ENERGY EFFICIENCY IN PHOTOSYNTHESIS 



285 



Several important investigations have been carried out in 1951 and 

 1952, subsequent to Rabinowitch's book (1951) and to Emerson's 

 researches (Emerson and Nishimura, 1949; Nishimura et al., 1951) on 

 the manometric difficulties. 



60 



80 



40 



TIME, min 

 Fig. 4-1. Changes in the concentration of dissolved oxygen with time in algal-cell 

 suspensions in light and in darkness. The light was turned on at the point indicated 

 by the arrow pointing upward, and off at the point indicated by the arrow pointing 

 downward. The quantum efficiencies, in molecules per photon, are indicated by *. 

 The quantum requirement would be l/*i. V = violet; R = red; G = green; 

 3 = blue. 



Brackett (Olson et al, 1949) has developed a method for measuring 

 dissolved oxygen quickly and accurately, using a special platinum elec- 

 trode and an alternating current. He can determine the concentration 

 of dissolved oxygen in a suspension of algae in less than 10 sec. With 

 this apparatus Brackett (personal communication, 1952)* has carried out 

 a very careful investigation on the time lags in photosynthesis under a 



* Added in proof: Brackett et al., 1953a. 



