In a study of this scope one necessarily incurs considerable debts to colleagues for aid generously given and gratefully received. The notes of James Mooney on Kiowa, Comanche, and Tarahumari peyote, deposited in the Bureau of American Ethnology, as well as manuscripts by Frances Densmore on Winnebago, and Dr. Truman Michelson on Sauk and Fox peyote, were made available through the generosity of Dr. Matthew Stirling, to whom I express particular thanks. Mrs. Elna Smith very kindly lent further Bureau of American Ethnology material which had been in her care. Mr. D. F. Murphy of the Indian Office amplified my Osage notes, and Mr. John Collier, Commissioner of Indian Affairs, has been generous with information of legal and administrative nature. To Donald Collier, student at the University of Chicago, and Ing. Luis Híjar y Haro of Mexico City, I express appreciation for bibliographic items, as well as to Dr. Ralph Beals of the University of California at Los Angeles. Richard Schultes, student at Harvard University, who was with me for an ethnobotanical study during several weeks of my second summer of work, has also been generous in giving help on bibliographic as well as botanical and pharmaceutical matters. Dr. E. A. Hoebel of New York University made available his notes on Northern Cheyenne and Comanche peyote. Dr. Ruth Benedict of Columbia University and Dr. M. E. Opler of the University of Chicago have aided with Mescalero Apache notes, and the latter has very generously lent valuable manuscript notes on Tonkawa, Carrizo and Lipan peyotism. Dr. Frank Speck of the University of Pennsylvania was fertile with suggestions during the second period of field work, and since its completion has contributed important Delaware material. Mrs. Erminie Voegelin, student at Yale University, kindly lent her voluminous notes on Shawnee peyote, as did Mrs. Anne Cooke for the Ute, and John Noon, student at the University of Pennsylvania, for the Kickapoo. Dr. A. H. Gayton kindly lent an interesting paper on datura. While the present paper was still in proof form, Dr. Leslie A. White of the University of Michigan and Dr. Fred Eggan of the University of Chicago generously lent material on Taos and Northern Cheyenne peyotism respectively. To Dr. Edward Sapir of Yale University, to the Laboratory of Anthropology at Santa Fé, and to Dr. Clark Wissler of the American Museum of Natural History, I wish to express my thanks for making available the funds on which field work was undertaken. To Dr. Sapir and to Dr. John Dollard of the Institute of Human Relations at Yale University I owe the warm personal debt of founding a knowledge and an interest in matters of psychological import herein treated. And to Dr. Leslie Spier, my dissertation adviser, I express gratitude for his constant stimulating interest, valuable bibliographic help, and leads of considerable ethnographic significance. WESTON LA BARRE