142 STEVENS: PREVALENCE OF ENDOTHIA GYROSA 
tural conditions to erosion is aptly described by Spillman (9, p. 260) 
as follows: 
The northern half of the country has always been more or less covered with 
various grasses. These have prevented soil erosion except in small isolated areas; 
but in the South where a single-crop system with clean culture has been the rule, 
and where in consequence, the soils have been left bare during the winter, soil erosion 
has been an important factor, especially where the land is more or less rolling or hilly- 
The effect of the cattle industry in increasing the opportunity 
for infection and thus in all probability the abundance of the 
fungus in southern Indiana and Ohio has already been mentioned. 
And from the beginning of our collecting, the unfenced public 
squares of the southern towns where stock is permitted to graze 
have proven most favorable localities for the growth of Endothia 
gyrosa. 
In brief, the writer believes that while the occurrence of E. 
gyrosa may be limited by climatic factors which are not yet deter- 
mined, its prevalence in the southeastern states is caused by the 
great opportunities for infection in that region, due to the com- 
bined influence of host, soil, climatic and cultural conditions. 
SUMMARY 
Endothia gyrosa, which has a wider known range in America 
than any other species of the genus, is undoubtedly indigenous, 
having first been collected by Schweinitz nearly a century ago. 
Although found in widely separated localities in the United 
States it is abundant only in the Southeastern States. Range 
maps of this and other American species of Endothia based on two 
years’ collecting by Dr. C. L. Shear and the writer have already 
been published. 
Inoculation experiments conducted in 1914 and 1915 showed 
that E. gyrosa would under certain conditions grow and winter 
over beyond the northeastern limits of its known range as well 
as within the region where it is abundant. 
These inoculation experiments emphasized the importance of 
the water supply and of the condition of the host in the growth of 
the fungus. 
E. gyrosa grows most readily on injured tissue which does not 
dry out immediately but remains living for some time, such as 
stubs of cut limbs or injured roots. 
