conflttens and the Morphology of the Ascocarp. 323 
those which are purely vegetative. The conditions in Pyro- 
nema, as will be seen further on, make the true relations of the 
hyphae in question very clear. A real distinction between 
ascogenous and vegetative hyphae in all cases so far examined 
is in the size of the nuclei. Whether this difference will be 
found in forms yet to be investigated is of course entirely an 
open question. 
As to the actual conditions in Cladonia it is to be further 
noted that Wainio (41) claims to have found its trichogynes. 
Wainio and Krabbe agree that the podetium is a fruit and 
homologous with the apothecia of other Lichens so that the 
carpogonium should be expected to occur at the origin of an 
entire podetium rather than beneath each area of hymenial 
surface. It is in the very young podetia that Wainio claims 
to have found the trichogyne. 
Other authors have claimed for various Lichens that the 
apothecium develops without carpogonium or trichogyne, 
but the confirmation of Stahl’s work on the Collemaceae will 
certainly necessitate a reinvestigation of all these forms, on 
the possibility that the sexual organs have been overlooked, 
and it is not worth while to discuss them further from the 
standpoint of the existing observations. 
Baur’s (1) work on Collema crispum is of especial interest. 
He confirms Stahl’s (32) observations in all respects. Baur’s 
paper is only a preliminary one but he describes and figures 
carpogonia and trichogynes of the same type as those of 
Stahl. He finds that carpogonia, whose trichogynes show no 
spermatia, grow into vegetative hyphae which may become 
paraphyses if opportunity is given, thus, giving what amounts 
to an experimental proof of the necessity of fertilization by 
a spermatium if the asci are to be developed. In four cases 
empty spermatia were found attached to the end of the 
trichogyne, whose cells showed in these cases the same 
degenerative changes described by Stahl. The septa between 
the upper cells of the trichogyne were swollen, and the lower 
ones were still clearly broken down. Baur finds that the cells 
of the carpogonium are uninucleate at first, and obtained 
