For the last twenty-five years, the wide distribution of the endameba throughout the temperate zone has provoked much discussion. One of the most significant reports is that by Kofoid and others,1who examined the stools of 1,500 soldiers. They foundEndameba histolyticapresent in 3 per cent, of the home service men and in 10.8 per cent, of the overseas men. It is unlikely that the incidence of this ameba is greater in Europe, but the impaired sanitary conditions of actual warfare permitted the 3 per cent, to increase to 10.8 per cent. I have reviewed the last five years' work in the Mayo Clinic, from 1920 to 1924, inclusive. In this period the endameba was identified in 533 cases; however, less than 5 per cent. of all patients are subjected to stool tests. INCIDENCE AND GENERAL CONSIDERATIONS OF THE ENDAMEBA As may be seen by the map, most