the Cystocarp in Rhodymeniales . 349 
mediate between the Sphaerococcaceae and Rhodomelaceae, 
and nearest to the tribe Calleblepharideae of the former 
family. 
It was therefore with considerable interest that I passed 
from an investigation of Rhodomelaceae to Bonnemaisonia 
asparagoides , the material for which I obtained from the 
Marine Biological Laboratory at Plymouth, where it had 
been collected and suitably preserved by Mr. George Brebner. 
Superficially, the plant presents in its external ceramidia, 
a strong likeness to the more slightly corticated forms of 
Rhodomelaceae. Even its marked monoecism finds its 
counterpart in Bolysiphonia byssoides , Grev. The ceramidia 
of Rhodomelaceae are however oblique, while those of 
Bonnemaisonia seem to be placed symmetrically on the 
end of the axis. The absence of tetrasporangia further 
distinguishes it from most Rhodomelaceae ; and, combined 
as it is with monoecism, recalls the condition in many 
Nemalionales. 
The investigation of the intimate structure of the young 
procarps is attended with considerable difficulty on account 
of their minuteness. After several trials, the most satisfactory 
method was found to be prolonged treatment with strong 
glycerine saturated with Hoffmann’s blue, and the subsequent 
examination of the procarps whole. 
I now propose to trace the history of the development of 
the cystocarp, as far as I have been able to decipher it. 
I omit all reference to the external morphology of the plant, 
which is well figured by Harvey, and to the anatomy of the 
vegetative parts which can be readily made out in material 
swollen in glycerine. Suffice it to say that the fertile branches 
occur on each side, alternately with the sterile branches, and 
so that a fertile branch is regularly opposite a sterile branch, 
a condition which occurs also in Ptilota and Plumaria among 
Ceramiaceae. When the branch which is destined to bear 
a procarp is six or eight cells long, and while peripheral cells 
are being cut off from the older cells in the plane of develop- 
ment of the plant, it is found that from the fifth cell onwards 
B b % 
