340 O. WARBURG Ct ul., S. B. HENDRICKS VOL. 4 (1950) 



virtually as good yields from the red light, whether the base line were darkness or the 

 white light. 



Another limiting feature of the earlier yield experiments was the short duration 

 of not only the periods of illumination (lo minutes) but also the total length of the 

 experiment (commonly less than one hour). By the use of white light we have now 

 succeeded in extending the duration of the manometric yield experiments up to at least 

 10 hours, if not indefinitely. The effects of this important advance are several. In general, 

 the yields may now be determined under nearly the same conditions as obtain during 

 the growth and cultivation of the cells, since the light intensity, temperature, medium, 

 and gas phase during the growth and manometry are essentially the same, and further- 

 more we have found that the shaking does not change the cells under these conditions. 



VIII. EXAMPLES OF DATA 



Protocols I, 2, and 3 provide examples of the data obtained. 



PROTOCOL No. I 



Experiment of V-26-49. 20° C. 630-660 m/t. 5% COg in air. 260 jn\ of cells per vessel. Each 

 vessel alternating 10' in dark and 10' red light; thus when vessel No. 5 was dark, vessel No. 3 was 

 illuminated, and vice versa. 



{Equation 2) 



kc02 k'co2 



Actinometer: — 8.83 f.i\ O^ per minute 



. ^ I 80-8.83 

 Quantum eraciency for Oj, — = =4-7 



1 80-8.83 

 Quantum efficiency for CO,, — = — — = 4.2 



(p 168 — 



. ., . CO, —168 

 Assimilatory quotient, y = = = ^ — i.ii 



02 +151 

 CO 



If y = ^ = — I.II is determined for a given cell suspension, then X02 and XCO2 can be 



obtained by the pressure changes in light and dark in each single vessel. For example, in vessel No. 5, 

 the following figures, taken immediately prior to the readings above, were obtained upon illumination 

 with light of an actinometer value of — 5.07 /il Og per minute: 



Vessel No. 5 



10' dark — 12.5 mm \ 



10' light — 2.5 ,, > 10' H' = + IO-2 mm ^ 



10' dark — 13.0 ,, ) I / tt/ , 



, T , . [ I 20 H = + 20.2 mm 



10 light 1-5 ,, I / TTr , 



/ 1 , } 10 H = + 10. o ,, / 



10 dark — 10. o ,, ) 



References p. 346. 



