By the nineteenth century, the transfer of exotic plants and the search for wild plants that might be domesticated were activities that were becoming rationalized and organized and put at the service of industrial capitalism. Collectors were sent from Europe to the farthest reaches of the earth in search of unknown species that might serve as raw material, remedy, or ornament . This enterprise, even though it was the expression of scientific and state bureaucracies, nevertheless partook of romance: It was a quest for the rare, the precious, and the danger-scented. .
Of all the great feats of that era of botanical discovery, none was more imposing than that of the domestication of rubber. New World inhabitants had shown rubber, which they obtained from several tropical plant species, to early explorers, including Columbus. Since it was an unstable product, it remained for more that three centuries a mere curiosity. Then, in 1839, it was founded that through treatment with sulphur and heat, rubber's elastic properties could be made more permanent . Its applications multiplied and the exploitation of many wild rubber-bearing plants, including some that were soon discovered in Asia and Africa, was much intensified. .
When the world was ready for rubber, the Amazon Region began the spectacular period of forest exploitation which resulted in scattered settlement in widely separated places. In the tropical rain forest south of the main stream, and in the headwater areas of eastern Bolivia, Peru, Ecuador, and Colombia, there are two chief species of tree which rubber can be produced. The better of these species is Hevea brasiliensis, from which latex, a milklike substance, can be extracted from cuts in the bark. The other is the Castilla ulei, from which rubber can be extracted only by cutting down the tree . Like all the other species in the tropical rainforest, both Hevea and Castilla trees are widely scattered, seldom with many individual standing close together.