30 RUBBER AND 



the Guayule rubber plant of the deserts of Northern 

 Mexico. The Guayule is a small shrub, rarely attaining 

 a height of four feet or a diameter of more than three 

 inches. The plant contains no latex, but granules of 

 true rubber occur scattered through the tissues, especially 

 those of the bark. The plants are gathered as a whole, 

 and the rubber is obtained partly by a mechanical 

 process of grinding and partly by chemical extraction. 

 The exact processes employed are kept secret. Guayule 

 rubber was only first placed upon the market about 

 1903, when the demand for rubber was beginning to 

 outrun the supply. By the end of 1909 the extraction 

 of the rubber was said to be one of the most important 

 industries of Mexico. The supply is however already 

 diminishing, and this source of rubber can scarcely be 

 regarded as a permanent one. 



AFRICAN RUBBERS. 



The Lagos Silk Rubber, Funtumia elastica, formerly 

 known as Kickxia africana, is a handsome tree some- 

 what resembling a coffee plant when young. This 

 rubber first came into notice in the colony of Lagos 

 in 1894. The trees are tapped on a herring-bone system, 

 and the latex collected in a vessel at the foot of the tree. 

 In some districts the latex is coagulated by boiling; 

 this method yields an inferior rubber owing to the 

 damage often caused by excessive heating. A second 

 method is to pour the latex into a tank excavated in the 



