432 



H. GAFFRON 



a minimum, photosynthesis starts and stops within a second and 

 reaches the steady state a few seconds later (Fig. 6 and Fig. 3 in ref. 

 3). 



The most talked about abnormal induction effect for carbon dioxide 

 is perhaps the one found by Emerson and Lewis (7) in Chlorella: the 

 carbon dioxide gush when the light is turned on. Our version with 

 Chlorella at 15°C. is shown in Fig. 2. The upper curve shows the ac- 

 tual recording, the lower curve the corresponding computed rates. 



o 

 o 







n 



Exp. 50 Chlorella 

 M/500 Bicarb. Temp. 15' 



-I 



5 7 9 



MINUTES 



Fig. 2. Initial carbon dioxide evolution preceding its absorption at start of illu- 

 mination in Chlorella. Strong "Pick-up" when light is turned off. Compare Emerson 

 and Lewis (7, Fig. 4). 



We have no machine to translate the upper into the lower curve. 

 We merely take the tangents at a certain number of points — a simple, 

 inaccurate, yet so far adequate way to see what is going on. In most 

 cases the raw recording of pH changes already reveals the story. 

 Figure 2 should be compared with the idealized drawing in the paper 

 by Emerson and Lewis (7, Fig. 4) based on measurements with algae 

 suspended in an acid medium. Important is the clear break toward a 

 faster uptake of carbon dioxide the moment after darkening. This ex- 

 ample may serve to demonstrate how our apparatus is capable of con- 

 firming faithfully the occurrence of such complex reactions which were 

 found before with more sluggish methods. 



