hallucinogen. Their neighbors, the Inganos, add the amaran- 
thaceous Alternanthera Lehmannii. The Kofan and Jivaro 
tribes value the solanaceous Brunfelsia as an admixture. 
Makuna medicine men in the Colombian Vaupes add a few 
crushed leaves of the apocynaceous Malouetia Tamaquarina 
A.DC. Tobacco is occasionally used as an admixture 
(Schultes, 1957). Several lianas, without identification, are said 
to be added, but it has not been possible to identify them for 
lack of specimens. A very thorough field and laboratory study 
of plant additives to ayahuasca by the Swiss biochemist Lau- 
rent Rivier and the Swedish chemist Jan-Erik Lindgren has 
disclosed the use of at least two dozen plants, including ferns 
and several cactuses (Rivier and Lindgren, 1972). 
Recently, two of the many admixtures have attracted special 
attention, because phytochemical investigation of botanically 
vouchered material has substantiated folk uses. More often 
than not, specialists have explained away indigenous uses of 
plants as being grounded in superstition. These two admixtures 
in question are Banisteriopsis Rusbyvana (Ndz.) Morton and 
Psychotria viridis R. et P. The leaves — not the bark — of both 
plants are used, apparently never together, however, as admix- 
tures. 
In 1965, the French chemist M. J. Poisson reported that the 
leaves of Banisteriopsis Rusbyana contained relatively high 
concentrations of N,N-dimethyltryptamine (Poisson, 1965). 
This discovery, corroborated by several later investigators 
(Agurell, Holmstedt and Lindgren, 1968; der Marderosian et 
al., 1968) was the first report of a tryptamine in the Malpighia- 
ceae. There were also minor tryptamines present, as well as 
traces of B-carbolines. The leaves of B. Rusbyana, known in 
Colombia and Ecuador as oco-yajé, are said to heighten and 
lengthen the visual hallucinations of the intoxication. It is now 
clear that there is a chemical basis for this use: the resulting 
drink, containing the 6-carboline alkaloids of B. Caapi and B. 
Rusbyana — both hallucinogenic indole derivitives — 1s, in 
effect, far more potent. 
More recent field work has indicated the use as additives in 
widely separated parts of the Amazon of the leaves of several 
species of Psychotria — especially P. viridis (der Marderosian, 
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