MANY OR SPECIAL PURPOSES 359 



flow of sap. Whether it is best for the tree re- 

 mains to be seen. A plan to prick the bark, 

 puncturing the net-veins but not going deep 

 enough to injure the cambium, is a perfect method; 

 but the collecting of the flow is the difficulty. 

 Such treatment would not hurt the trees, if done 

 on alternate days. It might go on for years. 



Tapping on rainy days and early in the morning 

 induce the greatest flow, for the heat of the sun 

 causes the juice to coagulate and stop the passages. 

 Young trees and trees too heavily drained yield 

 rubber of poor quality. So do the upper parts 

 of trunks and the limbs. Thes facts are known 

 to the greedy rubber gatherer, and it saves the 

 tree from many abuses. 



Para rubber comes from a tree called Hevea 

 Braziliensis, that grows wild in different parts of 

 the silvas of the Amazon, and in Peru, Bolivia, 

 and Guiana, a total area of millions of square miles. 

 Para is the port from which most of it is shipped. 

 Brazil furnishes the world about half of its rubber 

 supply exports amount to fifty-four million 

 pounds a year. Not all of this is Para quality. 



Because Hevea trees produce the highest 

 quality of rubber, they have been planted where 

 new plantations are desired. They are estab- 

 lished in the West Indies and Trinidad, and in 



