This article presents experimental evidence that positive reactions of nonspecific nature encountered in the serodiagnosis of syphilis can be identified by means of a practical laboratory procedure. Non-specific serologic reactions are relatively widespread biologically. They are a common finding in lower animals; they are met with in diseases other than syphilis and are given in isolated instances by normal persons. The occurrence of these reactions in the absence of syphilis in human beings has tended to weaken the entire structure of the serology of this disease; it has rendered the diagnosis uncertain in many asymptomatic cases, and it has lowered the confidence of physicians in serologic reports. This situation has served as a stimulus to direct efforts toward the development of a method which would aid in detecting these reactions. The problem is not yet solved, but a beginning has been made toward its solution. EXPERIMENTAL APPROACH In attempting to