387 



Max H. Honimersand 



60 80 

 TIME (mm) 



Fig. 6. Effects of different colors of light in 

 overcoming the induction lag caused by treatment with 

 CCCP. The curves are: •, white light, control; o, 

 same, 3.3 x lO'^M CCCP; a, red light (Corning filter 

 #2030), control; A, same, 3.3 x lO'^M CCCP; ■, blue and 

 far-red light (Corning filter #5031), control; q, same, 

 3.3 X 10-5m CCCP. 



does not inhibit photos3rnthesis in living cells. There is an 

 indication, however, that CCCP may uncouple some of the photosyn- 

 thetic phosphorylation that occurs in-vivo in algae. We have 

 followed the effect of CCCP on the uptake of labeled acetate in 

 Chlamydomonas reinhardtii , a species in which light promotes 

 acetate assimilation several fold above the dark rate. (CCCP 

 causes an induction lag in oxygen evolution in Chlamydomonas the 

 same as in Chlorella .) Acetate uptake was completely inhibited 

 by CCCP in the dark at concentrations below IO'Sm, and the 

 inhibition was not in any degree reversed by light (fig. 7). By 

 comparison, cyanide is much less toxic. 



It is generally held by most investigators that the light 



