IN CEYLON. 
449 
lead to any great difference in the transpiration from 
Cyanotis zeylanica, yet other plants which had been trans¬ 
planted into pots transpired more than those cultivated 
under natural conditions, and showed striking changes in the 
anatomy of their roots. He also states that the transpiration 
in moist tropical climates is less significant than that from 
quick-growing plants in the warm and sunny part of an 
European climate. On the other hand at certain hours of a 
clear sunny day in the tropics the transpiration is undoubt¬ 
edly much greater than in Europe. He also points out that 
transpiration in the dry districts of the Northern Province is 
much greater than in the moist warm climate of Peradeniya. 
The actual weight of water lost by large tropical trees 
cannot be determined with ease, and it would not be safe to 
estimate the probable amount from the results of experi¬ 
ments with branches and seedlings of particular species. 
Certainly the amount of water lost from branches of trees can 
be determined, and more or less approximate calculations 
made of the amount likely to be lost by the whole of the 
tree, but the absence of a proper system of roots on such 
cuttings prevents one from using the results with an 
assurance of their general applicability. The experiments 
do, however, suggest that in many of the ordinary arbores¬ 
cent forms growing in the tropics, the transpiration is not 
necessarily greater than in Europe. In all probability the 
transpiration from certain trees at Peradeniya in the moist 
dull months of June and July is less vigorous than in 
Europe during summer—certainly the assimilation processes 
in the leaves are almost at a standstill at Peradeniya during 
that time. The transpiration throughout the year at Buiten- 
zorg, and at Peradeniya from May to December, is apparently 
not much more vigorous than in middle Europe in summer. 
There is therefore no reason to expect that special structures 
should be formed in tropical plants to meet the exigencies 
of transpiration during [the months mentioned, and the 
possession of abundance of foliage in both areas during such 
periods is what one may logically expect to find. But the 
