( 5 ) 
1. Improvement Fellings. 
It has been successfully demonstrated, in the 
Federated Malay States, that the gutta percha tree 
needs a considerable amount of light for its best 
development and that many individual trees do not 
flourish or are of slow growth simply because they 
are not so located as to get a sufficient amount of 
light, both from overhead and from the side. Trees 
that * have been overcrowded or shaded and have 
been freed by the cutting away of the overshadowing 
vegetation invariably show very much increased 
vigour. It has been found that a forest which 
contains a fair amount of natural regeneration of 
this tree can be gradually changed over to an almost 
pure gutta percha forest by a gradual removal of 
other species. Since 1902 some 15,000 acres of 
forests have been improved in this way. In a few 
cases it has been possible to combine the working 
of timber and firewood from other trees with the 
operation to improve the gutta percha. 
2. Hate of Growth. 
Gutta percha which is favourably situated grows 
very rapidly. Measurements that have been made 
of 2B2 trees in forest sample plots during a period 
of five years have shown an average girth increment 
of 1.57 inches per year and have indicated the 
following relationships between girth and age: — 
* Girth — inches. Age — years. 
12 
8.2 
24 
15.7 
36 
20.6 
48 
28.3 
60 
37.9 
