1897 | ABSTRACTS OF BOTANICAL PAPERS 193 
Bacillus solanacearum.—The dark brown pigment produced by 
the potato rot bacillus will not dialyze, or does so only very 
imperfectly, and is precipitated by compounds of calcium and 
of iron. It was suggested as a working hypothesis that the 
humus compounds of the soil are due solely to the chemical 
action of fungi and bacteria on the carbohydrate materials of 
animals and plants, especially the latter. 
