Wager . — The Sexuality of the Fungi. 585 
resting spores are formed as intercalary swellings on the 
hyphae, or as terminal swellings on short lateral branches. 
In the young condition each resting spore contains two nuclei, 
which fuse together into one. The spores then become 
surrounded by thick cell-walls. Dangeard has also observed 
two nuclei in the young spores of Ustilago , and he thinks 
there are two in Urocystis. In Title tia he could not obtain 
stages young enough for the examination of the young 
spores. 
In the Uredineae the researches of Sappin-Trouffy 1 and 
Poirault and Raciborski 2 give a very full account of the 
cytology of numerous species of this group in all stages of 
development. In the aecidia the sporiferous filament contains 
two nuclei, which both divide at the same time, and by a 
successive series of parallel divisions a row of spores and inter- 
calary cells are produced, each of which contains two nuclei. 
Each aecidiospore thus contains two nuclei of different origin. 
The uredospores and teleutospores also contain two nuclei 
of different origin. These are regarded by Sappin-Trouffy as 
the last stages of a series of parallel divisions which started 
during the formation of the aecidiospores, and which now fuse 
together in the cell of the teleutospore into a single nucleus. 
This final fusion is regarded by Sappin-Trouffy as an act of 
fertilization, and the teleutospore is therefore equivalent to 
a zygote. 
Massee 3 described in 1888 the presence of sexual organs, 
antheridium and oogonium, in the Aecidium found on Ranun- 
culus Ficaria , but this has not been confirmed 4 . 
In the Basidiomycetes a fusion of nuclei has been observed 
to take place in the basidia of a large number of species 
1 Sappin-Trouffy, La pseudo-fecondation chez les Uredinees et les phenomenes 
qui s’y rattachent. Le Botaniste, iii, 1893-4. Sur la signification de la Fecondation 
chez les Uredinees. Le Botaniste, v, 1896-7, p. 32. Recherches Histologiques 
sur la Famille des Uredinees. Le Botaniste, v, 1896-7, p. 59. 
2 Poirault et Raciborski, Sur les noyaux des Uredinees. Compt. Rend. d. FAcad. 
d. Sci., cxxi, p. 308, and Jour. Bot., ix, 1895. 
3 On the Presence of Sexual Organs in Aecidium. Ann. Bot., vol. ii, 1888, p. 47. 
4 See Nypels, Bull. d. 1 . Soc. Beige Microsc., 1885, p. 70. 
