confluens and the Morphology of the Ascocarp . 381 
Oedogonium and multinucleated swarm-spores in Vaucheria 
As asexual reproductive bodies there is no reason for putting 
the swarm-spores of Oedogonium and Vaucheria in separate 
categories so far as their function is concerned. 
In the sexual reproduction of Pyronema , however, we have 
a combination of conditions in that the cells first fuse as 
individual units, and the nuclei then also fuse in pairs. The 
oogonium and the antheridium act as units in accomplishing 
the union and fusion of their respective protoplasmic bodies. 
There is a single receptive spot at the end of the trichogyne 
which functions for the entire contents of the oogonium. 
The oogonium of Pyronema in this respect is to be compared 
directly with the oogonium of Oedogonium . In the attraction 
which leads to the fusion of the antheridium and conjugating 
tube both organs may play a part, but they certainly act in 
this case in a fashion not to be distinguished so far as their 
nuclear content is concerned from that which brings together 
the conjugating tubes from the uninucleated cells of Spirogyra. 
The fact that there is no rounding up of an oosphere in the 
oogonium of Pyronema is plainly a secondary phenomenon. 
In the growth and metabolic processes leading to the differ¬ 
entiation of these cells as sexual organs, there is nothing to 
distinguish them from uninucleated eggs or sperm-cells. In 
the nuclear fusions, however, the nuclei, with perhaps a trace 
of cytoplasm for each, are the units which unite in pairs. 
This apparent return in so fundamental a process as sexual 
fusion to a condition in which the single nuclei act inde¬ 
pendently may suggest that the original primitive cell was 
uninucleated. The condition of the multinucleated proto¬ 
plasmic mass as found in the Siphoneae, for example, would 
then be regarded as a later modified development. If, 
however, as has been maintained by several authors l , the 
chromatin is distributed in the form of granules in the cell 
of a blue-green Alga, this fact must be regarded as evidence 
that the multinucleated cell may represent quite as primitive 
a condition as does the uninucleated cell. The behaviour of 
1 See Fischer, Cyanophyceen und Bacterien, p. 35. Jena, 1897. 
