a test for susceptibility to Corynebacterium diphtheriae toxin: 0.1 mL of Schick test toxin is injected into the skin of one forearm (test site) and the same quantity of the same, but heat-inactivated, material into the skin of the other forearm (control site); those with toxin-neutralizing antibodies either will have no reaction at either injection site (negative test) or may have a pseudoreaction due to antibodies for substances (antigens) in the test materials other than diphtheria toxin; people lacking toxin-neutralizing antibodies may have a positive reaction, which consists of an area of redness appearing 24-36 hours at the test site only and persisting for 4-5 days. SYN: Schick method.