25 7 
volume of latex between young and old trees is considerably higher 
in old trees ; thus : — 
No. of Trees. 
Total Girth. 
Latex. 
Dry Rubber. 
Young Trees. 
90 
220' 5" 
3511 
37 lbs. 
120 
276' IOf" 
3433 
43 „ 
100 
^76' ror 
3981 
48 „ 
Old Trees 
50 
209' 4 l" 
3323 
75 „ 
In previous reports we have called attention to the necessity of 
wide planting as the most important factor in the annual increment 
of growth of rubber trees. Such increment, we consider, should not 
be less, for the average of an estate, than two inches per annum be- 
tween the third and thirtieth years. 
The increment of growth of para trees is variable according to 
situation, soil, humidity ; but the ratio of increment also varies ac- 
cording to the age of the tree, thus : 
5 years old 
5 „ 
16 „ 
28 „ 
1904 1905 
1 ' 5 H" 1 ' 9 l /z 
1' 6 %" 1' 11^" 
3 ' 9 W 3 ' nH’ 
9 Wz 9’ 3H" 
We would estimate the ratio of 
ditions are fair as follows : — 
Increment 
1906 1909 6 years 
2' i%" 2' n%- = 1' sH" 
2 ' 3 ' Wa -■ 1 ' 6 ^" 
4 ' 3 " 4 ' 10M" 1' 1" 
9 ' SVa " 10' 0 y 2 " o' II" 
growth where the general con- 
From 5 to 15 years - - 3 to 4 inches per annum. 
„ 15 „ 20 „ - - - 2 „ 3 „ 
„ 20 „ 30 „ - - - i „ 2 „ 
The normal increment of growth, however, may be modified in 
any particular year through prolific seeding. It has been ascertained 
with oaks and beeches in temperate countries that the annual 
concentric ring of new wood may be reduced as much as 50 per cent 
as a result of heavy seeding. 
There is a far more important cause which checks the normal 
growth of Para trees when overcrowded. With trees in general there 
is usually some excess of food assimilated which gradually accumu- 
lates until exhausted or disposed of by a heavy crop of seeds ; but in 
rubber trees regularly tapped, the plant food formed by the tree has 
not only to provide the formative substance of a seed crop -as well 
as find nutriment for the cambium zone, but it has also to furnish 
material for new cell wails which are regularly formed as tapping 
proceeds. To meet this extra demand well developed trees with 
abundance of leaves — really manufacturing organs are necessary, but 
as a consequence of overcrowding and the resulting struggle for ex- 
istence a small crest of leaves manages to reach the light and such 
diminished organs are incapable of elaborating the necessary food. 
It does not appear to us that such trees suffer directly as latex- 
producers. All our observations and experiments tend to show that 
