92 SEAWEEDS 
branching filaments (Herponema), and this cushion- 
like thallus grows by the division of the peripheral 
cells. The assimilative filaments arise in centrifugal 
order, and grow by the division of their apical cells 
or their upper cells. 
The Reproductive Organs.—The unilocular spor- 
angia occur mostly singly, not in sori, but fairly 
evenly distributed over the thallus, and either as 
lateral out-growths of assimilative filaments or in 
place of these. In MMyrionema they spring directly 
from the basal cushion. They are relatively large, 
Fic, 22.—Chorduria divaricata. Transverse section of part of thallus, 
showing sporangia. Highly magnified. (After Reinke.) 
and vary in form from oval, obovate, clavate, to cylin- 
drical, with irregular lateral protuberances (Petro- 
spongium). The plurilocular sporangia are of diverse 
origin, as stated above, and have sometimes one, 
sometimes several rows of loculi. 
The genera composing the Chordariacce have been 
placed in many different orders by recent authors, 
and though no great degree of natural affinity can be 
claimed for the group as it stands, there are certain 
merits of simplicity mm its favour, as a provisional 
group at all events. 
