1092 



THE LIGHT FACTOR. II. QUANTUM YIELD 



CHAP. 29 



intermediates of dark metabolism, rather than of carbon dioxide, and thus 

 require less energy. This caused them to inquire into the value of the 

 photosynthetic quotient in the first minutes of illumination. It was in this 



£ 



e 



< 



X 

 CJ 



LU 



a: 



CO 

 CO 

 LU 

 (T 



a. 



I- 

 < 

 re 



10 20 30 40 50 



70 



90 110 



TIME, min. 



130 



150 



170 



190 



Fig. 29.3A. Rates of pressure change during alternating periods of light and 

 darkness, for the same quantity of cells, in two vessels (after Emerson and Lewis 

 1941). Vessels differ in gas volume, thus permitting separate calculation of [O2] 

 and [CO2] (cf. fig. 25.3B and 29.4A). 



t 



UJ 



o 



< 



X 



o 



X 



LlI 



<n 

 o 



o 



< 

 a: 



70 



90 110 



TIME, mm. 



70 



190 



Fig. 29.3B. Rate of exchange of O2 (solid curve) and CO2 (broken curve) calcu- 

 lated from the rates of pressure change shown in fig. 29. 3A for two different vessels 

 (after Emerson and Lewis 1941). 



