1404 



INDUCTION PHENOMENA 



CHAP. 33 



about 1 hour. The enhancing effect of anaerobiosis on the "second wave" 

 is shown by figure 33.48. 



The curves obtained by Shiau and Franck in nitrogen and in air, in the 

 presence of cyanide, also were mentioned on page 1402. Effects similar 

 to those of cyanide could be brought about, as usual, by low temperature or 

 by carbon dioxide deprivation. 



> 10 



in N2 



— in N2 



2 3 



INDUCTION TIME, min. 



Fig. 33.48. Anaerobic fluorescence induction curves of Chlorella 

 at 24° C, showing the second wave (after Shiau and Franck 1947). 

 Time in darkness shown on curves. Light intensities are: (a) to 

 (d), 3.0 X lO^erg/cm.^sec; (e)2.2 X lO^erg/cm.^sec. 



Cells affected by long anaerobic incubation (as well as cells from old 

 cultures) were found to be permeable to methylene blue, while young 

 healthy cells were not stained by this dye. This points to cell permeabihty 

 as one variable possibly responsible for variations in the shape of the induc- 

 tion curves. 



The initial intensity of fluorescence of isolated chloroplasis was the same 

 in nitrogen or air; there appears to be no inhibition of their photochemical 

 activity by aerobic or anaerobic dark metabolism. The mechanism of the 

 photochemical inhibition (revealed by the rise of ^ at the beginning of illu- 

 mination) may be the same as in whole cells, but the practical absence of the 

 subsequent decay in light, and its extreme slowness in the dark, indicate the 

 inefficiency of the respiratory mechanism removing the inhibitor (which in 

 this case apparently cannot overcome the continued production of the 

 inhibitor in hght) . 



(g) Oxidants and Neuiralizers 



Related to the efl"ect of oxygen is that of "substitute oxidants," such 

 as quinone or ferric iron compounds. If anaerobic inhibition is due, to a 



