This book approaches the question of serologic tests from an unusual and interesting point of view. Positive reactions between blood serum and lipid antigens are shown to occur in normal persons, and only under carefully regulated conditions do they become diagnostic of syphilis.
The first and last sections of the book are devoted to a discussion of the "universal serologic reaction." The procedure to which this term is applied was devised by Kahn and consists of a series of quantitative Kahn tests set up in 10 different concentrations of sodium chloride solution, from 0 to 2.1 per cent, and with serum dilutions ranging from 1 to 640. The results are read immediately and after four and 24 hours of ice box incubation.
In the lower and higher salt concentrations, some flocculation always occurs, particularly at the four and 24 hour readings. The standard quantitative Kahn test with 0.9 per cent