Letter to Edmond Souchon from William Osler, From the Regius Professor of Medicine, Oxford, Oxfordshire, England. Refers him to Garrison and recommends his book on the History of Medicine. The only contributions of his that are worth mentioning are 1-the determination of the blood platelets as separate elements in the circulation. 2-the work made with Thayer, MacCallum and Lazear, in connection with malarial parasites 3- the work helping to place amoebic dysentery on a pathological and clinical foundation 4- the full clinical description of the polycythemia rubra, or erythremia 5- the description of hereditary telangiectasis with epistaxis 6- the clinical descriptions of the visceral types of purpura and angio-neurotic-oedema. Compliments on his aneurysm paper.