States Army flannel shirts and a couple of silk shirts, one pair of hob-nailed shoes with leggings, and one pair of laced leather boots coming nearly to the knee.  Both the naturalists told me that it was well to have either the boots or leggings as a protection against snake-bites, and I also had gauntlets because of the mosquitoes and sand-flies.  We intended where possible to live on what we could get from time to time in the country, but we took some United States Army emergency rations, and also ninety cans, each containing a day’s provisions for five men, made up by Fiala.

The trip I proposed to take can be understood only if there is a slight knowledge of South American topography.  The great mountain chain of the Andes extends down the entire length of the western coast, so close to the Pacific Ocean that no rivers of any importance enter it.  The rivers of South America drain into the Atlantic.  Southernmost South America, including over half of the territory of the Argentine Republic, consists chiefly of a cool, open plains country.  Northward of this country, and eastward of the Andes, lies the great bulk of the South American continent, which is included in the tropical and the subtropical regions.  Most of this territory is Brazilian.  Aside from certain relatively small stretches drained by coast rivers, this immense region of tropical and subtropical America east of the Andes is drained by the three great river systems of the Plate, the Amazon, and the Orinoco.  At their headwaters the Amazon and the Orinoco systems are actually connected by a sluggish natural canal.  The headwaters of the northern affluents of the Paraguay and the southern affluents of the Amazon are sundered by a stretch of high land, which toward the east broadens out into the central plateau of Brazil.  Geologically this is a very ancient region, having appeared above the waters before the dawning of the age of reptiles, or, indeed, of any true land vertebrates on the globe.  This plateau is a region partly of healthy, rather dry and sandy, open prairie, partly of forest.  The great and low-lying basin of the Paraguay, which borders it on the south, is one of the largest, and the still greater basin of the Amazon, which borders it on the north, is the very largest of all the river basins of the earth.

In these basins, but especially in the basin of the Amazon, and thence in most places northward to the Caribbean Sea, lie the most extensive stretches of tropical forest to be found anywhere.  The forests of tropical West Africa, and of portions of the Farther-Indian region, are the only ones that can be compared with them.  Much difficulty has been experienced in exploring these forests, because under the torrential rains and steaming heat the rank growth of vegetation becomes almost impenetrable, and the streams difficult of navigation; while white men suffer much from the terrible insect scourges and the deadly diseases which modern science has discovered to be due very largely