216 THE AMERICAN NATURALIST. [VoL. XXXII. 
The higher fungi, including the Basidiomycetez, show this infre- 
quence of individuals still more emphatically ; the Gasteromycetez 
are ordinarily infrequent, with now and then an exception, in favor- 
able periods, as when /thyphallus impudicus springs up in great 
abundance; the Hymenomycetez are normally rare, although the 
number of species is fairly large. 
Apparently this relative infrequence of the fungi is due to the 
greater aridity of soil and air, resulting in less favorable conditions 
for the germination of the spores, as well as for the subsequent devel- 
opment of the plants themselves. 
B. M. Duccar anD F. C. Stewart: Different Types of Plant 
Diseases due to a Common Rhizoctonia. — Rhizoctonia was established 
by De Candolle, in 1815, as a generic name for certain sterile fungi. 
Many species have since been described, all of which may be sub- 
terranean parasites. There is no certain evidence connecting these 
forms with fruiting stages. Studies in plant diseases during the past 
few years have brought together some very different types of disease 
due to Rhizoctonia, viz.: (1) damping off of seedlings of many 
kinds ; (2) a rot of radishes ; (3) a root-rot of beets; and (4) a stem- 
rot of carnations. Experiments have proved conclusively that the 
root-rot of the beet and the stem-rot of the carnation are inter- 
changeable, and indicate that the sterile damping off fungus is also 
very probably the same species slightly modified physiologically. 
Under certain conditions Rhizoctonia forms sclerotia on the host 
(carnation) and also on culture media. On the beet brown mycelia 
but no sclerotia develop. The mycelium is peculiar in its method of 
branching, and in the formation of certain hyphal elements which 
function as spores. The germ tubes of these nearly iso-diametric 
elements often bore through the septa of empty cells to which the 
germinative cells are still attached. The fungus grows well in acid 
media, but is very sensitive to alkaline media, and this suggests 
methods of treatment, że., by liming the soil. The similarity of all 
of the forms studied suggests that some other so-called species may 
likewise prove to be the same organism, and at present the plant 
cannot be referred to a definite species. 
F. C. Stewart: Zhe Stem-Rot Diseases of the Carnation. — Under 
the name “ stem-rot” or “die back” at least two distinct diseases 
have been confused. One is caused by Rhizoctonia ; the other is 
due to a Fusarium and is, perhaps, identical with Sturgis’s carnation 
