500 Discussion 



explanation for the discrepancies of cytochromes a^, a, c and the large cytochrome b 

 band of Lundegardh. 



Figure 13 of Bonner's paper (p. 493) shows that treatment of bean roots with CN" 

 and DPNH clearly shows (in a low-temperature difference spectrum) the bands of the 

 cytochrome O3, a, c, b system in the usual proportions (corresponding roughly to one 

 each of the components). The oxidized minus dithionite spectrum, however, clearly 

 shows a great excess of accessory '6' pigments, that completely obscure the b and c 

 bands of the respiratory components. 



This result for bean root suggests that the large amounts of accessory '6' pigments 

 may be a general phenomenon and provide an explanation for Lundegardh's data. In 

 this case we reach the interesting conclusion that the accessory pigment (of 6-type) 

 is best correlated with the anion transport, thereby providing a haemoprotein of the 

 type required by Davies' theory on this topic. 



