399 
Sporangia containing more than four spores were met with as rare exceptions 
in Spermothamnion repens and Seirospora Griffithsiana. 
6. Paraspores have been met with in the following species occurring in the 
Danish waters: Callithamnion Hookeri, Plumaria elegans, Seirospora Griffithsiana, Ce- 
ramium diaphanum, C. strictum, C. Deslongchampsü, C. vertebrale. According to 
Schmitz and SCHILLER (1913) they occur in the Mediterranean also in Antitham- 
nion Plumula. 
Paraspores are never produced in sexual plants. The paraspore-bearing plants 
often bear only these organs, but in all the species in question tetrasporangia are 
sometimes produced by the same plants, most frequently in the Ceramium-species. 
In Antithamnion Plumula SCHILLER found at Triest paraspores in numerous plants 
which all bore tetrasporangia too. This author tries to show that the paraspores 
in the Ceramiaceæ must be interpreted as modified tetrasporangia, relying on the fact 
that they always occur on tetrasporiferous plants and that they often have the same 
position as the tetrasporangia. This interpretation is certainly warranted for the 
polysporangia in Pleonosporium which wants typical tetrasporangia, but it cannot 
be accepted for the true paraspores here in question. The paraspores are at their 
first appearance decidedly different from tetrasporangia. Whereas the latter have an 
especial form and early show a firm two-layered cell-wall, the shape of the young 
heap of paraspores is more indefinite, they have a homogeneous more soft wall and 
the content in an early stage is not more coloured than the vegetative cells, in Plu- 
maria even decidedly less coloured, while the young sporangia are deeper coloured 
than the vegetative cells. Further, the position of the paraspores is not always the 
same as that of the tetrasporangia, in particular in Ceramium which is also admitted 
by SCHILLER (1913 p. 149). According to this author two sorts of “paraspores” 
occur in Ceramium 1° polyspores and 2° true paraspores. The first named organs 
are produced in the cortical bands, e.g. in C. strictum and C. Deslongchampsii and 
according to SCHILLER arise from “eine mit einer Tetrasporangienmutterzelle iden- 
tische Zelle’ I. c. p. 11). I have not observed these organs that seem to be similar 
to the polyspores in Pleonosporium. The second sort of paraspores develop in a quite 
different manner. In C. strictum described by SCHILLER they arise at the tips of the 
branches, all the young cells, even the central cells, being transformed into paraspores. 
In C. diaphanum and C. strictum from the Danish waters the paraspores arise, as 
shown by HENN. PETERSEN, only from the peripheral cells in the cortical bands, 
most frequently near the upper edge of the bands, often from the marginal cells 
(HENN. PETERSEN 1908 p. 52, 57, figs. II, IV, comp. my fig. 313). When SCHILLER, 
in order to show the derivation of the paraspores in C. sirietum from the tetrasporangia, 
only adduces the facts that they only occur in the tetraspore-bearing plants, and 
that the tetraspore-formation decreases in the same degree as the paraspore-form- 
ation increases, it must be said that this proof is quite insufficient. The fact that 
? ScHILLER’S C. strictum is certainly not the true C. strictum Grey. et Harvey. Dr. HENN. PETERSEN 
thinks that it is rather a form of C. diaphanum. 
o1* 
