ELASTIC GUMS 



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 



Fig. 270. — Brazilian Rubber-tree {Hcuea fjuyunensin, Spurge Family, 

 Euphorbiacecr) . A, flowering branch. B, part of flower-cluster. C, 

 staminate flower. D, same with calyx removed. E, 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 

 is the Brazilian rubber-tree (Fig. 270). Long before the 

 coming of Europeans the South American Indians made use 



