TEMPERATURE AND LIGHT 



26l 



change in the other factor, temperature, through a con- 

 siderable range of variation. 



Table XXXVII. — Showing Combined Effects of Partial Factors 

 Temperature and Light. Temperature carried through a 

 Cycle, and Light in Two Stages of 0-4 S and S 



Translocation of the optimum temperature under increased 

 intensity of light. — Before discussing these results I would 

 draw attention to the effect of intensity of light in modifying 

 the optimum temperature already referred to on p. 139. We 

 find in the table that for 0-48 the optimum was at 30 C, 

 the activity being 248-4. A rise of i° C. caused a depression 

 to 232-0. In contrast to this is the effect of the more in- 

 tense light, under which the optimum is raised to 33 C, 

 the activity being 732-0. Further rise of temperature of 

 a single degree produced a fall to 653. 



Detailed consideration of the two characteristic curves. — 

 The two curves, for S and for o -4 S (the latter multiplied 2-5 

 times), are seen to run parallel to each other. The notice- 

 able divergence is after 30 C, the optimum for 0-4 S, after 

 which the curve is reversed, whereas the curve for S con- 

 tinues to rise until the optimum is reached three degrees 



