290 
WILLIAM H. BROWN 
the variety inigneum. Seaver found that his strain always produced 
abundant crops on soil or leaf-mold which had been sterilized by 
heating to high temperatures or by steam heat if under sufficient 
pressure, while he was not able in a single case to produce more than 
a beginning of growth on unsterilized soil. There is nothing to indicate 
that Seaver found this strain to be hydrophytic and the writer has 
found that it grew very vigorously on the outside of clay flower pots 
which stood in an ordinary laboratory room where the air frequently 
became quite dry. The differences in the conditions of sterilization 
and moisture under which the strains, described by Harper, Kihlman, 
and Seaver, were grown would seem to indicate that in Pyronema, 
as in Puccinia graminis Pers. (Eriksson, '96), there may be different 
physiological varieties which are entirely similar morphologically. 
It is, of course, uncertain as to whether these strains are permanently 
different or could be changed from one to another by gradually chang- 
ing the environmental conditions. There is, however, nothing to 
indicate that the latter is the case. 
In view of the experiments of Van Tieghem ('84), who found that 
the course of development of Pyronema was markedly influenced by 
the external conditions, it seems altogether likely that the growth of 
this plant under different physiological conditions might produce 
different morphological varieties and this may have been the origin 
of the variety inigneum. 
The variety inigneum was found about the first of April, 1908, 
growing on a flower-pot in the botanical laboratory of the Johns 
Hopkins University. The ascocarps were produced to some extent 
on the soil inside the pot, but were much more abundant on the pot 
itself, where they formed large patches on both the inner and the 
outer surfaces. The pot on which these were found had been used 
for growing fern prothalli and had been watered constantly since 
some time during the previous October. A large number of the pots 
used in the laboratory had been sterilized early in October but it is 
uncertain as to whether or not this particular one had been. It is 
certain, however, that since that time, it had not been subjected to 
any conditions approaching sterilization. 
As soon as the fungus was found, the pot on which it was growing 
was transferred to another room and kept watered for the next two 
months, during which time ascocarps continued to be produced in 
large numbers. They were, however, never as abundant in subsequent 
