The cotton and cane-sugar are grown in the middle coast region. The cotton industry bids fair to add materially to the prosperity of the state. A considerable part of the raw cotton is exported, but the reserve is sufficient to keep ten thousand looms busy. About three hundred and fifty million pounds of the raw sugar is purchased by the refineries of the United States, and much of the remainder by British dealers. The seeds of a species of myrtle (_Bertholletia excelsa_) furnish the Brazil nuts of commerce, large quantities of which are shipped to Europe and the United States.[65] Manganese ore is also an important export, and Great Britain purchases nearly all of it. The coffee-crop of the southern states is the largest in the world; and about eight hundred million pounds are landed yearly at the ports of the United States. The coffee-crop, more than any other factor, has made the great prosperity of the state; for while the rubber yield employs comparatively few men and yields but little public revenue, the coffee-crop has brought into Brazil an average of about fifty million dollars a year for three-quarters of a century. Cattle products also afford a considerable profit in the vicinity of the coffee-region. The hides and tallow are shipped to the United States. For want of refrigerating facilities, most of the beef is "jerked" (or sun-dried), and shipped in this form to Cuba. The facilities for transportation, the rivers excepted, are poor. The Amazon is navigable for ocean steamships nearly to the junction of the Ucayale. The Paraguay affords a navigable water-way to the mouth of Plate River. Rapids and falls obstruct most of the rivers at the junction of the Brazilian plateau and the low plains, but these streams afford several thousand miles of navigable waters both above and below the falls. Nearly all the railways are plantation roads, extending from the various ports to regions of production a few miles inland. The most important railway development is that in the vicinity of Rio, where short local roads to the suburban settlements and the coffee-plantations converge at the harbor. About fourteen thousand miles of railway are completed and under actual construction. A considerable part of the mileage is owned and operated by the state, and it has become the policy of the latter to control its roads and to encourage immigration. One result of this policy is the increasing number of German and Italian colonies, that establish settlements in every district penetrated by a new road.