284 SMITH : 



January to March. He interprets this as an adaptation to 

 check transpiration, and there is evidence that for certain 

 species this is probably the case. He notes, however, certain 

 exceptions which make it impossible to draw the general con- 

 clusion at all rigidly, and it is significant that these exceptions 

 agree very closely with the results of the present paper, and, 

 in fact, extend its scope to deciduous species. The following 

 extracts from Wright's paper show this : — He states on p. 452, 

 " Holtermann (12) 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., Alhizzia 'procera, with thin tender 

 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." 



After mentioning Bomhax malabaricum and Gratceva Rox- 

 burghii which remain leafless during the whole of the dry 

 period and therefore avoid transpiration, he goes on to say : 

 ' ' But when species , such as Phyllanthus indicus , Carey a arbor ea , 

 Ficus Tsjakela, Sterculia Balanghas, Terminalia belerica, 

 Chickrassia tabularis, and many others, are studied, it is seen 

 that though they become leafless during the hot months for 

 one or two days or weeks, they always produce their complete 

 outfit of new tender foliage while the hot dry season is prevailing. 



" For these reasons one must assume that checking tran- 

 spiration is only a consideration to certain species, and that 

 others may, by passing through their foliar stages, like those 

 last mentioned, actually lead to an increase of transpiration at a 

 time when the minimum quantity of water is available in the soil." 



The case of these latter species, which, according to Wright 

 are numerous, is closely comparable to the case of the ever- 

 green species studied in the present paper. They too, by 

 putting on their new outfit of tender leaves at the dry period 

 of the year, lead to an increase of transpiration at that time. 

 There is not much doubt that one explanation will apply to 

 both cases. The evidence of the present paper, though not 

 complete, is, as far as it goes, fairly decisive and, strengthened 



