[Vor. 8 
2 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
set of conditions, and these characteristics are inherited; and 
taken as a whole, they differ from those of any other race under 
similar conditions. 
For the determination of the species, forms, or races, there- 
fore, it is necessary to take into consideration all of the factors 
which have been referred to, and a comparison should be at- 
tempted only after careful observation of physiological and mor- 
phological characters, accompanied by extensive inoculation 
experiments. It is necessary to make comparative studies be- 
tween the original and reisolated strains, the latter being ob- 
tained from the plants used in the inoculation experiments. 
LrrERATURE REvIEW 
An adequate review of the literature concerning the diseases 
caused by Rhizoctonia may be had by recourse to the papers of 
Duggar (15) and Peltier (16). Especially is the early Euro- 
pean literature extensively reviewed in the paper first mentioned. 
Therefore I will permit myself only a brief review of some of the 
more important papers closely connected with my present in- 
vestigation. 
Since the first description of Rhizoctonia by DeCandolle in 
1818, many species have been described by different authors. 
The Tulasne brothers, who gave the most complete mycological 
account of the genus, classified all the forms then known as a 
single species, Rhizoctonia violacea Tul., reducing all other names 
to synonyms. Later Kühn described a new species on potato. 
This species, at least, he clearly distinguished from the — 
and he named it R. Solani Kühn. 
In the United States, since the first report of the disease of 
alfalfa mentioned by Webber, who considered it as identical 
with Rhizoctonia Medicaginis DC., many papers have been 
presented, such as those of Pammel (791), discussing its occur- 
rence on beets, and of Atkinson (92), reporting a sterile fungus 
on cotton seedlings, and later work showed its occurrence on a 
number of other kinds of seedlings. N evertheless, eredit for 
the comprehensive account of Rhizoctonia in America should be 
given to Duggar (799). He studied different types of plant 
diseases due to a common Rhizoctonia and showed that the beet 
fungus and carnation fungus were identical, although the special 
