Wager . — The Sexuality of the Fungi . 595 
occurs ; that is to say, the ascogonial nucleus, although 
unfertilized, may still possess sufficient energy to produce the 
ascogonial filament, but the necessary stimulus for the pro- 
duction of ascospores must be brought about by the fusion 
of two nuclei in those ascogonial cells from which asci arise. 
We might also regard the fusion in the Basidiomycetes as 
having arisen in the same way, although in this group we 
have no indication of the primary sexual process. 
Groom 1 concludes that the nuclear fusions in question are 
asexual in character, and superposed upon and subsequent 
to the sexual act. They are concerned with the alternation 
of generations, and take place in a small fructificative 
degenerate generation. 
In the Uredineae and Ustilagineae we have no indication 
whatever of a primary sexual process ; but from the fact that 
these groups have become so completely parasitic — a parasitism 
of a peculiarly high order, as Marshall Ward 2 puts it, by 
which the organism has adapted its life to the habits of its 
host — we should expect also some modification in the sexual 
organs, so that here, as in the Basidiomycetes and Asco- 
mycetes, we are probably dealing with a degenerative nuclear 
fusion, not homologous with the sexuality of the Phyco- 
mycetes. 
It is not possible to come to any final conclusion as to 
the exact significance of these nuclear fusions in the higher 
Fungi. That they take the place of a sexual act, and lead to 
the reinvigoration of the cell, cannot, I think, be doubted. 
As Strasburger says : ‘ If the nuclei which fuse proceed 
from parts of the plant far removed from one another, one could 
see in this fusion a re-establishment of equilibrium necessary 
for the preservation of the species, which would be comparable 
in its physiological effects to fertilization V 
But even if the nuclei are found not to ‘ proceed from parts 
1 Groom, loc. cit. 2 Loc. cit., p. 296. 
3 Strasburger, Ueber per. Red. der Chromosomenzahl im Entwicklungsgang der 
Organismen. Biol. Centralbl., xiv, 1894, p. 864. See also Hartog, loc. cit., 
Q. J. M.S., p. 69. 
