ELASTIC GUMS iad 281 
much too small to be of any economic significance. The 
use of this juice to the plant is not altogether clear; but from 
the fact that it flows readily from a cut and after a little while 
hardens upon exposure to the air, the conclusion seems war- 
ranted that it serves in part at least as a ready means of 
Fic. 270.—Brazilian Rubber-tree (Hevea guyanensis, Spurge Family, 
Euphorbiacee). A, flowering branch. . ower-cluster. C, 
staminate flower. D, same with calyx removed. EE, pistillate flower, 
with calyx removed. (Berg and Schmidt.)—Tree growing 20 m. tall; 
leaves thin: flowers inconspicuous; fruit somewhat fleshy. Native 
home, Brazil. 
covering wounds promptly with a waterproof protection 
against agencies of decay. 
One of the most important American sources of caoutchouc 
‘s the Brazilian rubber-tree (Fig. 270). Long before the 
coming of Europeans the South American Indians made use 
