From the experiments detailed in this paper it may be concluded that Amanita phalloides contains besides phallin, or the hæmolytic principle of Kobert, another body of toxic nature. Phallin is thermolabile, and is destroyed by the action of pepsin and pancreatin. The other toxic body is thermostable and is resistant to pepsin and pancreatin. The two substances, moreover, possess different toxophoric and haptophoric groups, since an antiserum produced by the immunization of animals to the thermostable body has no neutralizing effects upon phallin. The thermolable body, phallin, produces the subcutaneous œdema and hæmoglobinuria, and, in virtue of its blood-laking properties, the pigmentation of the spleen. The thermostable body produces hæmorrhage and necrosis, and the fatty degeneration of the parenchymatous organs. The two bodies exist side by side in watery extracts of the fungus, but they cannot be considered as two constituents of a single poison exerting a variety of effects. To the hæmolysin the name phallin has already been given by its discoverer, Kobert. For the thermostable substance described now for the first time, the name Amanito-toxin is proposed provisionally.