from which point I imagined the
river must be slightly better known. Therefore, as I should be busy all
day long with the prismatic compass and watch, constantly taking notes of
the direction of the stream and the distances covered (checked almost
daily by astronomical observations) I should not be able to take an
active part in the navigation.

The canoe was undermanned. Imagine her length--42 ft.--with only two men
to paddle. A third man was stationed on her bow to punt when possible and
be on the look-out for rocks; while Alcides, whom I had promoted to the
rank of quartermaster, was in charge of the steering. I had taken the
precaution to make a number of extra paddles. We carried a large quantity
of fishing-lines with hooks of all sizes, and cartridges of dynamite.

The river was most placid and beautiful, and the water wonderfully clear.
Unlike rivers elsewhere, the Arinos did not show a branch or a twig
floating on its waters, not a leaf on its mirror-like surface. That did
not mean that branches of trees--sometimes even whole trees--did not fall
into the river, but, as I have stated already, the specific gravity of
woods in that part of Brazil was so heavy that none floated. Hence the
ever-clean surface of all the streams.

We were then in a region of truly beautiful forest, with _figueira_
(_Ficus_ of various kinds), trees of immense size, and numerous large
_cambara_. The bark of the latter--reddish in colour--when stewed in
boiling water, gave a refreshing decoction not unlike tea and quite good
to drink.

Most interesting of all the trees was, however, the seringueira
(_Siphonia elastica_), which was extraordinarily plentiful in belts or
zones along the courses of rivers in that region. As is well known, the
seringueira, which grows wild in the forest there, is one of the most
valuable lactiferous plants in the world. Its latex, properly coagulated,
forms the best quality of rubber known.

[Illustration: Rubber Tree showing Incisions and the Collar and Tin
Cup for the Collection of the Latex.]

[Illustration: Coagulating Rubber into a Ball.]

There are, of course, many latex-giving plants of the _Euphorbiae_,
_Artocarpae_ and _Lobeliae_ families, but no other are perhaps such
abundant givers of latex as the Brazilian seringueira (of the
_Euphorbiae_ family), a tree plentiful not only in Matto Grosso on all the
head-waters and courses of the rivers flowing into the Amazon, but also
abundant in the Pro