86 R UBBEIl FORESTS OF NIC A RA G UA A ND SIERRA LEONE 



well-drained lands. B}^ cultivation this tree would probalily 

 equal the other low-valley varieties in quality and annual out- 

 put of rubber. It has the advantage that if one of its trunks is 

 deadened by excessive drainage of the sap, it has several other 

 live trunks from which to obtain supplies of rubber. Another 

 good variety is the mnnihot b(d(ino, locally known as the " arbolde 

 vaca " (cow-milk tree), a large^ hardy, indigenous kind found at 

 altitudes of 1,000 to 2,000 feet above the ocean. 



The annual yield of elastic material depends on the bulk of 

 the bast or lactiferous tissues that exist or that can be developed. 

 Some trees of 2 or 3 feet diameter and 35 to 50 feet tall Avill give 

 annually 20 to 40 pounds of good rubber. The quality of rul)- 

 ber depends largely upon the form of the cells composing the 

 bast, and in part in the process used to separate the elastic ma- 

 terial from the emulsion-like sap. Quality and quantity are 

 responsive to cultivation. 



According to ver}^ recent re[)orts from Nicaragua, the leaves 

 jdeld a purer juice, and more copiously, than the bast. If this 

 proves true, the sui)ply of rubber can be largely increased with- 

 out permanent injury to the tree. 



The shoots should be transplanted to a nursery when one 

 year old, and thence removed to their permanent place when 

 3 years of age, in roAvs— say, 64 Matapala, 81 Siphonia, and 100 

 Castilloa trees per acre. 



Cultivation consists in ditching the land so as to drain it at 

 will, keeping it moist without permitting water to stand. Keep 

 all undergrowth cut down and the land "'hilled up" around the 

 trees. Fell other varieties of trees and vines until they shade 

 but a very small part of the land. Commence during the sixth 

 or seventh year to collect rubber by small area incisions through 

 the bast, taking, if the trees have matured proper! \% 8 to 12 

 pounds of rubber from each tree bienniall}', but after tjie tree 

 is 12 years of age a sufficient quantity of sap could be annual!}' 

 extracted to yield 10 to 15 pounds of good elastic rubber. 



The two following modes of incision are preferable to other 

 processes : (1) Cut with a curved, sharp instrument channels 

 througli the lactiferous tissues similar to tliose made in pine 

 trees in turpentine orchards in the United States ; (2) drive 

 tubes cut from tlie internodes of bamboo (abundant in.Nica" 

 ragua) through tlie Ijast, first malving a slanting cut of a part of 

 the circumference of the tul^e, and drive the sharpened end, 1? 

 to 2 inches long, into the tree: then, when the collectiiig season 



