RUBBER PLANTING 87 



partly removed by the e.g. weekly opening of the 

 vessels, and that this concentration... inhibits the further 

 production of raw material. In other words, tapping 

 stimulates the tree both to the production of the raw 

 materials for rubber and to the conversion of these into 

 rubber. With frequent tapping the raw materials are 

 produced faster than they can be converted; with less 

 frequent tapping the reverse is the case 1 ." It is scarcely 

 necessary to point out that the whole subject requires 

 further investigation from the chemical standpoint. 

 The actual figures obtained in the analyses are given 

 in Table XXIV. 



General considerations affecting yields. 



Given a uniform and moderate system of tapping, 

 the yield from a Hevea tree should increase steadily 

 with its age and girth. Too drastic tapping will 

 certainly reduce the rate of increase of yield, and may 

 even lead to a falling off in the absolute yield of latex 

 and of rubber. On the other hand, there is reason to 

 believe that the yield after a given number of years will 

 be greater from a tree which has been regularly tapped 

 in moderation than from one which has been left un- 

 tapped. It should be observed, however, that the 

 definite experimental evidence upon this point is very 

 limited. Assuming that moderate tapping stimulates 

 the tree to increased activity in the production of latex, 



1 Circulars R. B. G. Peradeniya, Vol. v. No. 16. 



