76 



Swiss Chord Leaf yyK 

 705-635nn/i 



27xl0'*sec' 



T t 



Measuring I Off On 



Light On , '^'^^'"'^ 



Light On 



436 m/i 



h 50sec 



Off 



Figure 8. Measurements of thekinetics of absorbancy change in the region of 

 "P '""in a S\7iss chard leaf frozen at the temperature of 77°IC. In this case, 

 the measuring light (slits 1 mh,) causes appreciable activation of the absorb - 

 ancy change. However, the increase on illumination at k36 xrii is marked. The 

 rate of absorbancy changes is calcxaated per leaf thickness {.k ram). Experi- 

 ment 61-10. 



Splnoch Chloroplotti 



Off 



555-940m/t 



77*K 



T 



loo I./I* 0.001 



! 



Actinic 



Light On \ Y 



eSOmii log I./I*0.004 

 (I) J. 



Mtaa. Light On 

 I" SOiec A 



Figure 9 . A comparison of room and low temperature response of cytochrome f 

 in a suspension of spinach chloroplasts (279 MG chlorophyll a/ml). The ac- 

 tinic light employed in both cases is of the same intensity and a wavelength 

 of 680 np. Tlie appropriate absorbancy scales for the two traces are indi- 

 cated, tlpon illumination, the absorbancy at 555 mp. decreases with respect to 

 that at ^kO riyi. Experiment 57B 56, 57. 



