Paullinia Yoco is apparently the first plant in which the 
bark is utilized for its caffeine content. 
IV. Notes on related species of Paullinia 
It is of interest to note that Paullinia and the very 
closely related genus Serjania contain extremely toxic 
species, including a number of very active fish-poisons. 
Paullinia Cururu 1. is an ingredient of a certain type 
of curare in South America. Paullinia australis St. Hil. 
is a highly toxic Argentinian species containing in its 
leaves and roots a sedative and narcotic alkaloid. The 
bark of the roots of Paullinia pinnata L.. (timbo) is a nar- 
cotic poison, and in Brazil certain Indians are said to em- 
ploy it in the preparation of a slow poison. 
Guarana, derived from Paullinia Cupana HBK., said 
to be the most stimulating of all the caffeine beverages, 
is used in most of the Amazon Valley of Brazil as a coffee 
substitute. The seeds are pulverized, mixed with cassava 
flour (Manthot esculenta Crantz), and formed into small 
moulds of various shapes. Upon drying, these moulds 
become very hard. The beverage, which is made by dis- 
solving this pasta guarand (‘‘guarand paste’’) in hot or 
cold water, is astringent and bitter due to the rather high 
tannin content (2-8%) of this species. The stimulant 
properties are due to the high caffeine content which is 
usually 8-4%, but which may occasionally be as high as 
6%. Paullinia sorbilis Mart., usually considered to be the 
same as P. Cupana, but which is possibly distinct, is also 
a source of guarana. 
V’. The use of yoco 
The area in which yoco is employed as a stimulant is 
rather restricted, comprising, according to all available 
reports, the Comisaria del Putumayo and the western- 
most part of the Comisaria del Caqueta in Colombia, a 
[ 314 ] 
