212 



CHEMICAL AGENTS AND GROWTH 



100 1- 



80 



C9 



60t^ 



iij 



"=> 40 



o 

 o 



^ 20 



o6 



10' 



Fig. 



10 10 10 



CONCENTRATION (moles/liter) 

 4. Response curves of the hypocotyl hook showing the effect of 



cobalt in the dark and with exposure to 0.1 /.(.w/cm- red irradiance (625- 

 700m/x). Dashed line is the difference curve between cobalt in the dark 

 and cobalt in the red, indicating the additive nature of cobalt to the red 

 reaction. 



the FMN curve values, a difference curve is obtained. This curve is 

 almost identical with the difference curve between lAA and lAA + 

 FMN (Figs. 5 and 6), indicating that FMN produces the same re- 

 sponse on the hook opening, regardless of the presence or the absence 



IRRADIANCE. BLUE 



100 

 (mj/cm^) 



1000 



Fig. 5. Response curves of the hypocotyl hook to blue irradiances with 

 water, FMN (lO-^M), lAA (IQ-^M), and FMN + lAA. 



