CHLOROPHYLL BANDS IN PLANTS 701 



Table 22.IV 

 Absorption Bands in Leaves (after Lxbimenko 1927) 



I II III V VI VII 



Band (o) (fe) (a) IV (0,6) (a,6) (0,6) (6.0) VIII 



Chi {a + h) in 



ether", X . . . . 669- 648- 619- 599- 571- 547- 506- 467- 439- 415— 

 655 638 605 570 559 523 489 446 424 



Leaves, X 



from . . . 700- 660- 630- 600- — 555- 510- 450- — 418-^ 

 680 650 620 570 — 542 490 430 — 



to 680- 648- 620- 595- — 545- 505- — — 430— 



655 638 610 575 — 535 480 — — 



° c/. Table 21.1. 



Photometric curves prove that many of Lubimenko's visually recorded 

 "secondary bands" are only shoulders on the slopes of the main bands or 

 slight ripples on almost uniformly high absorption plateaus (c/., for ex- 

 ample, figs. 22.13 and 22.15). Apparent shifts in the positions of these 

 "maxima," or even the disappearance of some of them, could easily be 

 caused by changes in the ratios of chlorophylls a and h, as well as by varia- 

 tions in scattering. Lubimenko saw in these differences an evidence of 

 variability of chemical composition of "natural chlorophyll" (a name given 

 by him to a hypothetical complex formed by proteins with all the plastid 

 pigments) . 



Albers and Knorr (1937) found that the number and position of the ab- 

 sorption maxima in single chloroplasts of Protococcus, Spircgyra and Zy- 

 gnema vary not only from species to species, but also from specimen to 

 specimen. In addition to the maxima at 681-683 m^ and 672-675 ui/jl, 

 which may be attributed to chlorophylls a and b, respectively, some chloro- 

 plasts showed secondary maxima at 667-669 m^u, 678-679 m/x and — rather 

 unexpectedly — also in the far red, at 698 niju (c/. fig. 22.35). 



Albers and Knorr considered these results as indicating variations in 

 the chemical nature of chlorophyll (e. g., oxidations or reductions) that they 

 thought might be associated with the participation of chlorophyll in photo- 

 synthesis (c/. Vol. I, chapter 19). 



(b) Red Bund of Chlorophyll h 



The main red absoiption Ijund of chlorophyll b is noticeable, according 

 to Lubimenko (1927), in some spectra of leaves (groups 1 and 2, cf. page 

 700) but not in others (groups 3 and 4). There is no doubt that this 

 l)and, too, is shifted toward the red from its position in solution (642.5 

 niju in ether), but the extent of the shift is difficult to measure, because the 

 band appears merely as a hump on the short-wave side of the main chloro- 

 phyll a band. Lubimenko's table (Table 22. IV) gives, for the band axis, 



