808 The Philippine Journal of Science 1917 - 
larger individual trees showed a slow rate of growth and others 
of the same species a rapid rate. 
Realizing the above objections, we have, in order to compare 
the data obtained from the trees on the Gedeh with those grow- 
ing in other regions, treated them as though the age of the 
forest could be determined from them. To do this we have 
calculated the number of years required for the average of all 
the trees of a given diameter class to grow 10 centimeters or 
in other words to pass through the 10 centimeters diameter 
class. As the smallest diameter class was from 10 to 20 centi- 
“meters we calculated the age of the trees as beginning with a 
diameter of 10 centimeters, and by adding together the number 
of years required for trees to pass through the successive dia- 
meter classes, arrived at figures, which for purposes of com- 
parison can be regarded as the ages of trees of given diameters 
of from 20 to 70 centimeters. These results are plotted in™ 
fig. 1 in which the ordinates represent diameters and the ab- 
scissae years. This treatment is justified to some extent by 
the fact that most of the trees are very much smaller than the 
maximum size given by Koorders* in his Exkursionsflora, while 
only one individual of one species, Symplocos costata, has ob- 
tained the maximum size. This individual, however, showed 
a faster rate of growth than the average of its diameter class. 
In the same figure are also plotted the average rates of growth 
for a large number of species on Mount Mariveles, Philippine 
Islands, at altitudes between 400 and 500 meters and the average 
rates of growth of five representative species in the northern 
Laguna forest, Philippine Islands.’ In the same figure we have . 
plotted the rates of growth of yellow poplar in Virginia and 
Tennessee and of white oak in Tennessee and Kentucky.* The 
original figures for yellow poplar and white oak were in inches. 
In order to make these figures comparable with our results, we 
converted the inches into centimeters and plotted them on co- 
ordinate paper. From these curves we obtained the numbers 
used in plotting the curves in figure 1. 
An examination of figure 1 shows that the rates of growth 
obtained on the Gedeh are riot very different from those for 
white oak and yellow poplar and for the species in the forest of 
northern Laguna. The figures obtained for rates of growth on 
the Gedeh cannot, of course, be regarded as final, except for ae 
‘ Koorders, S. H., Exkursionsflora von Java (1911-1912). 
* Brown, W. H., and Matthews, D. M., op. cit. 
* Graves, H. S., and Ziegler, BE. A. The woodman’s handbook, U. S. 
Forestry Service Bull. 36 (1910) 189, 190. 
