the Cy shear p in Rhodymeniales. 365 
of Schmitz) is ‘ so far removed from the carpogenous cell that 
fusion would hardly be possible except through the agency 
of an ooblastema-filament , 5 presumably meaning one of some 
considerable length, he is surely thinking of the remoteness 
of the supposed trichogynes of other branches. As I have 
already said, between the carpogonium of the true procarp 
and the carpogenous cell there is only the separation of the 
common cell-wall. 
Starting upon these two assumptions, ( 1 ) that all the 
branches bearing trichogyne-like hairs are true procarps, 
and ( 2 ) that all the carpogonia are equally remote from the 
carpogenous cell, both of which I cannot but regard as 
erroneous, Davis contends that the evidence favours the view 
that the favellae of Plilota are produced apogamously. In 
former papers (’96 a and ’96 b) Davis has expressed doubts 
upon the occurrence of a sexual process in Batvachospermum 
and Champia , and it would now seem that he is disposed to 
include many other Florideae in the same category. Into 
the discussion of the general question I do not propose to 
follow him further than to say that apogamy may yet be 
found to occur in Florideae, as in other groups of plants, but 
that there is no evidence in favour of the theory that it 
occurs in Ptilota. 
In further support of this view, however, Davis refers to 
the fact that no antheridial plants of Ptilota serrata or of 
Ptilota plumosa had been reported. For the antheridia of the 
Atlantic species he made a determined search, but without 
success. Upon reading this I decided to overhaul my pre- 
served material of Ptilota plumosa , which had been collected 
however for the sake of procarp-bearing plants. I had no 
difficulty in finding several fine antheridial plants which had 
been included unintentionally. The antheridia cover the tips 
of the branches, and correspond closely in appearance to the 
similar structures in Plumaria which have been figured by 
Bufifham (’90). As far, therefore, as the Ptilota plumosa of 
British waters is concerned, the theory of apogamy receives 
no support from the absence or infrequency of male plants. 
C C 2 
