On a pleuropneumonia-like organism in lung lesions of rats, with notes on the clinical and pathological features of the underlying condition

A pleuropneumonia-like organism resemblingL1in all characteristic features has been isolated from a well-known lung condition of rats of hitherto obscure etiology in seventeen out of nineteen cases. 2. Morphological elements which presumably initiate growth in culture have been demonstrated microscopically in the lesions. 3.Streptobacillus moniliformis(i.e.L1plusStreptobacillus) is a frequent inhabitant of the nasopharynx of rats with lung lesions; it may secondarily invade the lungs as it is found in severe cases together with theL1organism. 4. An account is presented of the clinical and pathological features of the underlying condition with which the newly discovered bacteriological findings are associated. 5. The precise role played by theL1organism in the pathogenesis of the lung lesions in rats has still to be established and further experiments with this end in view are in progress.