1. Licensed (U. S.) Schick-products of different manufacturers give inconsistent results.

  2. Of the 87 individuals Schick-tested each with 6 different products, 30 (34 per cent) showed inconsistencies and 23 (26 per cent) showed frank disagreement in the readings.

  3. Reactions to the toxins of the Schick-outfits were remarkably constistent with the exception of one product.

  4. Errors in interpreting the “Schick-immunity” were usually due to the inconsistent reactions ensuing upon the Schick-control.

  5. False interpretations of the Schick-test are most frequently made in the group of persons skin sensitive to diphtheria-protein.

  6. Products containing dilute toxoid as a Schick-control were the only ones which resulted in no errors of interpretation of the “Schick-immunity” of the persons tested. All products using heated toxin as a control gave some false results.

  7. Our findings substantiate the fact that the antitoxin-level of “Schick-immunity” lies between 1/500 and 1/250 of a unit of antitoxin, when the Schick-test-material conforms to the standard recommended by the League of Nations.

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