The Demonstration of a "Host-Factor" in Commensal Crabs

union. For his survey, Davenport turned to the almost infinite possibilities for such study which exist in the marine fauna. In this paper the author is reporting the results of investigations concerning the commensal relationships of four marine decapod Crustacea occurring in large populations in the Beaufort, N. C., area. The problem was to ascertain if these crabs, commensal with members of three other phyla, exhibited any evidence of a chemical basis for the establishment or maintenance of the commensal union.