444 
WRIGHT : FOLIAR PERIODICITY 
species of particular note are Anogeissus latifolia, Bridelia 
retusa, Careya arborea, and Ficus Tsjakela. 
One tree of Anogeissus latifolia was leafless during 1902 
from the 10th to 12th March ; in 1903 from 24th March 
to 6th April, and in 1904 the tree was never absolutely leaf¬ 
less. 
A tree of Bridelia retusa was leafless during 1902 from the 
12th to 24th March, and in 1903 from 24th March to 7th 
April. 
Similarly a specimen of Careya arborea was leafless during 
1902 from 15th February to 15th March ; from 12th to 24th 
March, 1903 ; and in 1904 from 7th February to 8th March. 
Again, a tree of Ficus Tsjakela was leafless from 12th to 
20th February in 1902 ; from 6th February to 1st March, 1903 ; 
and from 18th February to 16th March in 1904. 
In three out of four cases the leafless period was delayed 
in 1903, compared with 1902 ; in one case for 1904 the periodi¬ 
city was delayed, and in another defoliation was earlier in 
1904 than in 1902 and 1903. 
Similar.differences have been noticed for individual trees 
of other species, as for instance Gmelina arborea and 
Berrya Ammonilla, common to Ceylon. India, and the Malay 
Archipelago. 
The date at which leaf-fall commences is very variable 
and is not of much importance. The actual length of time 
during which the tree is leafless is of much more importance. 
The variation in time, of the foliar periodicities of 
species like Spondias mangifera, Bombax malabaricum, 
Eriodendron anfractuosum, Bridelia retusa, or Lagerstrœ- 
mia flos-reginæ, is usually greater than the variation 
exhibited by an individual tree during successive years* 
For instance, the foliar periodicity of different trees of 
Bombax malabaricum may in the same district vary by one 
or two months in the same year, but an individual tree 
during 1900 to 1905 does not vary in its periods of leaf 
activity by more than a few days or a few weeks at the 
most. In many of the cases under observation the trees were 
