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234 ' FOXWORTHY. 
luinened, mostly isolated vessels of various diameters (0.07-0.105 itun) 
and broader 3-5-rowed pith-rays. The vessels have simple pits and 
on the walls in contact with pitli-ra}'' parenchyma^ a transition from 
typical bordered to simple pitting. The wood parenchyma is richly devel- 
oped. The wood prosenchyma in Shorea and Ilopea has only veiy small^ 
often indistinct^ bordered pits; t3^pical bordered pitting is shown on the 
contrary in Dipterocarpus and Vatica, Accoi'ding to Brandis and Gilg, 
the pitting in the genus Dipterocarpus is not constant. According to 
BrandiSj diaphragming of the wood prosenchyma occurs in Pentacmc. 
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. 
Barl: — The bark of most, and perhaps of all, species shows the 
P3Tamidal arrangement of bast so well known in Tilia. Vascular bundle?, 
resin-canals, and mucihage-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 nenally mnch more membranaceous than are those of 
mature trees and are usually of much larger size. Venation ^ simply 
pinnate. Secondary nerves often parallel. Tertiaiy 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 Ilopea basUanica, II. mindanensis, II. phiUp- 
pinensis, II. plagala, II. pkrrei, 11. ovalifolia, Shorea tcysmanniana, 8. 
sqmmaia 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 KKATURES. 
Brandis, /. c. G/has called attention to the frequently gregarious habit 
of this family, and has compared the Dipterocarpwceae, in this respec , 
to the conifers of the temperate regions. A few of the Philippine 
species, notably Vatica spp., do not seem to have this peculiarity to am 
"Throughout this p^per, I have followed Brandis, /. c. in the use of teim^ 
referring to the venation. Tlie midrib is considered as the primary nerve, ^^ 
first hranches from it, the Heeondnry nerves, etc. Xerve and vein are "^''* 
synonymous. 
