Cambridge, MA: Botanical Musuem of Harvard University, 1963. First edition - Also includes an article on "The Active Principles of the Seeds of Rivea Corymbosa and Ipomocea Violecea." Both papers were written in honor of Robert J. Weitlaner on his 80th birthday. Wasson's paper focuses on the history and the ethnobotanical aspects of the "four great divinatory plants of Mexico at the time of the Conquest" - picietl, peyotl, teonanacatl and ololiuhqui - with the emphasis on the last as the least known to the outside world. Illustrated with plates 28-34, botanical drawing, map. Notes pp 161-193. Hofmann writes on the chemical investigation that led to the isolation of the active principles in this plant, as well as a very brief history of the discovery of LSD. p 194-212 with plates 35-36, references. WorldCat only identifies one holding, although there is a notation about a duplicate copy as part of the Julio Mario Santo Domingo Collection.