26 
Mycologia 
There are three possible explanations for these exceptions. First, 
as has just been mentioned, the life history may have become short- 
ened or it may be incompletely known. From the survey of the 
studies made, this appears to be the most probable condition ex- 
isting where parallelism fails to appear. Second, the supposed 
conidial and ascigerous stages of a species may have no connec- 
tion. Numerous instances have been brought to light which show 
that the original work on the basis of which genetic relationships 
have been accepted was erroneous. Undoubtedly there are many 
such assumed connections in this class of fungi. Third, the hy- 
pothesis falls down completely in certain cases. 
While it cannot' be said, with our present knowledge of many of 
the Ascomycetes, that all cases can be made to conform to this 
theory, yet there seems to be enough evidence presented to show 
that such a distinct similarity is the rule and that dissimilarity is 
the exception. 
Summarizing these observations, it would seem that among the 
strictly monomorphic conidial forms of Ascomycetes a rather 
constant parallelism exists between conidia and the ascospores of 
the alternate stage; that when one- and two-celled conidia occur, 
as in V enturia and other genera, the ascospores of the alternate 
stage are generally two-celled ; that when the conidia are one- 
celled and the ascospores two-celled the conidia may in some cases 
behave as a two-celled spore when they germinate. 
Among the pleomorphic conidial species the same likeness prob- 
ably exists between one of the conidial stages and the ascospores 
of the alternate stage. Further, it seems probable that when 
parallelism fails to appear it may be due to abbreviation or to our 
incomplete knowledge of their life history. 
A study of the nuclear phenomenon of the conidial stages dur- 
ing spore formation and germination would undoubtedly throw 
much light upon the whole subject. 
The important feature of parallelism as herein outlined is the 
assistance given the mycologist and plant pathologist to antici- 
pate with some accuracy the probable relationship between co- 
nidial and ascosporic stages. 
Thanks are due Professors R. A. Harper and F. D. Kern for 
