DUDRESNYA. 125 
Callithamnion, Gleosiphonia, Dasya and others is after all not so 
extraordinary as it may at first appear, since the superior significance 
of the nucleus in all constructive metabolism of the cell has been 
thoroughly demonstrated. 
If the doctrine of Oltmanns be correct, and the facts seem to justify 
his conclusion, we have in the sporogenous filaments of Dudresnya 
and similar genera of the Rhodophycee a sporophyte, which, for the 
purpose of nutrition, fuses with auxiliary cells, and, because of the 
better nutrition, is capable of producing several spore fruits. The 
auxiliary cells must, therefore, be regarded merely as special brood 
cells, their fusion with the cells of the sporogenous filaments being 
homologous with the fusion of vegetative cells. 
As regards the existence of an alternation of generations in the 
Rhodophycee, there still remains the question upon which De Bary 
laid some stress, namely, that in the Rhodophycee, as well as in the 
Ascomycetes, there is no rounding up or separation of the egg as an 
independent cell in the oégonium, such as occurs, for example, in 
Coleochete, in the Bryophyta and Pteridophyta. In the second 
place the determination of the number of chromosomes in these gen- 
erations and the point in the life-cycle at which the numerical reduc- 
tion of the chromosomes takes place are factors, which, in the light of 
important existing theories, must be taken into consideration. The 
first of these questions may be of comparatively little importance, but 
an alternation of generations in the Ahodophycee will probably not 
be unqualifiedly accepted by some botanists until the question of the 
chromosomes is definitely settled, or until the full significance of the 
reduction is beyond question. 
A comparison of the process of fecundation and the immediate sub- 
sequent development in certain Ascomycetes and Flortdee reveals 
several striking parallels, or, shall we say, homologies. In the first 
place the female sexual organ in both groups is in all probability 
homologous. The carpogonium, or oogonium, of the /Yorzdee, with 
its large receptive part, the trichogyne, may be compared directly with 
the oogonium of the Discomycetes, e. g., Pyronema, and, perhaps, 
with the carpogonium of the lichen Collema. The presence or 
absence of a trichogyne is, moreover, of secondary importance, as this 
organ is purely an adaptation to peculiar environmental conditions. 
All representatives of this type of sexual reproduction agree in that 
the egg does not, by self-plasmolysis, separate itself as an individual 
from the odgonium. Whether the gametes be uninucleate or multi- 
nucleate is of little importance as viewed from a phylogenetic standpoint. 
