IN CEYLON. 
461 
The effect of Light. 
Wiesner worked with several plants in Europe and 
showed that transpiration decreased with a diminution in 
the intensity of light, and that the reduction of the latter 
as autumn advanced exercised an indirect influence on the 
leaf-fall. 
It has often been observed that the completeness of de¬ 
foliation of individual trees belonging to the same species at 
Peradeniya is variable, and in most cases this variability can 
be associated with the conditions of canopy under which the 
trees are growing. When dealing with the deciduous species 
indigenous to Ceylon, India, and Java, the periodicities of two 
trees (A) and (B) of Schleichera trijuga will he given. The 
two trees of this species growing at Peradeniya are differently 
situated and behave differently in their foliar periodicity. 
Tree A is on open ground and receives light from all 
directions. The trees around it do not rob it of much light. 
Tree B only receives the midday sun and is well protected 
from excessive light in the morning and afternoon. In 
behaviour it differs from tree A in that the defoliation is less 
simultaneous over all parts of the tree and the active foliar 
period is of much, longer duration. These differences may 
be due to the conditions of canopy under which the trees live. 
Many trees of Lagerstroemia flos-reginae,grown in the open, 
drop their old leaves more or less simultaneously over all 
parts of the tree and remain absolutely leafless for one or 
more weeks ; other trees drop their leaves gradually and put 
on a few new leaves before the old ones have fallen. Trees 
belonging to the latter class take a longer period of time to 
effect complete renewal of foliage, and are usually growing 
under conditions of partial shade. 
The same remarks apply to trees of Bridelia retusa, Ficus 
religiosa, and a few introduced species. In all cases the 
existence of dense shade seems to prolong the period of 
defoliation, and in some cases may prevent simultaneous 
leaf-fall from taking place. 
8 ( 9)05 
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