5i6 
NOTES OF A BOTANIST 
CHAP. 
Pastasa, and many others. Other steamers ascend 
the Rio Negro as far as Sta. Isabel, collecting the 
rubber from its highest tributaries ; while others 
ascend the Tocantins, the Tapajoz, and the Madeira 
as far as their respective cataracts; while the Purus, 
which has no such obstructions, is navigated for a 
distance of 2555 miles from Para. 
All these lines of steamers are mainly supported 
by the rubber trade, and there is reason to believe 
that, if required, many times the quantity now 
exported could be obtained without difficulty. 
Although a large number of trees and climbers 
in all parts of the world produce rubber, it is 
generally admitted that none yet discovered pro- 
duce it of such good quality and so economically 
as the rubber trees of the Amazonian forests. Nor 
is there, in this region, any danger of the supply 
becoming exhausted, because it has been found 
that if the trees are cut down and then tapped at 
different points (as has been done under the 
expectation of getting a larger amount of rubber) 
a much smaller quantity can be extracted than can 
be obtained from the living tree in a single season. 
So long as the trees are not tapped during the 
flowering and fruiting season (when the flow from 
the bark is but scanty), it does not appear that the 
annual tapping in any way injures the trees, nor 
has it been noticed that any diminution occurs in 
successive years. As, therefore, the tree is a large 
and long-lived one, and in its native forests is 
freely reproduced by seed, we may consider that 
so long as the forests continue to exist the supply of 
this valuable product will be almost inexhaustible. 
One cannot but marvel at the extraordinary reserve 
