THE HEVEA RUBBER TREE IN THE AMAZON VALLEY 39 
were girdled by a cut made through the bark to the wood. With 
some of the trees this had no effect on the yield whatever; in other 
cases there was an immediate decrease in yield, which in some trees 
was very noticeable. 
Later, in successive periods, girdles were cut, at higher and higher 
levels, so that they were nearer and nearer the tapping cut. Again 
the trees behaved differently. Some showed no decrease in yield 
until girdled very near the tapping cut. It may therefore be expected 
that the influence of the root will be great on some budded stock and 
of little significance in other cases. To secure the highest possible 
yields the stocks for budding should be grown from selected seed. 
The use of cuttings might insure uniformly high-yielding trees, 
but cuttings of Hevea are extremely hard to root. Out of hundreds 
of cuttings the writer was able to grow only one tree. Furthermore, 
there is some uncertainty as to the type of root system which will 
develop from a cutting. It is also impossible to take a great number 
of cuttings from a superior tree, while a single tree will supply a large 
number of buds. For the present at least, propagation by cuttings 
is not practicable for plantations. 
In addition to using the latest methods of propagation and plant- 
ing, a rubber plantation in South America would need at every step 
the advice of the best authorities obtainable. Anything like a boom 
development is almost certainly destined to fail. 
On account of the expense involved in securing experienced advi- 
sers, in importing labor, etc., organizations with small capital are 
not likely to succeed unless a considerable number of them form an 
association, so that the costs may be distributed. 
In some cases it may be possible to combine the collection of wild 
rubber with the development of plantations. If cheap labor could 
be procured for the plantation, it could also be used for collecting 
rubber, and with improved methods of tapping and collection and 
with better freight rates the wild rubber reserves might become a 
substantial asset to the plantation. 
The slight development of agriculture in general in the Amazon 
country increases the difficulty of establishing rubber plantations. 
The agricultural possibilities of this region are truly great, and when 
they are even partially developed a large population will be able to 
live on the products. Such magnificent areas as the Acre district 
should not long remain unused. The possibility of combining rubber 
growing with the planting of other crops should not be overlooked. 
THE LOWER AMAZON REGION * 
From the trees examined in the lower Amazon region one is not 
favorably impressed with plantation possibilities there. Most of the 
old trees, it is true, have been exploited for a long time and have been 
subjected to great abuse, so that one would not expect them to be 
in very good condition. Such trees as have been planted have in 
nearly every case received so little care as practically to guarantee 
their failure. 
At the Campo de Cultura Experimental Paraense, near Para, a 
considerable number of Hevea trees have been planted, some of 
them as early as 1910. None of these trees have made a satisfactory 
4 This section refers only to the land which lies immediately along the river and not to the extensive 
areas south of the river which are reported to be suitable for rubber cultivation. 
