Abstract
Since the early work of Nuttall (1888), Buchner (1889), and others first disclosed the bactericidal property of normal serum, a considerable amount of attention has been devoted to this important biological phenomenon. The literature (which has been reviewed recently by Knorr, 1929) lacks, however, a comprehensive and co-ordinated study of the subject, and in fact presents a good many confusing data in regard to the nature of the active principles concerned and their immunological significance.