1062 The American Naturalist. [December, 
organ, the ascus, which has given to the order its name, Asco--- 
mycetes. This name has, however, been used in a rather more 
restricted sense than that of Brefeld. This is due to the fact that 
the characteristic of the group has been considered to be the 
ascus fruit, and not the ascus itself. But here, as in the Basidio- 
mycetes, the fruit body is a secondary development within the 
group, subsequent to, or at most contemporary with, the differen- 
tiation of the ascus. Mosphologically, the ascus is to be regarded 
as a reduced and definite sporangium whose form is constant, at 
least within the limits of the species, and whose spores, typically 
eight, are in most cases definite and constant in number. Inter- 
mediate conditions between the indefinite and definite extremes 
are distinctly to be recognized. The numerous and striking sub- 
divisions which occur in the spores of the Ascomycetes, so useful 
systematically that they form the basis of Saccardo’s carpologic 
system, are regarded by our author as germination phenomena, 
analogous to those seen in Dacryomyces and the Tremellinee, 
which have become pushed forward into the earlier stages of 
spore development. 
From the great body of the Ascomycetes which have a well- 
developed fruit body, and are called by him Carpoasci (constitut- 
ing the whole of the order, according to the limitations of 
DeBary), Brefeld separates the forms included under Endo- 
myces, Taphrina and Exoascus, and Ascocorticium nov. gen., 
as Exoasci. The members of this group, corresponding to the 
Tomentelleze among the Basidiomycetes, have their asci produced, 
free and naked, directly from the mycelium. The Carpoasci 
include angiocarpous forms, the Gymnoasci, Perisporiacee 
(including Tuberacez), and the Pyrenomycetes ; and hemiangio- 
carpous forms, grouped under the Hysteriaceæ and the Disco- 
mycetes. One family of the latter, the Helvellacee, may yet 
prove to deserve separation from that group. The early stages 
of its members are unknown, but they may be found to be truly 
gymnocarpous. 
If we go back once more to the sporangium of Mucor, we 
may trace a very instructive series up to the ascus fruit of the 
Carpoasci. In Rhizopus we have a plant which differs from 
Mucor essentially in producing from a given* region several 


