When we arrived in Esmeralda, most of the Indians were returning from an excursion they had made beyond the Padamo river to pick juvias, the fruit of the bertholletia, and a liana that gives curare. Their return was celebrated with a feast called in this mission the fiesta de las juvias, which resembles our harvest festivals. Women had prepared plenty of alcohol and for two days you met only drunk Indians. Among people who attach importance to palm-tree fruits and other useful trees, the period when these are harvested is marked by public celebrations. We were lucky to find an Indian slightly less drunk than others, who was making curare with the recently picked plants. He was the chemist of the locality. Around him we saw large clay boilers used to cook the vegetable juices, as well as shallow vessels used for evaporation, and banana leaves rolled into filters to separate the liquid from the fibers. The Indian who was to teach us was known in the mission as master of the poison, amo del curare; he had that same formal and pedantic air that chemists were formerly accused of in Europe. 'I know, he said, 'that whites have the secret of making soap, and that black powder which scares away the animals you hunt when you miss. But the curare that we prepare from father to son is superior to all that you know over there. It is the sap of a plant that "kills silently", without the victim knowing where it comes from.