THE HEVEA RUBBER TREE IN THE AMAZON VALLEY 25 
and consequently they did not thrive. It seems possible that where 
estradas are being tapped new trees could be interplanted between 
the mature ones and a certain amount of clearing around each could 
be done at little expense. The larger jungle tree's should be girdled, 
the smaller ones felled, and the undergrowth cut and burned. Beyond 
that the undergrowth would need cutting from time to time. The 
growth of these trees would be slow compared with plantation trees, 
but ultimately the estradas would be filled in with trees so close to 
each other that tapping could be done at low cost, and the cost of 
such plantings would be very low. Had this method been applied 
years ago the Amazon Valley might still be a strong competitor of 
the Orient in rubber production. 
HEIGHT OF THE TREES 
The trees on the lower Amazon are, for the most part, of medium 
height; most of them are under 15 meters. But on the more ele- 
vated alluvial soil, the so-called varzea alta, and on the high land of 
the upper rivers they grow to a much greater height. At Fazenda 
Palmaris a fallen tree in an estrada was measured and found to be 36.7 
meters from the ground level to the tips of the highest branches and 
18.3 meters to the base of the lowest branch. The circumference of 
this tree was 2 meters. A tree in another estrada near here measured 
36 meters from the ground to its highest twigs and 27 meters to the 
first branch. This tree was 206 centimeters in circumference. 
Although both these trees were of large girth, they were not taller 
than other Hevea trees around them, even though the latter were 
frequently more slender. Apparently in this region the top of the 
forest canopy was more or less uniformly 36 meters above the ground. 
Some trees, of course, notably the castanhas, or Brazil-nut trees, 
reach far above this canopy. 
The trees on the upper Madeira, the Guapore, the Mamore, the 
Beni, and the Madre de Dios Rivers are of approximately the same 
height as the foregoing, as are also the trees on the Acre, on the 
Tahuamanu in Bolivia, and on the upper Purus. Such heights of 
trees mean naturally that the trees in the Amazonian jungle are 
much more slender than those of the plantations in the East. 
These latter trees have had full light during their entire period of 
growth and on this account have headed much lower than shade- 
grown trees would or could. Those plantations where thumb-nail 
pruning has been practiced have developed trees of still lower stature. 
SHIPMENT OF RUBBER 
After the rubber is prepared the seringueiro has to deliver it at 
the barracao, where he is credited with its value minus deductions 
for loss of weight on drying, etc. Although estradas are located 
near a stream whenever possible, in many cases the rubber has to be 
transported for miles before a stream is reached. Such transporta- 
tion is naturally very expensive. 
From the barracao the rubber must be carried by launch, raft, or 
batelao to streams navigable by boats from Para or Manaos and then 
shipped to those markets. 
In the days of the expedition of Spix and Martius (38), from 1817 
to 1820, most of the Para rubber was said to come from the jungles 
near Para and the island of Marajo. Spruce (/fi) tells of the spread 
