XIV, 5 Yates: Grpwth of Hevea Brasiliensis 517 
has not been found practicable to apply any correction for this 
difference due to height of measurement; but when comparing 
the girth of trees measured at different heights, the fact should 
be borne in mind that such difference exists and that it increases 
with the size of the tree. 
In fig. 1 is plotted the average circumference of trees of the 
various ages measured, and from this curve the average circum- 
ference of trees from 1 to 10 years old has been calculated. The 
results obtained in this manner are given in Table XI. 
TABLE XI.—Diameters attained by average trees in Basilan. From 1 to 10 
years old with increment. 
Aevinyean, | Greene | Tee 
| 
cm, cm, 
12 ee eee | 10.3 10.3 | 
BIS os ol Behe 18.7 8.4 
ee eee oe ee Paes 5 | 8.5 
oe es ae ies 35.6 8.4 
SSS ase | 44.0 8.4 
Cree Se ee bo §a4 8.4 
Ue oo ies ae es | - 60.9 8.5 
Bet SL SEO Aa OS | 69.4 8.5 
Os ee st ae po Te 8.5 
$0 ar eh pe a ee | 86.5 8.6 
Age in months. 
10 20 30 40 50 60 70 80 $0 00 “a 120 
ee of 
\ 
a re 
Circumference in centimeters. 
(\ 
. ae 
a aig Or 
“|.-“Fre ‘ 
"a 
Fie. 1. Comparison of the growth of Hevea brasiliensis in the Philippine Islands with 
that in Ceylon and Malaya. 
