Certain differences between the native and experimental administration of hallucinogens, such as another route of adminsitration, should not be disregarded. To set an example, the ritual use of Anadenanthera enemas by South American Indians is discussed. In pharmacological studies Anadenanthera alkaloids have been found to produce the alleged effects of these dosage forms. However, in contrast with dimethyltryptamine and its 5-methoxy derivatives, bufotenine is likely to have no or only a eak central activity. Up to now oral administration has not been demonstrated to be effective, although relatively larges doses have been studied. As first-pass metabolism is a likely cause of this inactivity, it cannot be safely assumed that rectal administration will give better results than oral administration.