the Cystocarp in Rhodomelaceae . 
299 
Polysiphonia fastigiata (Roth), Grev. 
Fig. 9. 
This species is readily identified as a common epiphyte 
on Ascophyllum nodosum , Le Jol., and is probably on this 
account usually selected for description as a type of the 
Florideae. It comes very near P. nigrescens by general 
consent, but differs from that species in the total absence 
of leaves. The development of the cystocarp is closely 
comparable with that of P. nigrescens , but is somewhat more 
difficult to follow on account of the greater compactness 
of the procarp. When the sporogenous cell has been seg- 
mented off, the first sporigerous filament consisting of two 
cells appears in line with the sporogenous and the auxiliary 
cells, presenting the appearance of three equivalent sporo- 
genous cells. The whole contents of the procarp may readily 
be squeezed out by gentle pressure in this species, and as the 
cells are held together by the pit-connexions, it is possible 
to make out the relationship, though the disturbance makes 
it occasionally puzzling. It is the pit-connexion with the 
central cell which gives way on this treatment. When from 
a fertilized procarp more than eight cells are thus squeezed 
out, in addition to the remains of the carpogonial branch, it is 
due I believe to the inclusion of rudimentary sporigerous 
filaments. 
I have been unable to trace the sterile cells in maturer 
cystocarps. They probably undergo absorption by the sporo- 
genous cells during the spore-formation. 
The paranemata are very clear and may be noticed even 
after the discharge of the spores. 
During the enlargement of the cystocarp, the parietal cells 
bud to form an imperfect cortex, closely encased in the old 
cuticle, but the pericarp cannot be said to be two cells thick 
continuously. 
