Annals 
of the 
Missouri Botanical Garden 
Vol. 8 FEBRUARY, 1921 No. 1 
STUDIES IN THE PHYSIOLOGY OF THE FUNGI 
XII. PHYSIOLOGICAL SPECIALIZATION IN RHIZOCTONIA 
SoLANI KÜHN 
TAKASHI MATSUMOTO! 
Formerly Laboratory Assistant, Missouri Botanical Garden 
INTRODUCTION 
The study of the diseases induced by Rhizoctonia has been 
undertaken by many investigators in different countries since 
the first report of the occurrence of this organism in 1728, in 
France. Nevertheless, the occurrence of this fungus on such a 
diversity of host plants and the possible existence of distinct 
forms or races within the species suggest that there are many 
phases of the subject still requiring extensive investigation. 
The chief object of the present investigation was to make 
a comparative study of such strains of Rhizoctonia Solani Kühn 
as could be obtained from different disease types of the same 
host. 
It is a well-known fact that a culturable fungus may exhibit 
considerable differences in morphological characteristics and in 
physiological behavior under the influence of changes in the 
culture media or other environmental conditions. On the other 
hand, within the species there may exist forms or races which 
in no sense represent the effects of simple environmental factors. 
These races show more or less distinctive and constant morpho- 
logical and physiological characteristics under any particular 
1 Now Professor of Botany, Imperial College of Agriculture and Forestry, Mori- 
oka, Japan. 
Ann. Mo. Bor. GARD., Vor. 8, 1921 (1) 
