558 



RUBBER 



RUBBER 



six pounds (or less) a year on an average. The 

 rubber brings a lower price than Para. 



Ceara rubber (Manihot Glaziovii). 



The Ceara rubber, a tree allied to the tapioca 

 plant, is a native of the dry desert regions of Ceara 

 in Brazil, where there is annually a long spell of 

 drought during which not a drop of rain falls and 

 the soil becomes perfectly dry. Though it fre- 

 quently has been planted in the equatorial forest 

 region it has always failed, as a permanently wet 

 climate is quite unsuited for it ; but it might be 

 cultivated with success in sandy regions where 

 there is a fairly heavy rainfall for a few months 

 followed by a spell of absolutely dry weather. 

 Ceara rubber has been but little under cultivation 

 as yet. 



It is grown from seed but may be raised from 

 cuttings. The seed is small, rather flat arid dark 

 brown. It is borne in a small capsule like that of 

 Para rubber, only much smaller. Because of the 

 hardness of the testa of the seed it germinates 

 slowly, and it is usual to file off the end or grind 

 the angle before planting. The tree grows with 

 fair rapidity, and soon attains a large size in 

 suitable localities. It requires a sandy soil and 

 a dry climate. 



It is generally tapped in short cuts and the latex 

 allowed to coagulate on the tree and collected in 

 the form of scrap. However, it can be drawn off 

 in quantity as is Para rubber, and coagulated by 

 means of smoke. The rubber is of a poorer qual- 

 ity than Para rubber, but the tree is certainly 



worth cultivation in countries where the climate 

 is suitable. 



Assam rubber (Fieus elastiea). Pigs. 795-798. 



The Assam, or India rubber, is a native of 

 Assam and the Malay region, where it is found 



Fig. 796. Fims eiasliea, or Assam rubber tree, Sbowing 

 tapping system. 



Fig. 795. Ficus elastiea, or Assam rubber tree. Showing habit 

 and the characteristic way it attaches its roots to a log. 



growing either as an epiphyte on other trees for 

 part of its life, finally killing its host, or as a rock 

 plant on high precipices. It is well adapted for 

 cultivation in the rain-forests of the equator, but 

 it will also grow farther north than will Para 

 rubber. It is the well-known "rubber plant" of 

 the horticulturist. 



Assam rubber can be grown from cuttings, 

 which is the usual method, or from seed. The 

 seed is very small and should be grown in 

 boxes over water, as it may be destroyed by 

 ants. There are 1,000 to 1,200 seeds in an 

 ounce. Cuttings grow rapidly and may be 

 tapped in four years. It grows freely without 

 shade if planted close, but more rapidly under 

 partial shade. The tree sends out aerial roots, 

 some of which are usually removed, leaving only 

 those which in time may become suitable for 

 tapping. Eoots and stems are tapped with a 

 V-shaped cut, made with a gage, and a sharp 

 knife is drawn down the center of each arm of 

 theV. 



The latex is more difficult to coagulate than 

 that of Para. It can be coagulated by stirring, 

 or by extracting as much water as possible. 

 One system is to allow it to drop on mats below 

 the tree, where it coagulates and is afterwards 

 removed. The amount of latex produced varies 

 greatly. After heavy tapping the tree requires 

 to be rested for a year or two. The value of 

 this rubber is about the same as that of Central 

 American rubber. 



Ire or silk rubber {Funtumia elastiea). 



This tree grows to a very large size, and 

 takes many years to come to maturity. When 

 of sufficient size and age it produces rubber of 

 excellent quality, but few can wait the time 

 required for it to mature, which may be given 

 at 1 minimum of twenty years. It might be 



