354 Harper.—Sexual Reproduction in Pyronema 
functional sexual cells are entirely emptied of their contents. 
They thus furnish very interesting evidence of the sexual 
nature of the fusions, in that they show that the cells con¬ 
cerned are incapable of further development if the fusion 
fails to occur. 
In view of what is described below of the fusion of nuclei 
in the oogonium this kind of evidence seems hardly necessary. 
Still, in discussing conidial fusions in the Smuts, Brefeld ( 5 ) 
has insisted especially upon the inability to develop further 
without fusion as a final test of the sexual nature of cells, 
and in these supernumerary antheridia we have a most 
striking example of this particular sort. Ultimately the 
contents of these antheridia disorganize into an undifferen¬ 
tiated deep staining mass which then becomes a prey to 
Bacteria and disappears. Brefeld doubtless overestimates 
the value of this sort of evidence, as I have endeavoured 
to show in another connexion above. 
How such waste of material comes to occur, when one 
might suppose the development of a single oogonium and 
antheridium together could be correlated from the beginning 
of the development of a fruiting cluster, is not so easy to 
understand. Such duplication of the antheridial branches 
never occurs in the Mildews so far as I have observed. It 
may be that this want of correlation is to be taken as indicat¬ 
ing that the sexual cells arise from rather widely separated 
branches of a mycelium if not from branches arising from 
different mycelia. 
The complete migration of the male nuclei into the oogonium 
represents the usual case ; still, it is not very uncommon to 
find a few nuclei left behind either in the antheridium or the 
conjugating tube. The significance of this latter condition 
will be discussed later. After the migration of the male 
nuclei is complete a wall is built across the base of the con¬ 
jugating tube, cutting off the oogonium once more as a single 
spherical cell. On the other hand the pore between the 
antheridium and conjugating tube remains permanently open 
and can be readily recognized in all the subsequent growth 
