I have no doubt that from remotest times the whole valley was filled with water. Everywhere the shape of the promontories and their steep slopes reveals the ancient shore of this alpine lake. We find vast tracts of land, formerly flooded, now cultivated with banana, sugar cane and cotton. Wherever a hut is built on the lake shore you can see how year by year the water recedes. As the water decreases, you can see how islands begin to join the land while others form promontories or become hills. We visited two islands still completely surrounded by water and found, under the scrub, on small flats between 4 and 8 toises above the water-level, fine sand mixed with helicites deposited by waves. On all these islands you will discover clear traces of the gradual lowering of the water.

The chemical operation, whose importance is exaggerated by the master of the curare, seemed to us very simple. The bejuco used to make the poison in Esmeralda has the same name as in the Javita jungles. It is the bejuco de mavacure, which is found in abundance east of the mission on the left bank of the Orinoco. Although the bundles of bejuco that we found in the Indian's hut were stripped of leaves, there was no doubt that they came from the same plant of the Strychnos genus that we examined in the Pimichin jungles. They use either fresh mavacure or mavacure that has been dried for several weeks. The sap of a recently cut liana is not considered as poisonous; perhaps it only really works when it is very concentrated. The bark and part of the sapwood contain this terrible poison. With a knife they grate some mavacure branches; the bark is crushed and reduced to thin filaments with a stone like those used to make cassava flour. The poisonous sap is yellow, so all this matter takes on that color. It is thrown into a funnel some 9 inches high and 4 inches wide. Of all the instruments in the Indian's laboratory, this funnel is the one he was most proud of. He several times asked if por alla (over there, in Europe) we had seen anything comparable to his embudo. It was a banana leaf rolled into a trumpet shape, and placed into another rolled trumpet made of palm leaves; this apparatus was held up by a scaffolding made of palm-leaf stalks. You begin by making a cold infusion, pouring water on the fibrous matter that is the crushed bark of the mavacure. A yellow water filters through the leafy funnel, drop by drop. This filtered water is the poisonous liquid; but it becomes strong only when concentrated through evaporation, like molasses, in wide clay vessels. Every now and then the Indian asked us to taste the liquid. From its bitterness you judge whether the heated liquid has gone far enough. There is nothing dangerous about this as curare only poisons when it comes into contact with blood. The steam rising from the boiler is not noxious, whatever the Orinoco missionaries might say.

Wherever the Temi forms bays the jungle is flooded for more than half a square league. To avoid the bends and shorten our journey the Indians leave the river bed and go south along paths or sendas, that is, canals, some 4 or 5 feet wide. The depth of the water rarely exceeds half a fathom. These sendas are formed in the flooded jungle like paths in dry land. Whenever they could the Indians crossed from one mission to another along the same path in their pirogues. But as the passage is narrow the thick vegetation sometimes leads to surprises. An Indian stands in the bow with his machete, incessantly cutting branches blocking the canal. In the thickest part of the jungle we heard an odd noise. As the Indian cut at some branches a school of toninas - freshwater dolphins - surrounded our boat. The animals had hidden under branches of a ceiba and escaped through the flooded jungle, squirting up water and compressed air, living up to their name of 'blowers'. What a strange sight, inland, 300 to 400 leagues from the Orinoco and Amazon mouths!

Days passed quickly in the Capuchin convent in the Caripe mountains, despite our simple but monotonous life. From sunrise to sunset we toured the forests and mountains near by looking for plants, and have never collected so many. When the heavy rain stopped us travelling far we visited Indian huts and the communal conuco, or attended the nightly meetings when the alcaldes handed out the work for the following day. We did not return to the convent until bells called us for meals in the refectory with the monks. At dawn we sometimes accompanied them to the church to attend doctrina, that is, religious classes for Indians. It was hard explaining dogma to people who hardly knew Spanish. The monks are almost completely ignorant of the Chaima Indian language, and the resemblance of sounds between the languages muddles the poor Indians so that strange ideas arise. One day we witnessed a missionary struggling to explain to his class that invierno, winter, and infierno, hell, were not the same thing, but as different as hot and cold. The Chaima Indians know winter only as the rainy season, and imagine that 'the white's hell' is a place where the evil are exposed to horrific rainstorms. The missionary lost his temper, but it was useless; the first impression caused by the almost identical words persisted; in the Indians' minds the images of rain and hell could not be separated.

The macavahu, called by the missionaries viuditas, or 'widows in mourning', has soft glossy black hair. Its face is a kind of whitish-blue square mask, which contains its eyes, nose and mouth. Its ears have an edge; are small, pretty and hairless. Its neck has a white area in two rings. Its feet, or hind legs, are black like its body, but its forehands are white outside and black inside. These white spots led the missionaries to recognize a veil, a neck scarf and the gloves of a widow in mourning. The character of this little monkey, which sits up on its hind legs to eat, is not related to its appearance. It has a wild and shy air, and often refuses food even when ravenous. We have seen it remain motionless for hours without sleeping, attentive to everything happening around it. The viudita, when alone, becomes furious at the sight of a bird, and climbs and runs with astonishing speed, and, like a eat, leaps on to its prey and eats all it can. The viuditas accompanied us throughout our entire voyage on the Casiquiare and Río Negro. It is an advantage to study animals for several months in the open air, and not indoors where they lose their natural vivacity.

As soon as you enter the basin of the Atabapo river everything changes: the air, the color of the water, the shape of the river-side trees. By day you no longer suffer the torment of mosquitoes; and their long-legged cousins the zancudos become rare at night. Beyond the San Fernando mission these nocturnal insects disappear altogether. The Orinoco waters are turbid, full of earthy matter, and in the coves give off a faint musky smell from the amount of dead crocodiles and other putrefying animals. To drink that water we had to filter it through a linen cloth. The waters of the Atabapo, on the other hand, are pure, taste good, are without smell, and appear brownish in reflected light and yellow under the sun.