THE ENERGETICS OF PHOTOSYNTHESIS 



43 



Fig. 23. The buluincici- (photograph taken in Prol". Warburg's institute). 



of 50 cm. The inside wall of the sphere is painted in a hght colour and radia- 

 tion is measured with a selenium cell connected to a multiplex galvanometer. 

 More recently, an electron multiplier has been used instead of a selenium cell. 

 This permits the measurement of light absorption accurate to within about 

 3% of the absorption value. The apparatus used by Warburg (27) is depicted 

 in Figure 24 and the interior of the sphere is shown in Figure 25. Light is 

 provided by a 500 watt metal filament lamp. The spectral area required is 

 isolated with the aid of an interference disc. The manometer vessel contain- 



