252 MONOGRAPH OF THE LABOULBENIACE.E 
in any attempt to trace the homologies of the ascus or the derivation of the group of 
Aseomjcetes in general. 
It is not my intention in this connection to enter into any detailed discussion of 
the several theories which have been advanced in regard to these matters j yet they 
cainiot be allowed to pass unnoticed. In brief, it may be said that, as regards the 
primary origin of the Ascomycetes, authorities seem generally agreed in deriving 
them, in an ascending series, from the Pliycomycetes ; but in the discussion of the 
homologies of the reproductive organs in either case, the agreement has not been 
so striking. De Bary, as is well known, relying in a great measure on his observations 
in regard to the development of Sphserotheca, as well as on the account given by 
Eidam of his genus Eremascus, finds little difficulty in houiologizing (with his usual 
judicious cautiousness of statement) the asci of these genera with the oo^-onia of 
the Phycomycetes ; while their sexual derivation was further substantiated through 
the studies of Janczewski and others on Ascobolus, by those of Kihlman and others on 
Pyronema, by those of Stahl on the Collemaceae, as well as by further observations 
which need not be here enumerated. In later years there has been a reaction from 
for the most part due to the very imp 
of Brefeld. This writer, by 
g, researchc 
of a large amount of wholly negative 
pre 
vidence, having discarded as without significance the positive evidence just referred 
ents an argument from which he concludes that although the Ascomycete; 
have originated from the Phycomycetes, they have lost all traces of sexual organs 
According to this view, the ascus is assumed to be merely a modified non-sexual sno 
homoloorous with the 
"O"""-'^ "^"^vyix^" 
sporangia of the Phycomj'cetes ; and 
attempt is made to substantiate this assumption by the citation of a series of 
examples which, in his opinion, illustrate the actual process of evolution by which 
this transformation has been brought about. 
In stin more recent years, observations made by Dang^ard on the phenomena of 
prior to spore formation, have led 
oosporic sexuality, thus expressed, is general among the 
fusion in the Ascomy 
believe that 
higher fungi, including the group in question ; a view which, for reasons that need .. ^ 
here be considered, does not seem to call for serious consideration. 
It is thus apparent that the question under discussion has resolved itself into the 
phyllogeny, not of the Ascomycetes, but of the ascus ; one " school " assertinn- its non- 
sexual character, the other the reverse. Supporters of the former contenlion, like 
N an Iieghem, for example, seeing in the trichogyne of Stahl a remarkably developed 
ventdatmg apparatus," or in the « carpogoniun, " of Ascobolus or Pyronema, a 
