UNIFORMITY OF EXPERIMENTAL MATERIAL 4S0 



oells removed from the culture. I regret tlwit I am not prepared to draw such cin-ves 

 for you. 



French : If you centrifuge out little cells from big ones from a continuous culture 

 do you get much difference in the growth or photosynthetic rates and chlorophyll 

 content? 



Myers: We have not tried to do that. Professor Tamiya has been doing it. 

 Perhaps he can ans\\er ^our question better than I. 



Tamiya: By centrifugal fractionation they can ho separated t© some extent, 

 but not very sharply. 



French : But are the differences in the cells as great as though they were pro- 

 duced by modifying the culture conditions? 



Tamiya: Maybe so, if we repeat the fractionation many times; but to achieve 

 this we must expect to lose a very large quantity of algal cells. 



Emerson : I have an answer for Professor Wassink. We have measured quantum 

 efficiency of cells in different stages of development. Lewis and I did this by frac- 

 tional centrifugation, and recently we have been doing it by controlling the 

 periodicity of light and darkness during culture growtli. From the evitlence 

 obtained by fractionation of a given batch of cells, the steady-state quantum effi- 

 ciency seems to be about the same for large and small cells, but the transients at 

 the beginning of the light and dark periods may differ greatly at successive stages 

 of development of the cells, and if the transients are included in calculation of 

 quantum yields, then large differences in yield are easily obtainable. 



Wassink: How long do these transient periods of rates of metabolism last? 

 Just seconds or minutes? 



Emerson: According to our evidence from manometric experiments, these 

 transients last for several minutes. 



References 



1. Myers, J., and Clark, L. B., J. Gen. Physiol, 28, 103 (1945). 



2. Novick, A., and Szilard, L., Science, 112, 725 (1950). 



.*}. Tamiya, H., et nl., Biochim. et Binphys. Acta., 12, 2,3 (1953). 

 4. Xihei, T., Sasa, T., Miyachi, S., Suzuki, K., and Tamiya, H., Arch. MikrobioL, 

 21, 156(1954). 



