The toxicity of 2 new spp. of Lathyrus (L. splendens and L. strictus) for white rats has shown that L. splendens is of about the same toxicity as L. latifolius (previously studied) and 25% as toxic as L. sylvestris W. The toxicity of the latter sp. was also studied in the guinea pig, rat, rabbit and white rat. By the use of exchange resins and a 30% E + OH extract, it has been possible to concentrate the toxic principle of L. sylvestris about 40-fold.