A Quantitative Precipitation Test for Syphilis.

in February, 1946, under the title of "A Preliminary Report on a Modification of the Kahn Test" (Price, 1946a), the author described a modification of the Kahn test, the advantages of which were stated to be: (1) that the results are more easily read than those of the Kahn test; (2) the results given by antigens prepared at different times and having different titres are identical; (3) the results obtained by this test appear to be somewhat more specific than those given by either the Kahn or Wassermann reactions. After more than 3,000 tests there seems to be no reason to modify these opinions. One major disadvantage remained, that is, the difficulty in the preparation of the alcoholic extract of dried heart muscle according to Kahn's technique. If, moreover, one considers the production of the dried heart powder itself, the manufacture of Kahn antigen is outside the scope of most pathological laboratories. It is, therefore, desirable from all points of view to attempt to prepare an antigen which can be made in any laboratory, is specific in action, reasonably sensitive, and easy to handle.