316 BOTANICAL GAZETTE [APRIL 
Nemalion are those of the so-called oosporic type of reproduction, and 
are not essentially different from the state of affairs described for such 
a type as Coleochete. The differences between the two forms are 
concerned with the morphology of the antherozoid and oogonium (the 
latter, by custom, termed a carpogonium in Nemalion), and not with 
the physiology of the sexual act. 
But excepting Nemalion and certain related forms that for the most 
part have not been studied in detail, the other groups of red alge pre- 
sent various peculiarities. A few examples will be sufficient to illus- 
trate these curious conditions. 
In certain species of Callithamnion there are two auxiliary cells, 
each giving rise to a separate and independent favella of spores. The 
carpogonium with its trichogyne occupies a position between the two 
auxiliary cells, but is not connected with either. Indeed, the three 
structures may be separated from one another by a considerable space. 
How is the stimulus of a sexual act, taking place in the trichogyne = 
carpogonium, to be transmitted to the auxiliary cells and excite le 
development into favella of spores? Oltmanns reports some crit 
observations upon this problem which for a long time has bees bes 
perplexing, and they will be referred to in another part of this aii 
Dudresnaya furnishes the best known and perhaps most ase 
peculiarities. Here the auxiliary cells are situated upon widely ni 
rated filaments or branches of the frond and often far removed ff 
ative filaments and 
ments that grow among the loosely arranged veget 
§ ong A 8 ‘nts the two ele- 
come in contact with the auxiliary cells. At such pi 
ments fuse so that the cell-contents mingle, and here are develope 
glomerules of spores. Where does the sexual act take place pee 
resnaya, at the points of fusion between the filaments a ie 
cells, or previously in the carpogonium? If fertilization © of the 
plished in the trichogyne or carpogonium, what is the meaning 
second act of fusion at the auxiliary cells ? era that 
There are also a number of instances reported, from a i 
- 
: ae the Gigart- 
are not closely related to one another, in such ae auxiliaty 
nacee and Rhodomelacee. In these there is pe cture fuses 
cell close by the carpogonium, with which the latter ee ge 
directly or by means of a connecting tube. 
this single auxiliary cell, and what are the cytologica 
cerned with the act of fusion ? 
l phenomen® ~. 
