VARIATIONS IN PLEURAGE CURVICOLLA (WINT.) KUNTZE 
J. L. Weimer 
Introduction 
The fact that one strain of a fungus may differ considerably from an- 
other strain within the same species coming from a different source, growing 
on a different substratum, or subject to other stimuh, has long been known. 
Yet the knowledge of the extent of such variations found recorded in liter- 
ature is scattered and comparatively meager. This lack of exact data on 
the amount of variation, both morphological and physiological, within the 
species has led to considerable confusion and often makes it practically im- 
possible to decide whether or not the fungus at hand belongs to a previously 
described species. It is only by the careful observation and study of a 
fungus species under the influence of different environmental conditions 
that its limitations can be determined. Too often fungi are described 
from specimens from a single source and on but one host or substratum, 
with the result that some of their characteristics may be overlooked. Later 
another worker obtains a strain of the same species from another source 
or under different conditions, notes rather striking differences not' men- 
tioned in the original description, and gives it a new name. As a result an 
organism may receive many names, and only when the group is carefully 
monographed is it found that these are but variations of one and the same 
species. The chaotic condition produced by the indiscriminate product- 
ion of new species was discussed at length at a meeting of the Botanical 
Society of America in 1908 and the discussion was published in the Ameri- 
can Naturalist^ of the same year. 
The purpose of this paper is to record certain variations noted in a 
strain of Pleurage curvicoUa with the hope that these may add something 
to the present knowledge of the extent to which individuals of a single 
species may vary and yet not afford sufficiently different morphological 
characters to justify the making of a new species. 
Source of the Organism 
The strain under discussion first appeared in 19 18 as a contamination 
in a culture of Sphaeronema fimhriatum which had been isolated by Dr. 
L. L. Harter in 1912 from a sweet potato affected with black rot, and which 
had been in the laboratory continuously since that time. Single ascospore 
isolations were made, and the organism thus obtained was used in the work 
here recorded. 
1 Amer. Nat. 42: 217-281. 1908. 
406 
