1844 



SPECTROSCOPY AND FLUORESCENCE OF PIGMENTS CHAP. 37C 



other cell constituents should affect the action spectra most strongly in the 

 regions where absorption by photochemically active pigments is relatively 



small.) 



Krasnovsky and Brin (1948) gave the data listed in table 37C.IIIA 

 (section 5) on the effect of boiling and freezing on the absorption spectrum 



lOQi r-'-T 1 1 1 1 r~-i 1 1 I I r r 



I I 



■BOILED LEAF ■ 



ETHER DIPPED LEAF 



I I I I I I I U 



400 



500 600 



WAVELENGTH- m mj 



700 



Fig. 37C.26. Absorption and reflection curves of fresh, boiled, water-infiltrated 

 and ether-dipped leaves of tobacco (after Moss and Looniis 1952). 



of leaves. Boiling shifts the red band to its position in solutions while 

 freezing in liquid air leaves it unchanged. 



Barer (1953) minimized scattering, in measuring the absorption spectra 

 of cells, by suspending them in a protein solution with an index of re- 

 fraction adjusted, by means of a phase contrast microscope, to match that 

 of the cell material (Barer, Ross and Tkaczyk 1953). Fig. 37C.28 illus- 

 trates the success obtained with a suspension of purple bacteria; the 



