COLLOIDAL AND ADSORBED CHLOROPHYLL 



655 



of supersonic waves. These curves, which can be found in figure 22.15. 

 indicate that enhanced extinction in the far red is characteristic of trans- 

 mission much more than of true absorption— thus supporting Smith's ex- 

 planation and contradicting the results of Noddack and Eichhoff. 



2.0 



(o) Phosphate buffer, AJH 6.6, \/\5M 



ENERGY, e.v. 

 1.5 1.4 



1.3. 



740 



780 820 



WAVE LENGTH, m/i 



T 1 — r — I — I — r-^ 



860 900 940 



{b) Distilled water 



1.6 



I 



ENERGY, e.v. 

 1.5 1.4 



1.3 



740 780 820 860 900 940 

 WAVE LENGTH, m^ 



2.0 



(c) Culture medium No. 231 



1 — I 1 — I — I — r— 



860 900 940 



{.d) \. Cells in distilled water 

 2. Alcoholic extract 



740 



780 820 

 WAVE LENGTH, 'm/i 



— 1 r — I — r 



860 900 940 



820 

 WAVE LENGTH, m/i 



Fig. 21. SOB. Comparative absorption spectra of cell suspensions and pigment ex- 

 tracts of Rhodospirillum rubrum in different media (after Katz and Wassink 1939). 

 Curve 1, cells; curve 2, extract. Concerning the difference between the cell (and the 

 colloidal extract spectra), in A and B, see page 703. 



According to Smith, the molar extinction coefficient of chlorophyll in 

 the maximum of the red band is approximately the same in the aqueous 

 extract containing digitonin and in ether or acetone solution. In other 

 words, the shift in the position of this band from GGO to G75 m^ occurs 

 without a change in its intensity. 



