The discovery of the principle of complement deviation, and its application to syphilis by Wassermann, introduced a new era in medicine. Deviation for diseases other than syphilis have been elaborated with varying success, and attempts have been made by some to simplify and by others to render more delicate the original method suggested by the discoverer of the reaction. The significance of the entire test was for a time under discussion, but thanks to laboratory workers the importance of the Wassermann reaction has received a definite status and has been so well studied that, in conjunction with the analysis of the cerebrospinal fluid, it occupies a position second tonone in the neurologic laboratory to-day. A series of tests have been introduced for rendering assistance especially in neurologic cases, and it seems that the endeavors along this line are by no means exhausted. Most of these experiments have utilized the cerebrospinal