This report presents the histopathologic findings in serially sectioned biopsy specimens taken from the scalps of experimental subjects inoculated with Microsporum audouini and Microsporum canis. The principles governing the pathogenesis of this type of scalp ringworm have been presented in a previous communication.1 Forty-one scalp specimens from adults and children subjected to biopsy at various times after inoculation comprise the experimental material. Sixteen specimens were from M. canis cases and the remainder were from cases of M. audouini. Alternate sections were stained with hematoxylin and eosin and the Hotchkiss-McManus stain. In addition, 11 biopsy specimens from persons naturally infected with M. audouini and 3 from M. canis infections were studied. Kerions and other inflammatory scalp reactions are not herein considered. These latter are specialized variants of the basic disease indicative of a marked reactivity of the host.
Among the early