124 ASCOMYCETES AND RHODOPHYCEA, 
a transverse wall, This end cell continues the development of the 
sporogenous filament, which in turn may fuse with other auxiliary 
cells. At 4, c, d the sporogenous parts of the fusion cells have given 
rise to branches which will produce either sporogenous filaments or 
spore fruits, as shown in Fig. 48, C, D. 
In all authentically known cases among the Rhodophycee@ the 
structure of the female sexual organ, the carpogonium, or we may say 
the odgonium, and the process of fecundation is essentially the same, 
but the development of the cystocarps from the fecundated egg differs 
widely in detail among the various genera.1 So far as is known the 
sporogenous filaments reach their highest development and complexity 
in Dudresnya, in which, as we have seen, the fusion of each of the 
sporogenous filaments takes place with a greater number of widely 
separated auxiliary.cells. In other forms, such as Callithamnion 
and Dasya (Oltmanns, ’98), in which only one or two closely ‘situ- 
ated auxiliary cells take part in the formation of the cystocarps, the 
sporogenous filaments may consist of only a few cells at most. In 
these cases we can scarcely speak of sporogenous filaments, but rather 
of sporogenous cells.? 
The relation which an auxiliary and a sporogenous cell sustain to 
each other is somewhat different in the several known genera. As 
already stated for Dudresnya, the sporogenous part of the fusion 
cell (Fig. 48, B, C, D) gives rise to the cystocarp, while in Gleosz- 
phonia capillaris (Oltmanns, ’98) the sporogenous cell, after the 
fusion of its contents with the auxiliary cell, may take no further part 
in the development. Its cytoplasm and nucleus pass into the auxiliary 
cell, and a cell-wall is formed separating the old cavity of the spo- 
rogenous cell from the auxiliary cell. From the auxiliary cell the 
cystocarp is now developed. A similar process takes place also in 
Callithamnion and Dasya. Although the behavior of the two cells 
in the last two genera named suggests a greater similarity to a real 
fecundation than in Dudresnya, yet the nuclei of the two cells never 
fuse, The sporogenous cell merely leaves its original abiding place 
to take possession of the auxiliary cell, using it as a basis from which 
to develop the spore fruit; for the nuclei of the auxiliary cell either 
disappear, or, if they persist, take no part in spore-fruit formation. 
The nuclei of all the cells of the spore fruit are descendants of the 
sporogenous nuclei, and are therefore sporophytic nuclei, while those 
of the auxiliary cells are gametophytic. The process occurring in 
1In addition to the authors mentioned above see also Philips, ’95, ’96, ’97, ’98. Osterhout, ’96, 
Hassenkamp, ’o2. 
2 See Oltmanns, ’98, Taf. v1, Figs. 11-20. 
