The circumvallate papillae and foliate papillae of the pigs tongue were studied with an optical and an electron microscope. The materials was obtained from 15 individuals (original country ; Hampshire and Landrace) ages 6-7 months. Main results obtained were as follows. 1. The circumvallate papillae, showing ellipse in shape, were found in a pair symmetrically located near the indistinct border between the tongue root and body. The secondary papillae, which were well developed were observed over 10 in number on their dorsal surface. There were the mucous glands, opening to their dorsal epithelium surface, and solitary lymphonodules in the lamina propria mucosae. 2. The foliate papillae, showing oval bulges on the mucous membrane, were found in a pair symmetrically located on the tongue margin opposed to the circumvallate papillae. They consisted of parallel ridges with 3-6 grooves. There were the mixed glands, opening to the bottom of the furrows, and solitary lymphonodules in the lamina propria mucosae. 3. Occassionally, a cell-like structure which filled the taste canal was found in the buds. Its appearance was suggestive of either wandering of a leucocyte or discharge of a cell of the buds. 4. There occassionally occurred buds with two pores among the large-sized ones. 5. Three cell types, I, II and III, except undifferentiated cells in the basal portion were clearly discriminated in the buds, as in other mammalia. 6. There were sometimes recognized the dark cored nuclear bodies in the nucleus of the type II cell, and isolate cilium in the lateral surface of the type III cell. 7. Some of the taste hairs, microvilli, appeared to be had club-like with bulged tip.
