202 RUBBER AND 



15 by 15 feet in more than one district in Ceylon, and 

 growth has been very rapid for the first two years. 

 At the end of this time the branches met and formed 

 a close cover, with the result that subsequent growth 

 was very slow. 



The structure of the laticiferous system of Manihot 

 is closely similar to' that of Hevea. The Manihots are 

 the only other rubber-producing plants upon which 

 tapping can be carried out at an equally short interval, 

 and although the study of the subject has not been 

 carried so far as in the case of Hevea, the phenomenon 

 of wound-response seems to be closely similar in both. 



Another advantage of Ceara rubber is that the plant 

 grows like a weed, so that trees which have been injured 

 in the course of tapping can be replaced with very little 

 trouble. 



On plantations, the hard outer bark is generally 

 removed before tapping. Opinions differ as to whether 

 tapping should take place immediately after the outer 

 bark is removed or whether it should be delayed for 

 a longer or shorter period. In Africa the method of 

 tapping usually adopted is the primitive one of pricking 

 or stabbing with a blunt thin-bladed knife. The pricks 

 are made about an inch apart in a vertical series. Some- 

 times the bark is first rubbed over with a freshly cut 

 lime or lemon, in order that the latex may be coagulated 

 on the bark by the citric acid thus applied. The strips 

 of wet rubber formed upon the bark are collected by 

 rolling them up on sticks or small wooden rollers. 



