ct quantity of light, warmth,
and moisture it requires, can be understood only by those who have seen
clusters of them hidden in the deep shade of the tree-crowns, while
others are exposed to the scorching rays of the sun in the vicinity of a
river or in some clearer part of the forest; some species thriving on
the bare rock almost, and others clinging fast with their white rootlets
to the moist rotting bark of a tree....

But of far greater importance to the half-civilized riverines than
either palms or orchids, for whose beauties they have no eye, are the
cacao and the caoutchouc-tree (_Siphonia elastica_), products of the
virgin forest essential to the future prosperity of the whole country.

Although India contributes to the supply of caoutchouc, the precious
resin which is transformed into a thousand different shapes every year
in the factories of Europe and North America, and sent to the ends of
the earth, it cannot compete with Brazil, which takes the first place
among the rubber-producing countries, in respect as well of the vastness
of its export of the material as of its superior quality.

On the shores of the Amazon its production, it is true, has already been
diminished by unreasonable treatment of the trees; the idea of replacing
the old ones by young saplings never having presented itself,
apparently, to the mind of the indolent population; but the seringaes,
or woods of rubber-trees, on the banks of the Madeira, the Purus, and
other tributaries of the main river, still continue to furnish
extraordinary quantities of it. The province of Amazon alone exports
more than fifty thousand arrobas (one million six hundred thousand
pounds) yearly, while the total of the exports of the whole basin
slightly exceeds four hundred thousand arrobas, or twelve million eight
hundred thousand pounds, per annum....

Unfortunately, there has not been until now the slightest attempt made
to cultivate this useful tree; and all the caoutchouc exported from Para
is still obtained from the original seringa groves. The trees of course
suffer, as they naturally would under the best of treatment, from the
repeated tapping and drawing-off of their sap, and the rubber
collectors, therefore, must look about for new groves of the tree in the
unexplored valleys of the more distant interior.

The planting of the _Siphonia elastica_ would be a more profitable
investment, as it yields the precious milk in the comparatively short
space o