LIGHT CURVES OF FLUORESCENCE 



1055 



<u 



1.4 

 1.2 

 1.0 

 0.8 

 0.6 

 0.4 

 0.2 

 



0.2 0.4 6 0.8 1.0 1.2 

 THIOSULFATE CONCENTRATION,?; 



Fig. 28.34. Fluorescence transition point I^ 

 as function of thiosulfate concentration (after 

 Wassink et al. 1942) (cf. fig. 28.27 for meaning 

 of /.). 



2 3 



INCIDENT INTENSITY, erg/cm.^ sec. 



Fig. 28.35. Influence of excess reductants on 

 intensity of fluorescence in absence of CO2 (after 

 Wassink et al. 1942). pH 6.3, 29 ° C. 



(c) Effect of Temperature 



Kautsky and Spohn (1934) noticed that the fluorescence of leaves was 

 stronger at than at 30° G. ; but Wassink, Vermeulen, Reman and Katz 

 (1938) found no such effect on the light curves of fluorescence in Chlorella 

 suspensions (10-30°) {cf. fig. 28.36 on page 1056). 



Franck, French and Puck (1941) found that a sudden cooHng of Hij- 

 drangea leaves from 23 to 0° C. produced a "burst" of fluorescence, which 

 subsided after 10 or 20 minutes {cf. fig. 28.37). We will return to this ob- 



