FOREST TREES AND PRODUCTS OF THE TROPICS 217 
forest is the caoutchoue, or crude rubber. This mate- 
rial is called india-rubber because it came originally 
from India, and “ rubber ” because it was first used 
for rubbing out pencil-marks. Caoutchoue is the 
South American name. The great value of this sub- 
stance is mainly due to its impermeability and marvel- 
lous elasticity. It is produced in immense quantities 
by several species of trees throughout the tropics. 
It is the juice or milk of the tree, which is collected 
and prepared in many ways. 
The common rubber-tree, which is used so exten- 
sively as a pot-plant in our houses, which grows 
month after month without dropping its rich, glossy 
leaves, with its roots crowded in little pots, and with 
an amount of abuse that would kill many of our 
native plants, is none other than the rubber-tree of 
the East Indies which has yielded part of the rubber 
of commerce. | 
The greatest rubber port in the world is at Para, 
a large city at the mouth of the Amazon. It is the 
valley of the Amazon which produces a very large 
proportion of the best rubber of the world. 
The tree which yields South American or Para 
rubber is called Hevea brazilensis. The milk from 
which it is formed comes from ducts in the inner 
bark. The collectors are Indians, each of whom ear- 
ries a small ax ‘and a ball of adhesive clay. With his 
