234 
FOXWORTHY. 
lumened, mostly isolated vessels of various diameters (0.07-0.105 mm ) 
and broader 3-5-rowed pith-rays. The vessels have simple pits and 
on the walls in contact with pith-ray parenchyma, a transition from 
typical bordered to sim'ple pitting. The wood parenchyma is richly devel- 
oped. The wood prosenchyma in Shorea and Hopea has only very small, 
often indistinct, bordered pits; typical bordered pitting is shown on the 
contrary in. Dipterocarpus and Vatica. According to Brandis and Gilg, 
the pitting in the genus Dipterocarpus is not constant. According to 
Brandis, diaphragming of the wood prosenchyma occurs in Pentacme. 
In the older wood, the same substances as are contained in the resin- 
canals, are also present in the pith-rays, in the vessels and in the wood- 
parenchyma.” 
Baric . — The bark of most, and perhaps of all, species shows the 
pyramidal arrangement of bast so well known in Tilia. Vascular bundles, 
resin-canals, and mucilage-cells are present in the bark of some species. 
Leaves . — The leaves are often coriaceous and contain resin-canals. 
Usually entire, sometimes with serrate or dentate margins. The leaves 
of seedlings are usually much more membranaceous than are those of 
mature trees and are usually of much larger size. Venation 5 simply 
pinnate. Secondary nerves often parallel. Tertiary nerves sometimes 
clothed with stellate hairs, and the space between them also sometimes 
clothed with simple, stellate or peltate hairs or scales. 
Domatia are' present in Hopea basilanica , II. mindanensis, H. philip- 
pinensis, II. plagata , II. pierrei, II. ovalifolia, Sliorea teysmanniana, S. 
squamata and other species. The exact, structure and function of these 
domatia is not well understood. 
Stomata are said to be found only on the under side of the leaf. 
The petioles are usually thickened for a part of their length and con- 
tain a number of vascular bundles and resin-canals, the arrangement of 
which is of some systematic importance. 
The stipules are often of small size and early deciduous. They are 
usually most prominent on seedlings. The twig is completely encircled 
by the stipule-scar in Parashorea and Dipterocarpus. > 
BIOLOGICAL FEATURES. 
Brandis, l. c. 6, has called attention to the frequently gregarious habit 
of this family, and has compared the Dipterocarpaceae , in this respect, 
to the conifers of the temperate regions. . A few of the Philippine 
species, notably Vatica spp., do not seem to have this peculiarity to any 
5 Throughout this paper, I have followed Brandis, 1. c. in the use of terms 
referring to the venation. The midrib is considered as the primary nerve, the 
first branches from it, the secondary nerves, etc. Nerve and vein are used as 
synonymous. 
