49 NOTES ON DI 'TEROCARPS, 



through that part of the petiole which is a pulvinus, the scleren- 

 chyma is wanting, while the ring of bundles is a little irregular 

 and the cortex is thicker. Such changes are of course connected 

 with the mobility required of the pulvinus: they take place in the 

 petioles of the whorl in the same way as in the fifth leaf. And 

 there is nothing further peculiar about these whorled leaves beyond 

 the circumstances of their association and their inequality. 



Compared with the adult leaves, they are of course much 

 smaller, up to 8.2 cm. long by 4.1 cm. wide, and the vascular ele- 

 ments in the petiole, etc., in the large leaves are altered by the in- 

 creased number of groups of larger xylem vessels in the ring, and 

 by the space within this ring being completely occupied by a com- 

 plex of bundles with much sclerenchyma. At the pulvinus the 

 sclerenchyma is interrupted, and the ring somewhat irregularly 

 broken up. But beyond the pulvinus, in the midrib of the leaf, the 

 included bundles form up into orderly lines in eoncent/ic semi- 

 circles, which get less in numbers of their parts until near the tip 

 of the leaf a condition is reached closely resembling the condition 

 found in the petiole of the seedling leaves. 



Brandis (in Journ. Linn. Soc. Bot. xxxi, 1895, p. 20) suggest- 

 ed sectioning the pulvinus for the study of generic characters; but 

 the middle of the petiole promises more. 



Jour. Straits Branch 



