ASSIMILATIVE AND SECONDARY RUBBERS 135 



Palo Amarillo. This is a species of the almost 

 numberless Euphorbia which abound in Mexico and 

 Brazil. It is a handsome, attractive tree, and con- 

 siderable attention was paid to it by a wealthy 

 American company operating two years ago in the 

 districts affecting the various Plumierias and root 

 rubbers of Mexico, with a view to discovering a 

 really serious competitor of the costly Guayule. 

 But Professor Ohlsson Seffer, who was retained by 

 the Mexican Government to determine and classify 

 the several economic plants of the country, was able 

 to show that Palo Amarillo must be placed very 

 low down in the scale of rubber-yielding trees. 

 Nevertheless the plant is being actively exploited, 

 together with other Euphorbias such as the Chupire 

 and the Vara Leche, and Jatrophas like the curcas 

 and urens and many Plumierias of high yielding 

 quality. The output from these inferior rubbers 

 has been placed by American experts at over 2000 

 tons for 1910. 



Ecanda or B'tinga, known on the Continent as 

 N'tinga. This is a bulb rubber from Angola, Por- 

 tuguese West Africa. Its botanical name is 

 Raphionceme utilis. It was originally found at an 

 elevation of nearly 5000 feet, thickly studding the 

 whole of a vast plateau near Bihe, on the road from 

 Benguella to Lake Tanganyika. The tubers, which 

 are an annual, weigh from 4 Ib. to 5 Ib. each, and 

 contain, it is said, a very high percentage of excel- 

 lent rubber. Experiments at Kew and Berlin go 

 to show that the plant is easy of cultivation, and 

 would be likely to prove of economic value if planted 



