ls, salt being an antidote.[134] We were not troubled
with sand-flies after leaving the plaias of the Napo, but the musquitoes
at Pebas were supernumerary. Perhaps, however, it was a special
gathering on our account, for the natives have a notion that just before
the arrival of a foreigner the musquitoes come in great numbers.

[Footnote 134: Urari is mentioned by Raleigh. Humboldt was the first to
take any considerable quantity to Europe. The experiments of Virchau and
Muenster make it probable that it does not belong to the class of tetanic
poisons, but that its particular effect is to take away the power of
voluntary muscular movement, while the involuntary functions of the
heart and intestines still continue. See _Ann. de Chim. et de Phys._, t.
xxxix., 1828, p. 24; and Schoemberg's _Reisen in Britisch Guiana_, th.
i., s. 441. The frightful poison, _tieute_ of India, is prepared from a
Java species of _strychnos_.]

Many of the Indians are disfigured by dark blotches on the skin, the
effect of a cutaneous disease very prevalent in Central Amazonia. Here
we first noticed the singular habit among the children of eating clay.
This habit is not confined to the Otomacs on the Oronoco, nor to Indians
altogether; for negroes and whites have the same propensity--Mr.
Hauxwell found it impossible to restrain his own children. Bates
ascribes the morbid craving to the meagre diet. This may be true to some
extent, but it is certainly strange that the extraordinary desire to
swallow earth (chiefly unctuous clays) is found only in the tropics,
where vegetation is so rank and fruit so abundant.

CHAPTER XVI.

Down the Amazon.--Steam on the Great River.--Loreto.--San
Antonio.--Tabatinga.--Brazilian Steamers.--Scenery on the
Amazon.--Tocantins.--Fonte Boa.--Ega.--Rio Negro.--Manaos.

We left Pebas for Tabatinga in the Peruvian steamer "Morona," Captain
Raygado. Going up to Jerusalem by railroad, or ascending the Nile by a
screw whisking the sacred waters, is not so startling as the sight of a
steamer in the heart of South America. There is such a contrast between
the primeval wildness of the country and the people and this triumph of
civilized life; and one looks forward to the dazzling future of this
great valley, when the ships of all nations will crowd the network of
rivers for the gold and perfumes, the gems and woods of this western
Ophir. The natives call the steamer the "devil's boat," or "big canoe;"