LYMAN: STUDIES OF HYMENOMYCETES. 
197 
spiral enlarges to form a central cell (or cells) which becomes sur¬ 
rounded by a cellular cortex formed by the other cells of the spiral 
or by branches from below. The cortical cells become empty owing 
to the absorption of their contents by the central cell. Considerable 
variation is observed in this process, both in the central cells, and in 
the development of the cortex, which may be entirely absent. In 
Papulospora aspergillijormis Eidam, there is no distinction between 
cortical and central cells, and the primordium varies from an evident 
spiral or screw to a mere gnarled and knotted hypha. This latter 
method of formation closely resembles that seen in the basidiomy- 
cetous bulbils described in this paper (see p. 165 ). Zukal (’86) 
describes bulbils belonging to species of Peziza which originate from 
branching hyphae that become swollen, filled with protoplasm, and 
woven tightly together. The writer has under cultivation a species of 
bulbil found by Dr. Thaxter running over cultures of Cuban cotton 
flowers. It has the appearance of an erysiphaceous perithecium, but 
sections reveal no differentiation of the internal cells. It is formed 
from an interlacing weft of several different hyphae. 
The opinions held regarding the nature and the systematic affinities 
of these bulbils are very diverse. Karsten (’65) affirms that the 
central cell of Helicosporangium parasiticum sometimes functions as 
an ascus containing eight spores, and that the bulbil is a perithecium 
belonging to the Erysipheae. Eidam (’77; ’83), in studying what he 
supposed to be the same fungus, but which Karsten (’88) declares to 
be another species and names Baryeidamia, says that the central cell 
functions as a spore, not an ascus, and after comparing the bulbil to 
the perithecium of the Erysipheae and the spore balls of Urocystis, 
decided that the species should be regarded as a transitional form 
between the Ustilagineae and the Erysipheae. Harz (’90) regards 
the central cells in Helicosporangium and Papulospora as oogonia 
and creates the new order Leptoomycetes for these genera midway 
between the Oomycetes and the Zygomycetes and coordinate with 
them. 
In Papulospora aspergillijormis, Eidam (’83) believes that the 
bulbils are immature ascocarps which have stopped short of ascus for¬ 
mation, a view also held by Costantin (’88) in the case of Papulospora 
dahliae. In an article on the morphological value of fungus bulbils, 
Zukal (’86) comes to the same conclusion as Eidam, viz., that the 
bulbils he examined are not sclerotia, but ascocarps arrested in develop- 
