The fine rubber tree belongs to the Hevea brasiliensis, Mull. Arg. or to their near families. It is higher and more vigorous than the trees in the inundated districts and has somewhat larger and longer seeds. Trees of more than 40 meters in height and up to five meters in circumference, are not rare. Whether the Acre fine rubber tree is a special species or a variety of Hevea Braziliensis, can be determined only by a very painstaking investigation. In yield of rubber and quality of product, the Acre tree surpasses that of the inundated districts. Of other Hevea varieties Hevea cuneata Hub. the Seringa vermelha, occurs but rarely, also sapium tapurú, Ule, is found but rarely. Castillôa Ulei, Warb., the “caucho” of the Peruvians, is quite plentiful and is generally utilized, its exploitation being regarded sometimes as more profitable than the fine rubber. Just as in the Amazon country, under the title “caoutchouc,” the product of castillôa is mainly understood, so, in Acre, for the yield of the Hevea, the name “fine rubber” is used. At present, there are on the Acre no unowned, unused lands, but some of the seringaes in operation are capable of further development. In lower Acre there are many seringaes that are badly exhausted and furnish but a small yield. The rubber collectors too, who, as is well-known, cut down the Castillôa trees, are compelled to go further into upper Acre all the time to find profitable work. Acre territory is regarded as the most productive fine rubber section, especially on its borders; on the little river Hapury and towards the Taurumano, which belongs to the water-shed of the Madeira, the output is said to be exceedingly rich. In proportion to their longitudinal extent, the extent of the woods belonging to Acre, in breadth, is comparatively small, for in a one or two days’ journey, it is possible to reach the district of another river. The rubber forest properties are consequently all measured from the river and include usually, a territory of several hundred square kilometers, often in fact, equal to small principalities. Many owners have also several seringaes, often in Bolivia and Brazil simultaneously. In such a seringal on the river bank, the dwelling with warehouse accommodations and sales-place, is erected, known as the Baracâo in contradistinction to the small Baraken of the work people. About the Baracâo the forest is usually cleared to afford land for planting and pasture for the cattle. The management of the seringal and its entire business, proceeds from the Baracâo. According to the extent of the seringal, from twenty to several hundred work people are employed on it. Through the entire forest, paths, known as =estradas=, are laid out, from which all obstructive brush and hanging creepers, are cut away with the macheté. These =estradas=, where possible, are laid out in loops, so that they lead back to the starting point and are so planned as to include from 100 to 150 fine rubber trees.