422 



Birgit Vennesland 



(2) 



Another set of important experiments has to do with the activated 



CO_ or O^ precursor — also called the "photolyt"'' '. The results of a 

 demonstration experiment, shown to me by Jetschmann in Warburg's Institute 

 in October, 1961, have been graphed in Fig. 1. 



701- 



60 



50 



40 



o 



u 



4. 



30 



20 



A 5 9^1 



27 5 



Ml 



IQ8^I 



31 2^1 



JETSCHMANN 



Fig. 1 The Activated CO_ or 0„ Precursor 



Four Warburg vessels are set up with identical contents: 100 pi of Chlorella 

 cells in culture medium. These vessels are gassed with different gas mix- 

 tures. The first two vessels contain 20% COVair; the third 20% C02/ar- 

 gon, and the fourth, argon. After half an hour of equilibration in the dark, 

 acid fluoride is tipped into the second, third and fourth vessels, but the 

 first vessel is illuminated with a bright light before tipping acid fluoride. 

 The amount of fluoride used is sufficient to inhibit respiration completely. 

 A positive pressure due to release of CO^ appears in every case after fluor- 

 ide addition. The bar graph shows the amounts of CO^ formed when the re- 

 actions have gone to completion. The CO„ released in the fourth vessel is 

 a measure of the amount of glutamate present. This is equivalent to the 

 chlorophyll content of the cells. The CO^ released in the third vessel 

 gives the glutamate plus the CO^ bound as bicarbonate when the cells are 

 in 20% CO^. The CO^ released in the second vessel is greater than that 

 released in The third vessel by an amount equivalent to the glutamate. This 

 is the aerobically bound CO^ or the activated CO^. The first vessel does 



