“…The findings agreed with those of other workers in obtaining a high percentage of positive intradermal tests among negroes, in the frequency of positive intradermal tests for both chancroid and lymphogranuloma venereum in the same patients, and in the high rate of positive findings among syphilitic patients. Heisel and Stroud (1943) found that the yolk sac antigen provided a fairly reliable test for the disease, but that positive reactions did not always indicate the presence of disease. They thought that a papule 7 mm.…”