320 The Philippine Journal of Science ma 



VATICA MANGACHAPOI Blanco. Narig. (Plate 10.) 



Gross features. — Sapwood light yellowish, thick; heartwood 

 yellowish when first exposed, turning to russet with age. Wood 

 the finest textured of any of the dipterocarps, fairly straight 

 grained, very hard and very heavy; specific gravity, 0.878 to 1.03. 



Microscopic features. — Vessels numerous, rounded in trans- 

 verse section, from 23 to 1'50 /* (average, 80) in diameter; tyloses 

 numerous, sclerosed, with simple pits. Tracheids and fiber 

 tracheids wanting. Libriform fibers radially arranged, 18 by 

 1,340 n, rounded in transverse section, lumina small; wall 

 approximately 7.5 /* thick. Vertical parenchyma vasicentric 

 and diffuse; gummy infiltration products globular. Resin cysts 

 diffuse, one-third to one-half the size of the pores. Idioblasts 

 strictly horizontal, 3C very conspicuous. Wood rays straight, 

 broad, 4 or 5 by 55 cells in transverse section, ray parenchyma 

 filled with gummy, globular infiltrations. 



Remarks.— Vatica mangachapoi is widely distributed through- 

 out the Archipelago and is found from the Babuyan Islands 

 southward to Basilan. The heartwood in contrast to the 

 perishable sapwood is extremely durable and is largely employed 

 for railroad ties and other purposes where strength and dura- 

 bility are required. This species is sometimes mistaken for the 

 fine-textured yakals but can easily be separated from the latter 

 by (a) the diffuse character and small diameter of the pores 

 and resin ducts, (b) the absence of zonate concentric paren- 

 chyma, and (c) by the comparatively large sapwood. 



THE APITONG GROUP 



The apitong group is represented in the Philippines by 

 seventeen species, all of which are products of the genus Dipte- 

 rocarpus and constitute about 17 per cent of the total volume 

 of the Islands' forest resources. The woods are very similar 

 in their gross features and are not distinguished in the market. 

 Among the most-important species are D. grandiflorus, D. 

 pilosus, and D. vernicifluus. 



Gross features.— Sapwood grayish red when fresh, medium 

 thick; heartwood reddish, turning to reddish brown with age. 

 Wood hard, heavy; specific gravity, 0.587, Gardner, 0.879; 

 resinous, straight grained. Resin cysts prominent, diffuse. 



