352 
Phillips. — On the Development of 
Plocamium coccineum, Lyngb. 
This plant occurs commonly all round the British coast, 
and female plants with cystocarps in all stages of develop- 
ment may readily be collected during the early months of the 
year. Schmitz (’83) has given two figures of the early stages 
of the procarps, which are, however, insufficient for the 
complete understanding of the structure of the cystocarp. 
It was in order to obtain an insight into the history of the 
development of the fructification in a species of Rhody- 
meniaceae, that I undertook the examination of this readily 
accessible species. Schmitz and Hauptfleisch (’97) represent 
it however as a somewhat aberrant genus, presenting among 
Rhodymeniaceae the only case with a distinct axial row of 
cells. Its sympodial growth, and its stichidia with zonate 
tetraspores, undoubtedly mark it as a special form among 
Rhodymeniaceae, and may account for a cystocarpic structure 
somewhat different from that described by Hauptfleisch (’92) 
for Chylocladia and Lomentaria , and by Hauptfleisch (’92) and 
Davis (’96 b) for Champia. 
Plocamium coccineum has all its parts flattened in one 
plane, a circumstance which makes it easily mounted by 
collectors. It is on the edges of the young branches that the 
procarps occur in great numbers. The method, which I have 
now for some time resorted to, for the examination of the 
more solid Florideae, is to cut either the fresh or appropriately 
fixed material in frozen gum arabic, by means of a microtome. 
This method has, I find, been elaborated by Osterhout (’96), 
and employed with success by several investigators. 
The 3 -celled carpogonial branches arise in the cells inter- 
mediate between the large medullary cells surrounding the 
axis, and the small cells constituting the superficial layer 
(PI. XVII, Figs. 4 , 5 ). I was not able to discover that the cells 
giving rise to these branches stood in any definite relation 
by genesis to the cells of the axial row. The branches 
incline obliquely forwards, and occur in great numbers, more 
particularly on the ventral edges of the thallus. As they 
