These obviously have great practical importance, and 
the world-wide utilization of the active principle is out- 
standingly beneficial to man. Nevertheless, I must point 
out that the chemical studies of these narcotics and stim- 
ulants are far from complete. This is due primarily to 
the poor quality of properly identified materials on which 
previous investigations have been based. Furthermore, 
medical and therapeutic studies have usually been made 
on animals and in surroundings completely different from 
the natural environment. 
The experiences realized personally by some of the 
naturalists and ethnographers in the use of these plants, 
so to speak in situ, have relative value, and, together 
with detailed descriptions by travellers or trustworthy 
natives, they give us some idea of the actual effect of 
these plants on man. Without in any way detracting 
from these investigators, we must say that in their ac- 
counts of the uses, kinds, collection, preparation, cere- 
mony, symbolism and mythology of narcotic and stim- 
ulant plants most writers offer very incomplete data and 
usually fail to preserve material on which definite botan- 
ical determinations may be made. Furthermore, in the 
‘ase of those naturalists of the past century who wrote 
down careful notes on the uses of plants and gathered 
specimens which permitted proper identification, the 
name of the tribe involved was often not critically de- 
termined. 
My own experiences with some of the tribes of Co- 
lombia, my personal contacts with other investigators 
with field experience and my recent study of the litera- 
ture have made it possible for me to clarify and amplify 
many points which hitherto have been poorly understood. 
My former purely ethnological approach has, during the 
past year, been enriched by a botanical panorama, espe- 
cially in the field of narcotics and stimulants, made pos- 
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