124 The American Naturalist. — [February,. 
der Kartoffelknollen may be found in Oesterreichisches landwirts- 
chaftliches Centralblatt, Jahrg. I, Heft 1, 1891, pp. 11-26, 2 text 
figures. 3 
The rot of the potato has been known to the agriculturist 
for a long time and was described by Julius Kühn as early as. 
1830. Since that time it has been noticed or written upon ex- 
tensively by many persons, e. g., de Bary, Hallier, Reinke and 
Berthold, van Tieghem, Sorauer. For a time owing chiefly to- 
the writings of de Bary, its ravages were confounded, especially 
in the popular mind, with those due to the potato mildew, Phy- 
tophthora infestans, but it has no necessary connection with this 
fungus although in Europe, at least, it usually follows the ` 
latter. Prior to Dr. Kramer’s investigation the organism as- 
sociated with the rot was usually considered to be Bacillus 
amylobacter van Tiegh. and this was supposed to be the same 
as the Vibrion butyrique of Pasteur, Bacterium navicula Reinke 
and Berthold, Amylobacter clostridium Trécul, Bacillus butyricus 
de Bary and Clostridium butyricum Prazm., but no one had ap- 
proached the problem from a purely bacteriological standpoint 
using approved methods of isolation and inoculation. 
The object of the author in undertaking this series of experi- 
ments was to determine first of all whether the wet rot was 
actually due to bacteria and, if so, how they gained entrance 
into the tuber; second, to identify the species and determine 
its morphological and biological peculiarities; third, to deter- 
mine what decompositions it was capable of producing in the 
potato and in other substrata. Owing, says Dr. Kramer, to the 
fact that several bacteria cause the butyric fermentation and 
several color blue with iodine and agree in morphological par- 
ticulars more or less closely with Clostridium butyricum Prazm- 
(Bacillus butyricus de Bary) “ it appears still very questionable 
whether the specific cause of the wet rot is C. butyricum Prazm., 
especially as the predicated cause was not studied critically in 
relation to its morphology and biology by the above named 
investigators [Reinke and Berthold, yan Tieghem, Sorauer].” 
(2) Geographical Distribution—Potato rot occurs in many 
parts of the world, in fact almost wherever the potato is cultiv- 
