322 SMITH : M'PI.H \ HON OF THK THKOI5Y OF 



That the supplj of water necessary for such rapid growth 

 oaa be maintained daring an almost rainless period is no doubt 

 due to the fact that the olump was on low-lying, rather swampy 

 ground in the vicinity of several Large tanks where abundant 

 water is always found close under the surface of the soil. 



The correspondence between growth during the day and 

 rainfall which is observed at Peradeniya and Eakgala is no 

 doubt due to the hut that a rainy day is one in which the 

 humidity is high and transpiration from the adull culms very 

 -mall, but the observations at Anuradhapura show that the 

 true controlling factor in the growth of the culms is the humi- 

 dity of the atmosphere and not . except indirectly, the rainfall. 



2. Growth and Temperature. 



Taking the records of 2-hourly growth at the three places 

 there is a clear general correspondence between the rate of 

 growth and the shade temperature recorded. 



The maximum growth at Hakgala in 2 hours was 2 55 cms. 

 Average temperature 18 '4° C. 



Another case of rapid growth at Hakgala in 2 hours was 

 I'll cms. Average temperature 17*4° C. 



Maximum (average of 5) at Peradeniya in 2 hours was 

 2 - 8 cms. Average temperature 22 - 0° C. 



Maximum (a Bingle culm) at Peradeniya in 2 hours was 

 cms. Average temperature 22 '0° C. 



Maximum (average of 6) at Anuradhapura in 2 hours was 

 3 } cms. Average temperature 25*0° C. 



Maximum (a Bingle culm) at Aniiiadhapuia in 2 hours was 

 to cms. Average tempera tine 2.1 -0° C. 



All these calms were at that stage <>f the Grand Period when 

 the growth fluctuates about a steady value. 



That this rapid growth 18 not continued throughout the 



24 hours at Anuradhapura, bo that tin- growth per day is in 

 mopt -mallei at Anuradhapura than a1 Peradeniya, is due 



to the \i numbei of the hours during which humidity is 



high at iVrudeniyu, bo that rapid growth takes place for a 



