411 



George Hoch and Olga v. H. Ov/ens 



organism under st 

 relatively high c 

 Chlorella v;as una 

 was inhibited by 

 made the observat 

 only to the coape 



udy. Warburg reported in 1920 that, even in 

 oncentrations of cyanide, respiration of 

 ffected. Photosynthesis on the other hand 

 cyanide but only in strong light. Warburg 

 ion that cyanide inhibited photosynthesis 

 nsation point. In contrast to 'Warburg's 

 n found that a species of Sceneaesmus had 



Chlorella , Gaffro 



a respiration v;hich was not only sensitive to^cyanide but 



which was more sensitive than photosynthesis 



.(6)" 



Figure 2 is an experiment dene with saturating li^'ht in 

 which oxygen uptake, oxygen production, and net oxygen ex- 

 change are shown as functions of time for zero cyanide and 

 10-3m cyanide in Anacystis nidulans . 



8 



TIME IN MINUTES 



1 2 3 4 5 6 7 



TIME IN MINUTES 



In the control sample the typical increase in oxygen up- 

 take occurs at saturating intensities but it is countered 

 by an even larger oxygen production. The result is a posi- 

 tive net gas exchange. Addition of lO'^M cyanide causes a 

 reduction in the rate of oxygen production without a con- 



