Our thanks are also due to Dr. J. F. Waugh of Chicago who has de voted considerable time and energy to the performance of numerous complement fixation tests and to Dr. Hirschfelder of Baltimore for the privilege of embodying the results of his anaphylactic experiments in this report. To Dr. Waldemar Koch of the University of Chicago we owe the first chemical analysis of a pellagrous brain that has yet been published. We' are also indebted to the superintendent of the Cook County Institutions for information concerning pellagra and diet at the Dunning Hospital and to Dr. W. A. Pusey and his assistants at the Cook County Hospital for the privilege of, and assistance in, studying one of the most interesting and important of the cases we have seen. Finally we wish to express our grateful acknowledgements of the zealous and valuable assistance which has been rendered by those who have worked more directly with us. The amount of careful and detailed material has been great and has fallen largely upon their shoulders. Among them should be mentioned especially Mr. A. F. Wussow, Mrs. Josephine (kerr) Allison, Dr. J. T. Books, Dr. Clifford E. Smith and Dr. L. J. Pollock.