248 



CHAP. XXVI. THE PHYSIOLOGICAL SCALE 



of the curve are found to be a constant and practically the 

 same as those obtained by the differential method. 



The law of photosynthesis under variation of C0 2 -concentra- 

 tion is that the ratio of activity to the concentration is a constant. 



This is symbolically expressed as — 



-p is a constant. 



The Law of Photosynthesis under Variation 

 of Intensity of Light 



The curve given in fig. 59 relates to Specimen I. (p. 36), 





& too 



to 20 2.0 



Intensity in wo Lux 



Fig. 59. Photosynthetic Curve under Variation of Intensity of 



Light 



of which the physiological zero is at • 13 (13 lux) ; this has to 

 be subtracted from the intensity of light on the ordinary 



