Induction Phenomena in Photosynthetic Algae at 

 Low Partial Pressures of Oxygen 



C. p. WHITTINGHAM, Botany Department, Cambridge University, Cam- 

 bridge, England 



An electrochemical method ("Hersch" meter) has been used to 

 determine the time course of oxygen production in photosynthesis 

 for partial pressures of oxygen between 10~^ and 10~^ mm. Hg. 

 Oxygen is adsorbed at the silver cathode forming hydroxyl ions in 



z 



UJ 



> 



X 



O 

 u. 

 O 



UJ 



a 



Ul 



a 

 a. 



< - 



8 9 lO II 12 13 14 15 16 17 18 19 20 

 TIME IN MINUTES 



Fig. 1 . The time course for ox\gen production by Chlorella with ( X ) and with- 

 out (•) 1.2 10~* M p-chloromercuribenzoate. The graph shows the initial burst 

 (considerably lengthened by the slow response sj-stem used here) which is de- 

 pressed by the inhibitor. 



solution; these oxidize the lead of the anode, causing a current to 

 flow when the electrodes are connected by a suitable resistor. Meas- 

 urements were made with Chlorella pyrenoidosa and Scenedesnms 



409 



