;{(Mi SMITH : APPLICATION OF THE THBOBV OF 



[.—OBJECT OF THE RESEARCH. 



The measurements and observations recorded in this paper 

 wire carried out in Ceylon from January to July, 1906. 



The object of the research was to test the applicability to 

 facts of growth of the Theory of Limiting Factors outlined by 

 F. F. Blackmail in his paper on "Optima and Limiting Factors'" 



(2). 



Theory of Limiting Factors. 

 In this paper Blackmail suggests that out of the physical 

 factors conditioning any of the physiological processes of plant- 

 life, there is as a rule one which at any one time limits the speed 

 of the process. In assimilation he has shown that, given a 

 sufficient supply of light, the rate of the process is limited by 

 the supply of C0 2 available. If the CO., supply is also in 

 excess, the rate of assimilation is Limited by the temperature. 



a 

 o 



£ 



a 



- 



o 



o .- 

 b/- 



7 



T) 



\ 



00 j Supplied 



The above is a diagram typical of the results usually ob- 



Uiined ill assimilation. The curve ( ).\l) represents the relation 

 between assimilation and C0 a supply at a given temperature. 



The part < >.\ represents Increase of assimilation in proportion 

 to in- rea • "t I a supply. After the point A is reached no 



further inn I assimilation is ..In .nurd. This is due to 



the insufficiency of light energy for greater assimilation. The 



1 1 \ repre ente ;i stage in whioh the light is in excess and 



the assimilation ie limited by and increases with the supplj 



of C0 8 The line AD, on the other band, represents a stage in 



