FLl^OKESCENCE YIELD OF CHLOROPHYLL 117 



in the presence of poisons, the fluorescence intensity was increased and 

 the })ends tended to disappear. A more complete presentation of these 

 experiments will be made at a later time. The theoretical conclusions 

 are incorporated in Dr. I'ranck's paper on the "Photochemical Part 

 of Photosynthesis" (seepage 142). 



Discussion 



Lumry : I should like to mention some of our preliminary^ results. We have been 

 trying to find out if the fluorescence yield approaches zero as the light intensity ap- 

 proaches zero. Our measurements suggest that the yield changes with light in- 

 tensity at much lower intensities than has been previously thought. 



