:VA(\ vMlTH : APPLICATION ok THE THEORY OF 



able to sustain coming after a period of great activity, it 

 would furnish also some clue to the cases in which the day 

 growth exceeds that of the following night. If the culm is 

 actively growing during the day owing to favourable conditions 

 then a continuance of those conditions during the night would 

 not result in continued rapid growth. Taking two days, one 

 rainy the other dry and sunny, we should expect that the 

 following nights being equally favourable to growth, the 

 growth during the night following the dry day would be greater 

 than the growth following the wet day. 



3es of this sort may perhaps be found in the record of 

 i be measurements at Hakgala, but a careful examination, both 

 of Luck's figures and my own, shows a large number of cases 

 in opposition to this theory, i.e., there is often as rapid a growth 

 at night after a day of rapid growth as after a day of slow 

 growth. Further, the 2-hourly measurements at Peradeniya 

 show that provided the humidity keeps high the falling off of 

 growth to be expected on this theory by a continuance of 

 favourable conditions does not as a matter of fact occur. In 

 fact neither is the theory itself capable of such accurate state- 

 ment, nor is it so fully applicable to our results as the theory 

 of limiting factors outlined abo\ e. 



3. ( 'OMPARISON OF AG A VE AND DENDROCALAMUS. 



Let us now broadly compare the two cases of Agave and 

 Dendrocalamus. Both on our theory come under one general 

 role, namely, that water supply being sufficient or in excess, 

 the growth is limited by the temperature of the growing shoot. 

 In the case of Agave the supply of water seems always to be 

 sufficient, so that the tomporat ore effect is observahle through- 

 out. None of our cases ha9 shown any falling off of growth even 

 in the hottest pari of the day. On the other hand, the water- 

 supply to the young bamboo culms is constantly in defect 

 during the day, and at Peradeniya and Anuradhapura is so 

 during pari of the nighl also, so that the time during which 

 the temperature effeot ran be observed is curtailed to the 



