On the east of the Duida mountain a dense thicket of wild Cacao groves begins, and amidst these are found trees of the celebrated Bertholletia excelsa, the most vigorous of the productions of the tropical world[59]. Here the Indians collect the materials for their blow-pipes, colossal grass-stalks having joints above 18 feet long from knot to knot.[60] Some Franciscan monks have penetrated as far as the mouth of the Chiguire, where the river is already so narrow that the natives have thrown across it, near the waterfall of the Guaharibes, a suspension bridge formed of the twining stems of climbing plants. The Guaicas, a race of comparatively light complexion but of small stature, armed with poisoned arrows, forbid any farther advance towards the east. All, therefore, that has been put forward respecting the lake origin of the Orinoco is fabulous[61]. We seek in vain in nature for the Laguna of El Dorado, which is still marked in Arrowsmith’s maps as an inland sea 80 geographical miles in length. Has the little reedy lake of Amucu, from which the Pirara (a branch of the Mahu) flows, given rise to this fable? But the swamp in which the lake of Amucu is situated is four degrees of longitude to the east of the district in which the sources of the Orinoco must be sought. It was an ancient custom of dogmatising geographers to make all the larger rivers of the world originate in considerable lakes. To the lake forming the supposed origin of the Orinoco was transferred the site of the island of Pumacena, a rock of micaceous slate, the glitter of which, in the 16th century, played, in the fable of El Dorado, a memorable, and to deceived humanity often a fatal part. It is the belief of the natives, that the Magellanic clouds of the southern hemisphere, and even the fine nebulæ in the constellation of the ship Argo, are a reflection of the metallic brilliancy of the silver mountains of the Parime. The Orinoco is one of those rivers which, after many windings, seem to return back towards the region in which they took their rise. After following a westerly and then a northerly course, it runs again to the east, so that its mouth is almost in the same meridian as its source. From the Chiguire and the Gehette as far as the Guaviare the Orinoco flows to the west, as if it would carry its waters to the Pacific. It is in this part of its course that it sends out towards the south a remarkable arm, the Cassiquiare, but little known in Europe, which unites with the Rio Negro, (called by the natives the Guainia), and offers perhaps the only example of a bifurcation forming in the very interior of a continent a natural connection between two great rivers and their basins.