138 The American Naturalist. [February, 
in considerable numbers. Dr. Sorauer attributed the infection 
of sound tubers to this cause and Dr. Kramer was thus able to 
confirm it. 
(3) Conditions Favoring the Spread of the Disease-—There is 
nothing on this subject beyond the statement that potatoes rich 
in sugar would be attacked and destroyed sooner than those 
rich in starch. It is clear, however, that this disease is likely 
to be most prevalent in warm and wet autumns, high tempera- 
tures and excessive rainfall offering favorable conditions for 
its development. 
(4) Methods of Prevention—No experiments, and no observa- 
tions. Disease not studied in the field. Of course, whenever 
warm, rainy weather occurs in autumn potato rot of some sort 
is likely to appear, and common sense would dictate the prompt 
digging of the tubers and their storage in thin layers in a 
dry place, otherwise the whole crop may be destroyed in the 
ground, or subsequently in the pit or cellar. 
Remark.—In the later stages of decay Bacillus fluorescens is 
quite common, and one is also likely to find almost any of the 
common soil bacteria. This paper was announced only as a 
preliminary communication, but no second paper has been 
published, so far as known to the writer. 
This organism differs from Bacillus amylobacter van Tiegh. 
(Clostridium butyricum Prazm.) in that the latter is strictly 
anaerobic, produces spores in spindle shaped cells and colors 
blue with iodine. Bacillus butyricus Botkin, which is thought 
by Lehmann and Neumann (41) Bakteriologische Diagnostik, 
Munich, 1896; Bd., II, p. 315, to be distinct from the preceed- 
ing, is also strictly anaerobic. Bacillus butyricus Hueppe differs 
from Dr. Kramer’s organism in the way metioned above (II) 3 
(5) in the absence of gas production, and in some less impor- 
tant particulars. A number of other butyric acid forming 
species have been described but all more or less imperfectly. 
