Abstract
Cell counts and differential stains indicate that about 90% of cells in viable areas of a homologous myxomatous tumor of hamster check-pouch are probably of one single type. The cytoplasm of these cells contains granules which stain with periodic acid Schiff reaction and are different from granules of mast cells in the same sections. Most of the parenchymal ground substance gives the alcian blue reaction for acid mucopolysaccharides, but some stains with the periodic acid Schiff reaction in the same manner as the cytoplasmic granules.