1897.] The Bacterial Diseases of Plants : 135 
(b) Formation of Acids. —The bacillus produces a strong acid 
reaction in solutions or substrata containing sugar, i. e., in the 
potato; in steamed potato juice with addition of 1-2 per cent 
dextrose; and in dextrose solutions containing tartrate of 
ammonia and the necessary mineral substances; but not in 
starch paste with ammonium tartrate and the nutrient mineral 
substances, nor in peptone solutions containing nutrient 
mineral substances. This acid was determined to be butyric 
and in the following manner. The soft contents of a tuber in 
the first stage of rot while still acid, was extracted in water by 
boiling, filtered, and mixed with a small quantity of calcium 
carbonate. A white precipitate resulted, presumably of calcium 
butyrate. This was, consequently, filtered boiling hot. The 
precipitate which crystalized out of the liquid exhibited under 
the microscope the very characteristic rhombic prisms of 
calcium butyrate. When this salt was mixed with dilute 
hydrochloric acid a fluid resulted which was miscible in water, 
had a boiling point of 163° C., and possessed the characteristic 
smell of butyric acid. 
(c) Production of Alkalti—In the second stage of the rot the 
tissues show a strong alkaline reaction. Ifa little of the soft 
contents of a tuber in this stage of the rot is mixed with a few 
drops of distilled water, the fluid filtered, and the filtrate mixed 
with Nessler’s reagent, a decided brown color appears instantly, 
indicating ammonia. A part of this ammonia combines with 
the free butyric acid to form ammonium butyrate and the 
remainder serves to render the decomposed tissues strongly 
alkaline. The ammonia is attributed to the decomposition of 
albuminoid substances by the bacillus. As additional evi- 
dence, it is stated that if a 5 per cent peptone solution contain- 
ing the necessary nutrient mineral substances be inoculated 
with a pure culture of this bacillus, a sort of rotting fermenta- 
‘tion takes place, the first evidence of which is a strong am- 
moniacal smell. Nessler’s solution indicates the presence of 
ammonia. ; 
(d) Formation of Pigment.—Growth described as dirty-white 
on agar, gelatin, and cooked potato. 
