and carcinoma of the colon, and it may not be too far-fetched to suggest a common cause. Megakaryocytes and platelets have been shown to play an important part in viral multiplication in certain forms of cancer in animals (de Harven and Friend, 1960; Gross, 1963), and more recently thrombocytosis has been reported in human cancer (Levin and Conley, 1964). My own observations are in agreement wi...