LIGHT ABSORPTION BY FIGMENTS in VIVO 



1843 



shift of the al)sorptioii peak, than did hoiUng (fig. 37C.25). In Swiss chard 

 and tobacco leaves, on the other hand, dipping in ether caused an increase 

 in absorption, particularly in the green; this increase was larger than the 

 simultaneous decrease in reflection (fig. 37C.26). Spectra of chloroplast 

 -preparations showed the transition from the spectra of leaves to those of 

 pigment extracts (fig. 37C.27). 



100 



UJ 



o 

 q: 



Q. 



40 



20- 



REFLECTIQN 



FRESH LEAF 



ETHER DIPPED LEAF 



BOILED LEAF 



J I I L 



J L 



J L 



I I 1 L 



400 



500 600 



WAVELENGTH- m mu 



700 



Fig. 37C.25. Absorption and reflection curves of fresh, boiled, and ether- 

 dipped leaves of spinach (after Moss and Loomis 1952). 



Strain (1950) discussed the participation, in the light absorption by 

 photosynthesizing cells and tissues, of noncolored components with a 

 weak general absorption, particularly at the shorter waves (c/. p. 684). 

 He referred to this absorption as "cellular opacity" and suggested that it 

 may account for some of the features of the action spectra of photosynthesis 

 (described in chapter 30), such as the low yield in the far red and in the 

 blue-violet region of the carotenoid absorption. (A weak absorption by 



