a special form of vegetative propagative organs, more related to the vegetative 
cells than the sporangia. This 
conception is confirmed by the 
fact that transitional stages 
between the named organs and 
vegetative shoots frequently 
occur (fig. 221) and that they 
may, as named above, be re- 
placed by vegetative shoots 
(fig. 221 C—E). 
Tetrasporangia were found 
in some cases in paraspore- 
bearing plants, but in small 
number (Hirsholm, Frederiks- 
havn, Grenaa, Kerteminde, 
Skærbæk). They are usually 
A 
EIN | | Al II 
REN a | AI NN ZN placed on the first or on the first 
(LAGOS ER | \ \ \# \\ ve . 
N (( N\ A AV | A) and the second joint ofa pinnu- 
Py NON ) 3 > 
SN SSE NSS NS \\ { la. Curiously enough, intercala- 
=) = \ \\ 
= | LN = 
| im | | \ )\ 7 ; j 
3 | \ _ ry sporangia may sometimes 
D. SR ( | \ ‘a \E = FE 
N al \ be met with, arising from an 
\\ \ AN) intercalary cell in a pinnula 
€ \\ DNS | (fig. 222 D). In such cases one 
Fig. 222. of the spores is connected 
Callithamnion Hookeri. Parts of plants with tetrasporangia. In C the 
same branch bears a tetrasporangium and a heap of paraspores. D and 
E, intercalary sporangia. 4, B 145 : 1. C—E 200 :1. 
with the underlying cell by 
a pit, another spore with the 
cell above. Intercalary spo- 
rangia are hitherto unknown as a normal occurrence in the Ceramiaceæ, as far as I know. 
The specimens from all the localities with one exception, occurring in depths 
from 0 to 30 meters, most frequently from 0 to 10 m, agree with Kyrın’s f. éypica, having 
proportionally short cells, 2—3—4 times as long as broad, and well developed cortex 
on the principal axes. Specimens from YV in the Samsø area, 15 meters depth, 
remind one of f. elongata Kylin, 1. c. by its longer cells, 5—6 times as long as broad; 
but the pinnulæ are scarcely less diverging than in the typical form. The frond is 
more slender and the cortex is very feeble or almost wanting. These characters are 
perhaps caused by the greater depth at which the plant was found growing. The 
