Racial and Environmental Factors in Susceptibility to Rhus

For reasons that are obscure at this time, certain dermatoses have racial or geographic peculiarities of distribution. The Negro is considered to be comparatively immune to basal-cell epitheliomas but particularly susceptible to the annular syphilid. Howard Fox, 1 after a study of 2200 Negroes and an equal number of whites, reached the conclusion that the Negro is less susceptible to external contacts. To quote his article of 1908: An example of lessened susceptibility to vegetable irritants is given by my statistics for poison by the Rhus toxicodendron, which showed 22 cases in the white against 8 in the black. While these figures show a much greater prevalence of ivy poisoning in the white, the disproportion in my opinion would have been much greater in a comparison of whites with full-blooded Negroes. In replying to the question, Is the Negro immune to ivy poisoning? the answer, I have