All of the Rhus plants found in Japan contain albumen crystals in latex. Such crystals are relatively abundant in latex oozed from such soft tissues as leaves and very young sterns of . sprouts, while in roots, flowers, fruits and seedlings, a few in number- and kind. In lalex from old roots or stems, almost no crystals at all can be found. In latex from Rhus succedanea, Rh. silvestris and Rh. vernicifera, we find crystals? spear, rectangular, . or cone shaped, but only rectanglar ones in latex of Rh. Toxicodendron var. vulgaris; and large polygonal crystals in Rh. semialata var. Osbeckii. Although almost all the crystals in latex from Rh. trichocarpa resemble in shape those of Rh. succedanea, Rh. silvestris and Rh. vernicifera, we find, in addition, rarely small polygonal crstals. The latex of Rh. succedanea, Rh. silvestris, Rh. vernicifera , Rh. Toxicodendron var. vulgaris and Rh. trichocarpa is poisonous, and contains numerous smaller crystals, while a few extremely large crystals are observed in the nonpoisonous latex of Rh. semialata var. Osbeckii. As pointed out above, the kind, num b er and size of the crystals vary with the different species of the Rhus plants. They are related to the morphological characters of the Rhus plants being linked with especial intimacy to those of the fruits, and, moreover, to the chemical property of the latex.