490 



W. D. Bonner, jr. 



Figures 5 to 9 show low temperature difference spectra of 'mitodiondrial' 

 suspensions derived from various sources. These sources include cauliflower 

 buds, etiolated black valentine bean and mung bean hypocotyls, cabbage and 



SKUNK CABBAGE 



Abffjrbaiicy 



Ox- DPNH/CN" 



Ox -DPNH/HOONO 



I M M I I I I 



490 520 550 



580 



Wovelength (mp) 



Fig. 9. Diflference spectra (at — 190°C) obtained from skunk cabbage spadix 

 mitochondria. The spectra represent the difference in absorption between aerobic 

 mitochondrial suspensions and suspensions treated as indicated on each curve. 



skunk cabbage flowers. All of these preparations show the same character- 

 istic behaviour with HOQNO or Antimycin A and to reduction by DPNH 

 in the presence of cyanide. 



Reference to the figures showing the low temperature spectra of the various 

 plant preparations shows that there is much more dithionite-reducible 

 cytochrome 'Z)' than can be found following substrate reduction, even with 

 anaerobiosis. This behaviour of the 7/ components is also characteristic of 

 all plant tissues that have been investigated ; so far any reasonable explana- 

 tion of this phenomenon has evaded us. An indication of the magnitude of 



