in as temperate and unbiased a manner as possible, but to write about lynching without discussing religion and sex among its causes is to leave the root of the matter unexplained.
To many who have been of great help to me I wish here to make grateful acknowledgment. These, among many others, include James Weldon Johnson, Arthur B. Spingarn, and Charles S. Johnson for critical reading of the entire manuscript; Dr. Raymond Pearl, of Johns Hopkins University, for much valuable aid and for reading the chapter on "Science, Nordicism, and Lynching"; Sir Arthur Keith, president of the British Association for the Advancement of Science, for many useful suggestions in the gathering and use of material in the same chapter; Miss Beatrice Blackwood, of the Department of Human Anatomy of Oxford University, who so patiently aided in the search for authoritative opinion upon certain questions of the relation between ability and brain-structure, brain-weight, and head-form; Dr. W. E. B. DuBois, editor of the Crisis, and Dr. Melville J. Herskovits, of Northwestern University, for advice, information, and guidance; Professor Robert
