1. Rabbits in which a mild grade of glomerular damage has been produced by small doses of diphtheria toxin develop a severe glomerulonephritis corresponding to the extracapillary form described by Volhard and Fahr after inoculations with sublethal quantities of Bacillus coli.
2. Similar, though not completely identical lesions are produced when diphtheria toxin is followed by intravenous injections of Vaughan's split protein (poisonous part) of Bacillus coli.
3. The inference is drawn that under the experimental conditions described Bacillus coli undergoes bacteriolysis and produces glomerular lesions through the toxic groups contained within its protein molecule.