582 Wager . — 7 /^ Sexuality of the Fungi. 
variety of forms, states that in the Exoasci the mycelium 
becomes divided into cells, each of which possesses two nuclei 
and has the value of an oogonium. The two nuclei fuse 
together, and the cell becomes an ascus, the single nucleus 
of which divides to form the nuclei of the spores. In Peziza , 
Helvetia , Morchella , and Ace tabula the oogonium appears to 
be formed by apical fusion of two filaments, but this is not 
the correct interpretation, for Dangeard finds that it is an 
appearance brought about by the curving of a single filament. 
But he admits that it may be due to a terminal fusion of 
two filaments in the case of Bremascus 1 and Dipodascus 2 . 
The oogonia always contain two nuclei ; two gametes which 
fuse together to form the nucleus of the oospore. 
In Endocarpon miniatuni the papilla which forms the 
ascus contains two nuclei, and in Aspergillus glaucus the 
young asci contain two nuclei which apparently fuse together. 
Harper 3 shows that in Peziza Stevensoniana the ascus- 
nucleus is formed by a fusion of four nuclei. 
Dangeard also states that in the Truffle 4 the cells which 
form the asci contain two nuclei. These cells appear 
frequently to arise from the fusion of two different threads, 
but Dangeard thinks that, as in other cases, it may be simply 
due to the curving of a single filament. The two nuclei fuse 
together and at once begin to divide to form the spore nuclei. 
This fusion of nuclei in the ascus, or in the cell from which 
the ascus arises, is therefore apparently general throughout the 
group, although it is desirable that this should be confirmed, 
and is regarded by Dangeard as a true sexual process, a fusion 
of two nuclei of different origin into a single sexual nucleus. 
He is thus opposed to De Bary’s views as to the nature of 
the sexual process in this group. 
1 Eidam, Zur Kenntniss der Entw. bei den Ascomyceten. Beitr. z. Biol. d. 
Pflanzen, Cohn, iii, 1883. 
2 Lagerheim, Dipodascus albidus, eine neue geschlechtliche Hemiascee, Jahrb. 
f. wiss. Bot., xxiv, 1892. 
3 Harper, loc. cit. 
4 Dangeard, La Eruffe : Rech. sur son developpement, sa structure, sa repro- 
duction sexuelle. Le Botaniste, iv, 1894-5, p. 63. 
