The cause of the peculiar disease known as sickle-cell anemia is unknown. Clinical reports have been given by a number of authors (Herrick,1Huck,2Graham,3Mulherin and Houseal,4Sydenstricker,5Anderson,6Archibald,7Browne,8Cooley and Lee,9Dreyfoos,10Hamilton,11Alden,12Josephs,13Steinfield and Klauder,14Milliken,15Smith,16Wollstein and Kreidel,17Dolgopol and Stitt,18Fradkin,19Scriver and Waugh20). The disease is limited almost exclusively to the Negro race and is familial and hereditary. There is a possibility that it may rarely occur in the Caucasian race (Castana,21Stewart,22Lawrence23). It is estimated that about 7 per cent of Negroes have the sickle-cell trait; i. e., after anaerobic incubation the "sickling" of the erythrocytes occurs (Miyamoto and Korb,24Graham,3Cooley and Lee,9Brandau25). Relatively few of these persons