1897.] The Bacterial Diseases of Plants : 125 
ated, but by no means all of it is due to the particular organ- 
ism isolated by Dr. Kramer, as the writer of this review has 
proved conclusively (see next review). Considering the read- 
iness with which almost all bacteria grow upon cooked potatoes 
it seems not unlikely that even in its natural state the potato 
tuber may offer a suitable nidus for the growth of a variety of 
bacteria especially when it is kept unduly warm and moist. 
However, this may be, only two bacterial diseases of the potato 
have been worked out conclusively. The distribution of Dr. 
Kramer’s wet rot of the potato is not known. Very likely it 
occurs in North America as well as in Europe but no one has 
established this fact, probably because no one hassearched for 
the organism, his paper having been very generally overlooked. 
Even the European distribution of this rot is a matter of much 
doubt as it has probably been confused with the brown rot due 
to Bacillus solanacearwm. 
The potatoes from which were derived the bacteria used in 
these experiments came from the vicinity of Graz where the 
wet rot was very destructive in the autumn of 1890. 
(3) Symptoms.—Under the influence of this disease the con- 
tents of the tuber becomes soft, pulpy, vile-smelling, and usually 
of a yellowish color. The disease may either attack the tubers 
before they are harvested or during the winter in the store 
houses. If one of these wet rotten tubers is pricked or squeezed 
a fluid pours out which hasa strongly acid reaction and a very 
bad smell, mostly like butyric acid. Gas bubbles are also fre- 
quent. The remaining pulp, which is rather compact, gives 
an alkaline reaction either immediately or after a short time. 
This reaction is plainest in the tissues which have already be- 
come completely pulpy. At the commencement of the de- 
struction of the potato while the tissue is still firm, the reac- 
tion is moderately acid. 
The tubers forwarded to Dr. Kramer for investigation pos- 
sessed all the above mentioned characteristics of wet rot. They 
still had a plump look. The skin was apparently uninjured 
but the whole potato was a bloated sack with a yellow ichor- 
ous contents. When punctured a very bad smelling, sour 
fluid escaped. The smell recalled butyric acid and amin bases 
