1330 



INDUCTION PHENOMENA 



CHAP. 33 



general significance of the bursts. They cannot be compared with the 

 polarographic data of Blinks and Skow, and of Damaschke, Todt, Burk and 

 Warburg, whose instruments were able to record bursts and gulps lasting 

 only a few seconds, irrespective of their volume. 



The transient gas bursts in light (and the equivalent gulps at the begin- 

 ning of darkness) increase, according to Emerson's observations, with the 

 number of cells in the vessel, and the carbon dioxide concentration, while 

 the steady rate of oxygen liberation or consumption (reached after 5 or 10 



z 



+ 2 





 -I 



+-I 





 -I 



S 9 



^ .8 

 *"/ 7 



c -eh 



! +6 



» 



o. +4 



J 



=1 +2- 



«r 



? 



o 



f -2- 

 "^ -4- 



(A ^ 



O 



8 12 16 20 



TIME IN MINUTES 



24 



Fig. 33. 6D. Example of transient gas exchange phenomena measured 

 with "synchronized" manometric vessels (after Emerson and Chalmers 

 1954). Shows O2 burst and CO2 gulp in first minute, CO2 burst in second to 

 fourth minutes, steady photosynthesis, with Qp — 1 after the sixth minute. 



minutes in light, and only after a considerably longer time in darkness), 

 is much less affected by these factors (more about this in the next section, 

 since these transients have been studied more extensively in carbon dioxide 

 than in oxygen exchange) . 



Van der Veen (1949^--) apphed another rapidly registering method — 

 the measurement of heat conductivity — to the study of induction. In air, 

 or nitrogen, this method is used to determine the exchange of carbon di- 

 oxide independently from that of oxygen (cf. below, section 3); but if a 

 hydrogen atmosphere is used, changes in both oxygen and carbon dioxide 



