OF THE DIPTEROCARPACEZX, 49 
higher internode; this subdivision, however, does not take place 
in as regular and, so to say, elegant a manner as is the case in 
Dryobalanops lanceolata. 
For the petiole of D. aromatica, Burck claims a very remark- 
able feature, viz., that the 4 lateral ducts do not run through 
the entire length of the petiole, but lose themselves gradually in 
the intercellular spaces of the tissue, so that the ducts, which 
accompany the lateral nerves in the leaf, all branch off from one 
central resin-duct. This I am not able to confirm. Some of the 
lateral ducts are often indistinct, but, as a rule, I have been able 
to trace them through the entire length of the petiole. Nor am 
lable to agree with Burck's statement, endorsed by Heim, that 
in D. aromatica at the base of the petiole the curved band of 
vascular bundles is open towards the underside (* une courbe 
ouverte vers le côté inférieur du pétiole"). The large resin-duct, 
Which occupies the underside of the petiole, is surrounded below 
by a semicircle of xylem with an outside belt of phloóm, and the 
opening of this semicircle is towards the upperside of the 
petiole. However, the upper portion of the intricate mass of 
vascular bundles overlaps the semicircle mentioned on both sides, 
and this has perhaps given rise to the opinion that Dryobalanops 
aromatica forms an exception to the general rule in regard to the 
Structure of the petiole. 
It may here be mentioned that in all essential points the petiole 
of the three species examined by me—lanceolata, aromatica, and 
oblongifolia—has the same structure, at the base as well as below 
the insertion of the blade. 
D. oblongifolia, Dyer, agrees with D. lanceolata, Burck, in 
this, that the lateral leaf-traces separate from the central cylinder 
below the base of the internode. At the base, above the inser- 
tion of the axillary bud, there are, beside the two cortical leaf- 
traces with a duct in each, as correctly observed by Heim, two 
large resin-ducts in the middle of the pith; but these ducts are 
contiguous and are only divided by a narrow bridge. The faet 
is, that the main central resin-duct begins to divide a little 
below the base, at the level of the axillary bud, just as is 
occasionally the case in D. aromatica. The formation of branch 
resin-ducts, higher up the internode, progresses in a manner 
similar to what takes place in D. aromatica, one branch-duct 
entering the apical leaf-trace, which with the two cortical ones 
forms the petiole, while a second enters the axillary bud, and two 
LINN. JOURN.—BOTANY, VOL. XXXI. E 
