3. Acre. This is a far interior territory, bordering on Peru and Bolivia. Acre, which is now federated with Brazil, is very famous for its rubber, which, like that of Amazonas, is generally known as “up-river” rubber. 4. The Brazilian State of Matto Grosso, in the Upper Amazon Valley. At present very little of this vast forest-land between Amazonas and Paraguay has been opened up, but, judging by what has already been seen of its dense jungle, the whole State is a treasure-ground of rubber-trees. Most of the rubber now exported from this district is coarse, and sun-cured instead of smoke-cured. It, too, is called “up-river” rubber. 5 and 6. Bolivia and Peru. Both countries export large quantities of rubber, much of which is of excellent quality. The various grades of Bolivian and Peruvian Para are classed collectively as “up-river” rubber; but the different qualities have native names as well, and these are quite popular as trade terms. The Amazon country furnishes a rubber that is quite distinct from the Para material. It is called “Caucho,” and is obtained from a tree known as the _Castilloa Ulei_. The biggest exporters are Peru and Bolivia. There is no system of estradas to simplify the work of the caucho-gatherers. A search-party, largely composed of Indians, sets out to hunt for castilloa trees in parts of the forest that have never before been explored. There is not so much as a track to help them on their journey, nor a clue of any kind to tell them in which direction to cut their way. In order to collect enough caucho to make a success of their trip they will probably have to travel several hundred miles; quite likely they will lose themselves, and have to wander about for months before they happen to strike the right direction towards some isolated village. All their baggage has to be carried by hand or on the back, so only the barest necessities are taken. A large share of each man’s burden consists of provisions; even so, the stores are scanty enough, seeing that no one knows for how long they will have to be eked out, with the help of any game that may be shot. Every castilloa-tree that is found is felled to the ground, and is then ringed with cuts, which extend the whole length of the trunk, at intervals of about 2 feet. The milk which runs out from these cuts is caught in little bowls. These are either fashioned from leaves, which are folded and sewn together, or they are made from seed-pods--in which case they are called “calabashes”--in the very simple way that you can easily make a cocoanut-shell do duty for a basin or a cup. The contents of the bowls are poured into a hole in the ground or a scooped-out hollow in the trunk of a fallen tree, and the milk is coagulated with the help of soap, lime, or potash. After a few days the lumps of caucho are pressed together into square blocks, the market name for which is “Peruvian Slab.”