Pulmonary lesions produced by fibroma viruses in squirrels and rabbits.

rabbit fibroma in gray squirrels (Sciurus carolinensis). The methods of preparation and passage of the squirrel fibroma virus and the performance of neutralization tests were described (17). Subsequently, passage of the virus in suckling squirrels was accomplished, and some unusual pulmonary lesions were found in one of the suck ling squirrels 50 days after inoculation (15). Gross ly, the lungs contained many "pearl-like" lesions 3-4 mm. in diameter. Histologically, these lesions were epithelial rather than fibromatous and re sembled pulmonary adenomatosis as seen in man and some other animal species. We have recently had the opportunity to ex amine the lungs of two other suckling squirrels inoculated with the squirrel fibroma virus, and the adenomatosis-like lesions were again found. This report describes the histopathology of these lesions and presents some additional experimental observations on pulmonary lesions produced by fibroma viruses in squirrels and rabbits.