THE ENERGETICS OF PHOTOSYNTHESIS 



93 



energy of respiration. They are then illuminated with 35 to 60 lA quanta/ 

 min red measured light for 10 min. Within 5 min the O2 capacity appears 

 as a positive pressure. In the next 5 min the steady state of photosynthesis 

 is attained. The much smaller pressure changes have, of course, to be de- 

 ducted from the pressure changes observed during the first 5 min. Thus, the 

 difference between the initial Oo production and the steady O2 production is 

 the Oo capacity. The measurements are carried out with the two-vessel 

 method. 



Numerical example (59): 



Small vessel: Vp = 7.0 ml 

 Large vessel: IV = V.O ml 



A = 8.05 mm- 



Va = 9.88 ml 

 Vg = 14.35 ml 

 B = 10.24 mm2 C = -11.49 mm- 



D = -16.57 mm2 



200 fil cells per vessel. Chlorophyll content: 3.2 mg = 3.56 /xmole = 79.5 /zl. 



Blue-green: /' = 1.2 jul quanta/min. 



Measured light (6440 A): / = 59.8 /xl quanta/min. 



According to equations 17 and 18, 



X02 = +48 ^A (O2 capacity 

 A^coj = — 46 /il 

 7 = -0.96 



O2 capacity _ 48 



chlorophyll content 79.5 



= 0.6 



200 /il cells per vessel. Chlorophyll content: 1.17 mg = 1.305 /xmole = 29.2 /il 



Blue-green: i' = 1.2 yul quanta/min. 



Measured light (6440 A): /i = 37.5 and i-i = 59.5 ^1 quanta/min. 



Small Vessel 



Pressure Changes 



h' 



Large Vessel 



Pressure Changes 



h 



30 min i' only 



2. 5 min i' + i\ 



2. 5 min i' + ix 



5.0 min /' + /i 



30 min /' only 



2 . 5 min i ' + i-i 



2 . 5 min i ' + / 2 



5 . min i ' + i^ 



-10.0 mm 



+ 7.0 mm 

 + 1.0 mm 



— 3.5 mm 



— 56. mm 

 + 10.0 mm 

 + 3.5 mm 

 + 1.5 mm 



— 6.0 mm 



+ 4.0 mm 



+ 0.5 mm 



— 1.5 mm 



— 30 . mm 

 + 5.5 mm 

 + 1.0 mm 

 + 0.5 mm 



