certain Tropical Trees . 71 
of Amherstia nobilis wither when in water quicker than the 
green leaves of lifted or partially uplifted branches, shows 
at least that a protection against excessive transpiration is by 
no means superfluous. 
(2) The fact that the young red leaves of this plant 
transpire more rapidly when outspread than when hanging 
vertically, indicates that the hanging habit, whether specially 
adapted to that end or not, affords some measure of 
protection. 
Of the trees which have hanging branches, not a few possess 
brightly coloured young foliage. 
Reference has been repeatedly made to the red tint of the 
young leaves of Amherstia nobilis . Stahl, in addition to this 
instance, mentions the following : One variety of Cynometra 
cauliflora — bright rose-colour ; Jonesia reclinata — golden- 
green to bright red ; Brownea hybrida and Brownea gran- 
diceps — bright red, freckled with green. To these may be 
added Saraca indica — rose-coloured. 
On the other hand, the young leaves borne on hanging 
branches are white in the following : one variety of Cyno- 
metra cauliflora^ Cynometra ramiflora , Humboldtia lateriflora 
(except two small rosy nectaries), Calophyllum bracteatum 1 . 
Although, then, the occurrence of coloured sap is not universal 
among these trees, it seemed nevertheless not unlikely that, 
in those cases in which it occurs, it might serve as a means 
of protection against too strong action, either thermal or 
chemical or both, of the sun’s rays. 
Wiesner 2 has already called attention to the possibility 
of such protection being afforded by coloured saps. Stahl 
makes the not insignificant remark that the leaves of Jonesia 
reclinata are in shade gold-green, in sun bright red 3 . 
A direct change in leaf-colouration was observed by me 
Trimen, Handbook of Flora of Ceylon, Part I, p. 102; Part II, pp. 113, 114. 
2 Loc. cit. 3 Loc. cit., p. 144. 
