PHYSIOLOGICAL STUDIES 



51 



A and B are unknown substances presumed to exist in the 

 plant cell. The first process is that which determines the rela- 

 tionship between rate of photosynthesis and concentration of 

 carbon dioxide at high light intensities. It is presumed to be 

 a dark process. The second process is that which determines 

 the relationship between rate of photosynthesis and light in- 



O 

 O 



o 



^^28-9X. 



22-5 C. 



/6-3 C. 



Light intensity 



FIG. 4.5. The relationship between rate of photosynthesis and in- 

 tensity of illumination at different temperatures in Chlorella. 

 (After Wassinkei a/.) Highest Light = 1-75 10^ ergs/cm. Vsec. 



tensity when the concentration of carbon dioxide is high. 

 This formulation assumes that the rate of these two processes 

 can vary independently so that the rate of the over-all process 

 may be determined by either. The products of photosyn- 

 thesis are presumed to result from reaction between the 

 carbon dioxide complex and the photochemical product; 

 this is also assumed to be a dark process. A mechanism of 



