of the Genus Doassansia , Cor mi. 35 
together into a hollow sphere, enclosing the hyphae at whose 
tips they are borne. Thin sections of the mature sori show 
that the ripened spores still remain attached to the hyphae 
from which they have arisen (Fig. 82). 
The spores do not separate from one another when the 
sorus is crushed, but germinate in position. From ten to 
eighteen hours after being sown in water the sorus is covered 
with a bristly mass of promycelia and sporidia. The pro- 
mycelium sometimes reaches a length of 16 ju, and is somewhat 
broader at the tip than it is where it arises from the spore. 
The sporidia are in whorls, from five to seven, on the broad 
blunt tip of the promycelium (Figs. 59 to 61), which is emptied 
of its contents and has septa (one or two), as mentioned above 
for other species. They are long and slender (2 6 n long by 
about 2 ix thick), pointed at both ends, and soon drop off. 
They are then found to be united in pairs at the base, some- 
times with a conspicuous conjugating tube (Fig. 62), but more 
often with almost none (Fig. 63). The germ-tube comes 
from the base of the pair of sporidia, as far as observed, but 
no germ-tubes of any length were seen. Deformities like the 
one shown in Fig. 64 were seen several times. 
The type of germination described above was found to be 
constant in numerous sowings made from fresh material in the 
months of June and July, both in 1889 and 1890. In these 
months the spores germinated freely a few hours after sowing. 
In August of both years the spores from fresh material ger- 
minated only scantily, and many of the promycelia failed to 
produce sporidia. Sowings made in September of both years 
failed to yield any results at all. 
Little need be said about the distinctness of this form. The 
structure of the sorus is entirely unlike anything described 
for any other member of the Ustilagineae. It seems neces- 
sary, therefore, to consider this species as the type of a new 
genus, and I take pleasure in dedicating it to Dr. Maxime 
Cornu, of Paris, who has so ably described and illustrated so 
many rare and curious Ustilagineae for us. 
Season. Lemna polyrrhiza begins to appear on the surface 
D 2 
