334 SMITH : APPLICATION OF THE TllEiiHV OK 



taking place, or, in other words, the temperature is limiting. 

 There may be some risk in comparing the results with even 

 the same Bpeciasat places so wide apart and under conditions 

 so different : I have, however, compared the growth of culms 

 which are in the same or nearly the same stage, and I think the 

 broad general fact that the growth at the three places is pro- 

 portional to the temperature when moisture is in excess is too 

 important to bo ignored in considering the applicability of 

 our theory. 



5. Day and Night Growth at the three placed. 

 It will be seen, too, that our theory provides an explanation 

 for another of our general conclusions, namely, that at Hakgala 

 the growth during the day not infrequently exceeds the growth 

 during the night. 



The uniformly high temperature at Peradeniya and Anu- 

 radhapura allows of growth at a very rapid rate during the 

 night, audit is improbable that any day should be found in 

 which the conditions of water supply are so favourable as to 

 allow of an equal or greater growth by day, since days of 

 continuous high humidity are rare and, as has been remarked 

 previously, the light effect on the stomata is always present. 

 If now. however, the growth during the night were limited 

 by the temperature to a much slower rate than occurs at 

 Peradeniya it would obviously be more probable that days 

 should be found on which the conditions would allow of the 

 nighl growth-rate being exceeded. 



\t Peradeniya a day of continuous rain would be the only 

 occasion on which the growl h pel day would be likely to exceed 

 the rapid growth ai night, and even then wo could not expect 

 rnaoh excess because in the rainy weather of the south-west' 

 monsoon the - temperature is litt lc. if any , higher during (he day 



t han during the night. At Hakgala, however, where the growth 



during the nighl is kept quite low by the low temperature) 



• lay of intermittent rain and sunshine inighl cause a growth 



exceeding that of the following or previous night. The growth 



during the hours of rain at the high day temperature might 



