In 1938 Troland and Lee1 reported 3 cases of thrombopenic purpura in which they were able to prepare from the patient's spleen an extract which had platelet-reducing properties when injected into rabbits. In all 3 cases splenectomy resulted in amelioration of symptoms. The spleens were small, the largest weighing 136 Gm. Similar work had been reported by Torrioli and his associates,2 beginning in 1933; attempts at confirmation have thus far been inconclusive.3 Following the methods of Troland and Lee, we attempted to confirm their results. Our first extract was prepared from a spleen removed at another institution. We were able to secure three more spleens, one from the surgical service of the Flower and Fifth Avenue hospitals.
—Splenic tissue was chopped fine and placed in five times its volume of reagent acetone (chemically pure) immediately after removal. The first extract (to be known as extract