The Reproduction of Ahnfeltia plicata. 23 
complex of cells arising from the generative cells must be 
considered as representing a new generation, comparable 
to the sporophytic generation (Actinococcus) of Phyllophora 
Brodiæi (comp. K. ROSENVINGE 1929) though there are es- 
sential differences. The Actinococcus generation arises in a 
fertile segment of the frond from an auxiliary cell, in a 
similar manner to a gonimoblast, which process, according 
to H. CLauszEn (1929) and Kyrın (1930 p. 27) must be 
supposed to have been preceded by a fertilisation, so that 
the nuclei of the sporophyte are diploid (8 chromosomes) 
whereas those of the gametophyte are haploid (4 chromo- 
somes). The secondary (fertile) nemathecial cell-rows in 
Ahnfeltia arise from several, perhaps numerous, generative 
cells produced in particular organs: the primary nema- 
thecia. The question then arises, what morphological 
significance must be attributed to the generative cells. Some 
would perhaps prefer to consider them as organa sui 
generis without any relation to other reproductive cells in 
the Florideæ, but this view, I think, is not satisfactory. 
The young groups of generative cells offer some resemblance 
with the incompletely developed procarps which occur so 
frequently in Phyllophora Brodiwi (K. ROSENVINGE 1929 
fig. 10) and it appears not unlikely that they are, like 
these, reduced procarps, though differentiated carpogonia 
and auxiliary cells have never been ascertained. If this 
interpretation is right, it must be assumed that there are 
a great number of starting points for the secondary nema- 
thecial filaments in the same nemathecium, though perhaps 
not so many as might be supposed because several of the 
cell-groups may be produced by the horizontally running 
cell-rows (comp. fig. 6) and a number of the cell-groups 
do not perhaps produce nemathecial filaments. By this 
