1942 



KINETICS OF PHOTOSYNTHESIS 



CHAP. 37d 



throughout the experiment should not be much affected by the relatively 

 small increment in average illumination during the "bright" periods. 



An interesting innovation (cf. fig. 37D.24) was the use of a reaction 

 vessel (20 ml.) enclosed, from all sides but one, in a larger vessel (120 ml.) 

 containing an actinometric solution (chlorophyllide, or pheophorbide, and 



liSHSSTe 



Fig. 37D.25. Pressure changes in two manometric vessels with Chlorella (after 

 Warburg and Geleick 1951): (a) small vessel, (b) large vessel. Dotted lines, 

 unmeasured background light, X 436 niu; solid lines, same plus intermittent green 

 light, X 546 m^i. 21% absorption, 0.9 jueinstein/rain. Calculated quantum re- 

 quirements for successive hour periods : 1/7 = 5.1; 5.2; 3.2; 3.3; 3.5; photosyn- 

 thetic quotient, 1/Qp = 1.2, 1.10, 1.28, 1.01, 1.18. Abscissa, hours. Ordinate, 

 pressure change in milUmeters. 



thiourea in pyridine, cf. p. 839). This permits measurement of the light 

 absorption in the reaction vessel, and thus determination of quantum 

 yields of incompletely absorbing suspensions. 



A new precaution was recommended in the preparation of cell suspen- 

 sions — gentle centrifugation ; it was suggested that too densely packed 

 cells can be damaged mechanically during resuspension. It was reported 



