202 SEAWEEDS 
layer of protoplasm covers them in turn. The cords 
which thus perforate the closing membrane establish 
a connection between adjoining cells, and though they 
do not admit of migrations of cell-contents in bulk, 
they may be used for the transference of dissolved 
. substances. However, it is supposed that their main 
function is to transmit dynamic influences, while the 
plates are the receivers of such stimuli. 
While the composition of the thallus of the Khodo- 
phycec is effected typically by the congenital union 
of cell-filaments in which subsequent intercalary 
divisions do not occur, it happens in isolated cases 
that such divisions occur in an exceptional manner. 
They occur with regularity in certain Corallines, and 
in the genus Nitophyllwm and its immediate allies, so 
far as the latter have been studied in this respect. 
As has been said, very diverse forms of thallus 
occur among the Rhodophycee, and these forms give 
us no definite clue to the systematic position of any 
particular form, since there may be associated very 
diverse formations of thallus with one common plan 
of formation of fruits, and a similar formation of 
thallus with diverse fruit characters. 
The Lhodophycee: are sexually reproduced by male 
cells produced in antheridia which fertilise female 
cells called carpogonia. The antheridia are of very 
various forms, always giving rise superficially to the 
special male cells which contain each a single non- 
motile pollinoid. These male cells are formed in 
great numbers together, and they originate from the 
terminal cells of longer or shorter branches of the 
thallus-filaments (Fig. 62,a). The clusters of such 
