SEASONAL VARIATION OF THE C0 2 -COEFFICIENT Iig 



(b) C0 2 -concentrations of 5 mg. and 7 • 5 mg. : 



Activity for 5 mg. = 149-50 

 7-5mg.= 248-46 



K= 248-46 -I49-5Q 58 



7'5 — 5 

 Specimen II. C0 2 -concentrations of 2 -7 mg. and 4-5 mg. : 



Activity for 2 • 7 mg. = 60-5 

 4-5 mg. = I3I-73 



K= i3 i-73-6o- 5 . = 



4'5 -2-7 

 Specimen III. C0 2 -concentrations of 2 -62 mg. and 7 -o mg. : 



Activity for 2 • 62 mg. = 70-07 

 7-00 mg.= 249-57 



= 249 '57 -70-07 = 5 



7-0 — 2-02 



The practical agreement of the coefficients of the different 

 winter-specimens is indeed remarkable. It shows that under 

 similar conditions the physiological constants of different 

 plants are of the same order. I shall in a later chapter 

 explain a different method of obtaining the coefficient from 

 measurements on the physiological scale. 



The following is the formula for the calculation of a 

 photosynthetic activity A c at a higher concentration, from 



the activity A c at a lower concentration : 



A c = A c + K (c - c) 



Seasonal Variation of the C0 2 -Coefficient 



The general physiological depression due to winter 

 persisted till the middle of February, after which the 

 activity increased with the return of spring. By the 

 end of February the photosynthetic activity exhibited a 

 general enhancement. In the winter months no photosyn- 

 thesis occurred at a lower C0 2 -concentration than 2 • 5 mg. ; 



