the Cystocarp in Rhodymeniales . 363 
a trichogyne-like process. Of these branches one is terminal, 
and is more an axial structure than a branch, being a direct 
continuation of the apical cell : including the cell from which 
it is derived, it is invariably a 3-celled structure. The sub- 
apical cell gives rise to two branches, one above and one 
below, each of them being 3-celled. The peripheral cell also 
gives rise externally to two filaments, one 4-celled and one 
3-celled. The order in which they have been now enumerated 
is not, however, the order in which they arise. The first to 
arise, it is agreed, is the 4-celled external branch. The 
carpogenous branch is also derived from the same peripheral 
cell from which originate the two external branches. 
All these five filaments, the terminal, two lateral, and two 
external, are considered by Davis to be equally carpogonial 
branches. Before the publication of this view, I had already 
in the summer of 1896 examined Ptilota plumosa , and had 
come to the conclusion that only one of them is a true carpo- 
gonial branch, the other four being mere vegetative filaments 
terminating in hairs. To the latter I had already given in 
my notes the name ‘ pseudo-trichophores.’ Upon reading 
Davis’s very clear description, I again examined the procarps 
of Ptilota plumosa , and extended my observations to Plumaria 
elegans , with the result that my earlier opinion was confirmed. 
The 4-celled external carpogonial branch is, according 
to my view, the only true procarp present, the other four 
being vegetative structures. My reasons for holding this view 
I submit below. 
1. In the first place, this external 4-celled branch has 
greater morphological fixity than any other branch in the 
group. It is the first formed, and the only one which is 
invariably present. Davis alludes to the occasional sup- 
pression of the second external branch, and of one or both 
of the lateral branches. In Plumaria elegans , which I have 
found to correspond closely with Ptilota plumosa in the 
general morphology of its procarpial branch, all the filaments 
other than the 4-celled external branch may remain at times 
undeveloped, and it is rare to find the whole five ever 
