Comparative cytochemical studies by micro‐incineration of a saprozoic and an holozoic infusorian

Nyctotherus cordiformis and Opalinids infesting Rana pipiens were studied by microincineration and in stained control sections. A marked difference in concentration and distribution of mineral salts was noted within saprozoic and holozoic organisms. The endoplasm in the saprozoic protozoa was free from inorganic residue except for the ‘vegetative’ granules; the protoplasm of the holozoic infusorians consisted of a fine network of mineral salts. Detailed examinations suggested that the qualitative and quantitative differences might be correlated with diffusion of digestible material through the cuticle. The inorganic residue of the walls of vacuoles was relatively rich in iron.