THE AFRICAN RUBBER VINES 193 



in diameter at the base and over 300 ft. in length. L. 

 owariensis also grows to a large size, but does not 

 quite reach the dimensions of the two species just 

 mentioned. 



Collection of the Rubber. — The methods generally- 

 adopted by the natives for preparing rubber from these 

 plants may be grouped mider the following heads : 



(1) By making incisions in the steins and allowing the 

 latex to coagulate spontaneously in the cuts. — In a number 

 of cases the latex of rubber vines does not flow freely, 

 and when incisions are made in the stems the latex simply 

 exudes into the cuts and there coagulates. Sometimes 

 the vine is tapped as it hangs on its supporting tree, 

 the native climbing amongst its spreadmg branches for 

 the purpose ; in other cases the main stems of the vine 

 are severed as high as possible and are then pulled down 

 from the tree, laid along the ground, and tapped in that 

 position. Whichever method is adopted, the native 

 usually makes numerous mcisions on every available 

 stem, both large and small, the cuts being often of 

 considerable size. 



When the latex is so thick that it only fills the mcisions 

 without overflowing, coagulation takes place very quickly, 

 and after a short interval the strips of rubber can be 

 pulled from the cuts. In other instances, however, the 

 latex flows a little more freely for a short time, so that a 

 small quantity runs from the cuts, and in order to prevent 

 the loss of this portion it is collected in a vessel or on 

 a leaf, and is spread out in a thin layer to hasten its coagula- 

 tion ; or it is received in the hand and smeared on the 

 chest and arms of the collector, where it quickly coagu- 

 lates. Other methods which are employed in such 

 cases are to cut off a long slice of bark, exposing the wood, 

 and to spread out the latex in a thin layer on the surface 

 thus obtained, or to smear the wound with a coagulant 

 such as a solution of salt or an acid liquid. 



The strips of rubber thus obtained are usually made 

 into baUs of varying sizes, which are loiown in the 

 market as " niggers." GeneraUy the balls are formed 

 by the natives at the time of stripping the rubber from 

 the mcisions. Sometimes, however, the natives coUect the 

 rubber in a loose mass, and afterwards wash it in warm 

 water to remove the fragments of bark as far as possible 



