THE HEVEA RUBBER TREE IN THE AMAZON VALLEY 
59 
ceded by all investigators of the qualities of rubber. It is possible, 
however, that it is especially suitable for certain uses and that such 
uses coupled with its comparative scarcity account for its market 
price. 
SOURCES OF CAUCHO 
The caucho of the Amazon Valley is obtained from species of Cas- 
tilla, probably principally from Castillo, ulei (fig. 12). These trees 
grow on high ground above the high-water level of the rivers. They 
are large and grow to approximately the same height as those of 
Hevea brasiliensis. In girth, too, they approach the Hevea trees, 
though the writer found none so large as the largest Hevea seen. 
Fig. 13. — The trunk of the caucho tree shown in Figure 12 tapped by a cut through the bark and 
extending entirely around the tree. Cuts like this are made about 4 feet apart along the whole trunk 
of the tree. The latex is usually collected in a hole in the ground, but sometimes vessels are used, 
as shown here 
Since the trees grow on the uplands, most of them are found far 
up the rivers, and caucho cutters usually have to ascend the rivers 
much farther than the seringueiros to find profitable areas. As the 
tree is killed in the process of obtaining caucho, all of the trees of 
any size have disappeared from the uplands along all of the lower 
river courses. The process of extermination is going on rapidly, 
with the result that every year the collectors must go farther afield. 
Judging by the number of trees which have been cut yearly for a 
considerable time, the day is not far distant when all the caucho trees 
in the areas which can be reached by the present means of transporta- 
tion will be destroyed. 
METHOD OF COLLECTIXG 
The latex is collected from caucho trees by felling them and then 
cutting rings around the trunks which, extend through the bark to the 
wood. These cuts are made between 1 and 2 meters apart (fig. 13). 
