PHILIPPINE DIPTEROCARPACEAE. 
233 
Pith. — The pith is heterogenous, the greater part of it being made 
up of thin-walled cells. In some cases, mucilaginous cells are found. 
Eesin-canals occur either in the center or the periphery of the pith. 
Their number and arrangement has some value as a taxonomic character. 
Wood. — The wood is characterized by the presence of resin-canals and, 
frequently, a large amount of wood parenchyma. The resin-canals do 
not seem to show any very regular arrangement. In some forms (species 
of Pentacme , Shores Hopea , Parashorea) , they are abundant and form 
noticeable whitish rows, which are incompletely concentric and occur at 
irregular intervals. They present a whitish appearance, because of the 
contained resin, and give an appearance like that of seasonal growth 
rings. In some cases (species of Anisoptera and Dipterocarpus) , the 
resin-canals are filled with oil, which causes them to be less readily 
distinguished. In these cases, the oil flows out and covers the stump 
when the tree is cut, making the stump and the butt of the log very 
gummy. 
In Vatic a wood, the resin-canals are much less prominent than in those 
forms already mentioned. The wood elements are rather finer and 
very regular in arrangement. 
The color of the wood of Vatica and the species of Shorea and Hopea 
which are known as yacal or dalindingan , is a yellow-brown when first 
cut, becoming much darker on exposure to the air. 
Many species of Shorea ( S . polysperma, S. teysmanniana, S. negro- 
sensis , etc.) have wood of a fine clear red color. S. squamata , S. 
eximia and Parashorea plicata have wood which is much lighter in color, 
but which may occur darker or which may darken to the color of S. 
polysperma. It is most often, however, of the same color as the sapwood 
of that species. Pentacme contorta has wood of a dull-gray or faint- 
brownish color. Some Slioreas {S. guiso , etc.) have hard, fine-grained, 
light grayish or reddish wood, with a very abundant development of wood- 
parenchyma. 
In all reddish dipterocarp woods the color fades badly on prolonged 
exposure to the air. 
Some species of Anisoptera and, possibly, some Shoreas, which have 
a pale-yellow wood, show a pale-rose tint in the freshly cut wood. 
In hardness, the wood is very variable, ranging all the way from the 
very soft wood of Pentacme and some of the Shoreas, to the very hard 
wood of some of the Hopeas, Shoreas, and V'aticas. The hardness of 
these latter seems to be due principally to the thick cell-walls. 
The following statements concerning the minute anatomy of the wood 
are taken from Solereder : 4 “The cross-section of the wood shows round • 
* Solereder, H. Systematische Anatomie der Dicotyledonen (1899) 157. 
