IN CEYLON. 
439 
A study of the differences of the species at these two 
tropical places brings forward two important facts. The 
first is that those species which are very dissimilar in their 
foliar periodicities at the two places, undergo defoliation 
in Ceylon during or about the only hot dry season in the 
year. In cases like Bombax malabaricum the leafless period 
coincides, very regularly, with our hot dry and part of our hot 
moist months, and further examples may be cited among our 
introduced species such as Schizolobium excelsum, Hevea 
brasiliensis, Manihot Glaziovii, and many others which 
reserve their leafless period until during the hot dry season 
in Ceylon. In the second place species such as Tectona 
grandis and Terminalia Catappa, which are irregular in foliar 
periodicity at Buitenzorg, are markedly deciduous during 
our hot dry season. 
Ceylon , Buitenzorg , and East Java. 
According to Ursprung the climate at Buitenzorg is 
relatively equable throughout the year, but in East Java 
there is a dry period during part of the year which gives a 
marked periodicity to the climate prevailing there. At 
Buitenzorg, in the absence of marked climatic periodicities, 
the development of plant life is rarely periodic, and what 
does occur is mainly the result of internal rather than 
external forces. Though such is the case, the differences in 
the behaviour of certain species at these two places and in 
Ceylon show distinctly that defoliation is considerably 
influenced by climatic changes. 
At Buitenzorg, trees of -Tectona grandis, A., are never 
leafless at the crown, but in East Java they become 
absolutely leafless. In most parts of Ceylon the tree be¬ 
comes quite leafless during the hot season. 
Trees of Poinciana regia, Boj., are never leafless in 
Buitenzorg, though they pass through a leafless phase in 
East Java. At Peradeniya young trees become leafless, but 
old trees rarely pass through a leafless phase though they 
undergo an annual change of leaf. 
