233 



1 CHARLES S. YENTSCH 



2 out that photosynthesis is not a direct function of light 



3 intensity. If one doesn't experiment-- 



4 CHAIRMAN STEIN: >fr . Yentsch, remember you 



5 are talking for the record and it is going to be difficult 

 g for any chart you draw on the board to be reproduced in 



,j the record, and I wondered if you would think of your 



g presentation as someone is going to read it in the record. 



9 We don't edit anything out and that may be the trouble. 



10 It will appear verbatim. 



11 MR. YENTSCH: Okay. I will try to explain 



12 it in simple enough fashion so that you won't need a graph. 



13 CHAIRMAN STEIN: Right. 



14 MR. YENTSCH: But I will put it on the 



15 board anyway. 



16 Along the Y axis, if this (indicating) 



17 is photosynthesis, along the X axis If this (indi- 

 Ig eating) is light, increases in light intensity and photo- 



19 synthesis follow a linear pattern up to around 10 or 20 



20 percent of full sunlight. Beyond that point further 



21 increases in light are not elicited as further increases 



22 in photosynthesis. The reason for this is that photo- 



23 synthetic process is largely controlled by enzymatic 



24 processes. At the point where the curve begins to flatten 



25 out it moans that the enzymatic processes are just working 



