the Cystoca7'p in Rhodomelaceae. 297 
Agardh (14) (Figs. 8, 9), which he states he observed in 
Polysiphonia violacea and other species of Polysiphonia , and 
also in Vidalia . They may be observed to become more and 
more attenuated and inconspicuous with the maturation of the 
carpospores, and it has occurred to me that a possible function 
is the supply of the plentiful mucilage which is found in the 
cystocarp when mature and which carries out the ripe spores 
with it as it escapes through the pore. That they play the role 
of a tapetum, and contribute to the nutrition of the spores, is 
hardly probable. Whatever the function of these paranemata, 
it is clear that they do not arise from the auxiliary cell, but 
from the subjacent central cell itself. They cannot therefore 
be regarded as sterile elements of the ‘ nucleus ’ ; they have 
an origin quite distinct. 
Polysiphonia nigrescens , Grev. 
Figs. 7, 8, 10, 11, 12. 
This species is common everywhere on the British coast. 
It belongs to that subdivision of the genus which Holmes and 
Batters describe as ‘ Polysiphoniae ecorticatae.’ The apical 
region is in spring densely clothed with leaves, as the monosi- 
phonous, freely-branched, hairlike appendages have been 
called, and it is modifications of these that bear antheridia 
and procarps. While it would be out of place here to discuss 
the external morphology of the Rhodomelaceae, it may be 
pointed out that Nageli and later writers have distinguished 
between two kinds of appendages in Florideae, leaves and 
branches; and Kny (15) has further discovered that, in some 
cases, in Chondria tenuissima for example, the same relationship 
exists between these appendages as exists in the higher plants. 
In Rhodomela subfusca these leaf-like appendages do occur, 
though not on the tufted procarp-bearing branches which 
I have described, where the procarps proliferate into ordinary 
branches, and would thus seem to be their morphological 
