312 SMITH : Airi.H \TJi»\ I u I'll E THEORY OF 



In a set ct readings at Peradeniya on September 1 to 2 

 the air temperature reached 29*0° C. (84-2° F.),and through the 

 kindness of .Mr. H. M. Leake. Government Botanist. Saharan- 

 pur. India. I obtained some readings in which the air tempera - 

 bure reached 31 1° C. (88° F.). In both these sets of obser- 

 vations the close relation between growth and temperature was 

 obvious so t hat 1 he total observations show that throughout a 

 range of from 9-<> C to 31-1° C. (49-2° to 88° F.) the growth of the 

 flowering shoot of different species of Agave and Furcraea cor- 

 responds with the temperature of the surrounding atmosphere. 

 Headings taken at Anuradhapura in the dry region of Ceylon. 

 w here the temperature reached 30'7 C 0. (87'3° F.), were unfor- 

 tunately spoilt by the splitting of the shoot lengthwise early 

 in the course of the experiments, and I omit them. 



Leaving a fuller discussion till a later part of the paper. 

 it may here be pointed out that the influence of light or the 

 humidity of the atmosphere cannot be traced in any of the 

 result- obtained. Some of the records were taken on days 

 of bright sun when the humidity of the atmosphere was quite 

 low. but no diminution of growth from either cause was ever 

 observed, in fact it was just at the periods of brightest 

 sunshine that the most rapid growth was recorded. 



Except for the readings of June 10 to II at Randy I have 

 full records of the temperature recorded by dry and wet bulb 

 thermometers from whioh the humidity can be calculated, but 

 in the absence of any correspondence between humidity and 

 growth these records have not been included in this paper. 

 The water supply seems to have been in excess throughout. 



Internal Temperatun <>j ih< Growing Organ. 



Th'- rapidity of growth when the si t was exposed to bright 



sun was often greater than would be expected from the tern- 



•ure readings. The curves for March 9th at Hakgala and 

 rune I hii at kandv -how that when the shoot is exposed 



to bi imlight the growth increases very rapidly and the 



cum more iharply than the ourv* of temperature. 



