1856 



SPECTROSCOPY AND FLUORESCENCE OF PIGMENTS CHAP. 37C 



750 m/i, in a culture of "Purpurspirillen" (and of a band at 660-670 m/i in extracts from 

 this culture) points, according to Barer, to a contamination of purple bacteria cultures 

 with green bacteria. 



(d) Phycohilin Spectra in vivo. 



New absorption curves of blue-green and red algae, with the allotment 

 of absorption at selected wave lengths to the several pigments, were given 

 by Duysens (1952); they will be reproduced in section 7 together with the 

 action spectra of fluorescence (figs. 37C.51 and 53). 



(e) Changes in Absorption Spectrum during Photosynthesis 



An old problem is whether chlorophyll (or other cell constituents) 

 undergo a chemical change during photosynthesis that could be detected 



C/ 



03 



02 



RHODOSPIRILLUM RUBRUM 



.«-\ 





g 



I 



(3 



9 B690 \ 



I \ 



■absorption spectrum 



\ 

 I 



\ 



« 



spectrum of the charge 

 "of absorption 

 (enlarged)-.^ 



•< 



&< 



(3 



wave length in mfi 

 __l l_ 



08- 



OC 



002 OM- 



0.01 Q2 



-001 



- OOIS 



-0010 



- 0.005 



-0005 



900 



850 



aoo 



150 



Fig. 37C.35. Absorption spectrum, and spectrum of the reversible change of ab- 

 sorption by irradiation of Rhodospirillum rubriim, in tap water (left); and of colloidal 

 extract from Chroviatimn (right) (after Duysens 1952). The ordinates of solid curves 

 are on a scale ten times (left) or fifty times (right) smaller than those of the dashed curves. 

 Decrease in absorption is plotted upwards, increase downwards. The main absorption 

 maximum of B 890 is indicated by arrow. 



spectroscopically. Of the two previously known phenomena belonging 

 to this field, one — the slow change in transmission of light by photo- 

 synthesizing leaves (p. 680) — has been attributed partly to chloroplast 

 realignment, and partly to scattering by newly formed starch grains. The 



