Syphilis manifests itself in the human organism by a multiplicity of lesions in the skin, mucous membranes, glands, blood vessels, bones and viscera. Besides its physical manifestations, syphilitic infection produces an alteration in the blood serum. Reasoning from the analogy furnished by other infections, with the immunology of which we are better acquainted, one may assume that the alteration in the blood serum of the syphilitic patient is multiple, and due to the elaboration of certain products by the action of Spirochaeta pallida on the tissues of the human host. We are as yet unfamiliar with the exact nature of the products of syphilitic infection. A syphilotoxin probably exists, but immunology has not furnished any exact proof of this.
Since the advent of the Wassermann test we have possessed a method for the detection of a certain property commonly present in the serum of syphilized persons, namely, the property of