THE SYPHONIA ELASTXCA 
of the Rio Preto (a tributary of the Arinos). The Serra 
do Tombador was parallel nearly all along with the river 
Paraguay. 
Because of departing so late in the day from Diaman- 
tino, and the time we had wasted on the way with social 
compliments, we were able to go only twelve kilometres 
that afternoon. We halted near the shed of a seringueiro 
(rubber collector), at an elevation of 1,580 feet, close to 
the Chapesa, a streamlet flowing into the Agua Fria (cold 
water), which in its turn threw itself into the Rio Preto. 
It was muggy and warm during the night — minimum 
65° Fahrenheit — with swarms of mosquitoes. We were 
glad to leave the next morning, following a northwesterly 
course across a wonderfully beautiful meadow, with cir¬ 
cular groups of trees and a long belt of vegetation along 
the stream. It was then that I made my first acquaintance 
in Brazil with the seringueira (Syphonia elastica or Hevea 
brasiliensis) , which was fairly plentiful in that region. As 
we shall see, that rubber tree, producing the best rubber 
known, became more and more common as we proceeded 
north. 
In the cuts of rivers, soft, red, volcanic rock was ex¬ 
posed, with a surface layer of white sand and grey ashes 
in the flat meadow. The padding of earth was thin. 
Except close to rivers and in extinct craters where the 
accumulations of earth and cinders were often deeper with 
a good supply of moisture from underneath, the trees were 
feeble and anaemic. There again I was amazed to find 
how unstable and weak most trees were. One could knock 
them down with a mere hard push — as the roots had no 
hold in the ground, where they spread horizontally almost 
on the surface, owing to the rock underneath which pre¬ 
vented their penetrating farther than the thin upper layer 
of earth, sand, and ashes. If you happened to lean against 
a tree four or five inches in diameter, it was not uncommon 
to have the tree tumble down and you, too. The wood also 
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