THE ESTABLISHMENT OF AN ALBINO RAT COLONY FREE FROM MIDDLE EAR DISEASE.
A special colony of albino rats was built up by selection and isolation from a population in which middle ear disease was highly prevalent. No cases of aural infection occurred in the selected group, whereas its precursor showed a crude incidence of 57 per cent. The subjection of selected rats to a rachitic diet and to overcrowding did not predispose to the development of middle ear disease. The incidence of pneumonia was not similarly affected; thus, 52 per cent of the adult selected rats showed pulmonary lesions, and 78 per cent of the adult stock rats. There was, however, a significant reduction in the number of cases which showed advanced pulmonary lesions. Certain theoretical considerations of middle ear disease and of pneumonia are discussed.
Department of Animal Pathology of The Rockefeller Institute for Medical Research, Princeton, N. J.
J B
JB
Nelson
J W
JW
Gowen