260 CHAP. XXVII. SIMULTANEOUS VARIATION OF FACTORS 



increase of activity practically throughout the entire range 

 of temperature- variation. The actual curve with light o -4 S 

 for all temperatures is indicated by the dotted line for 

 comparison with that of S. (The curve should have been 

 placed much lower down.) In order to show that the effect 



Fig. 60. Photosynthetic Curves under Variation of Temperature 

 carried through a Cycle at Intensity of Light S (upper curve), 

 and at Intensity 0-48 (dotted curve). The middle curve is 

 obtained by multiplying the activities under 0-4 S by 2-5, 

 which is the ratio of the two intensities S and o • 4 S (see text). 



of light S is 2 • 5 times that of «4 S, the activity for the lower 

 intensity has been multiplied by 2 -5, and the two curves for 

 S and for 0-4 S X 2 • 5 are reproduced, the former in thick 

 and the latter in thin outline (fig. 60). They had to be 

 printed slightly apart from each other, otherwise one would 

 have overlapped the other, which is a remarkable proof that 

 the effect of change in the one factor, light, is unaffected by 



