432 WRIGHT: FOLIAR PERIODICITY 
If the reduction in transpiration is really of vital import¬ 
ance or even an appreciable advantage to the plant, one 
would expect to find some semblance to order and regu¬ 
larity, particularly in the period during which the plants 
are leafless and the time of production of young tender 
foliage. 
Holtermann proved that transpiration was greater from 
young leaves than from old ones, and greater during the 
hot dry period at Peradeniya than during other parts of the 
year. Yet there are many trees, e.g., Albizzia procera, with 
tender thin foliage which retain all their leaves during the 
period when transpiration is at the maximum ; and, on the 
other hand, trees such as species of Ficus,with tough leathery 
leaves coated with a thick cuticle and therefore probably 
losing less by transpiration, become leafless. If, however, 
species such as Bombax malabaricum or Cratseva Roxburghii 
be considered, the reduction in transpiration will be found 
to be very great. The Bombax trees remain leafless for 32 to 
96 days during our hottest and driest period, and usually 
produce new leaf at the end of the drought. One tree of 
Cratseva Roxburghii has been observed to be leafless for 
31 to 76 days each year, and this specimen never regains full 
PhZ 1, " April - Bat when each as 
md ' Cna ’ Careya arborea ’ FionB Tsjakela, Star- 
cu ia a ang as, Termmalia belerica, Chickrassia tabularis, 
and many others are studied it ia aeon that thongh they 
become leafleaa doling the hot montha for one or two 
dnya or week, they alwaya prodnce their complete 
prevailing^ while the hot <*7 season is 
For these reasons one mnst assome that checking trans 
puation ia only a consideration to certain species, and thai 
others may, by passing through their foliar stage, like those 
lMt mentioned, actually lead to an increase in transpiration 
^ mmimUm qUanti ‘ y ° fwater * 
