309 



Jack Myers 



but with lowered efficiency, then a description would fall some- 

 where between the two models. The two models have quite differ- 

 ent consequences in restrictions which they require in terms of 

 composition of the two pigment systems, quantum yield, and the na- 

 ture of enhancement. 



From the simple hypothesis on the nature of enhancement there 

 can be derived the relations shown in Table 1 for each of the 

 models. In relating values of E, a, and n to quantum yield we use 

 0(3^ to denote the relative quantum yield (0/0inax^ ^^ affected by 

 quanta distribution. Values for 0^3^ and E, derived independently 

 in terms of a and n for each of the models, permit evaluation of 

 0(i in terms of Ei or Eg and n. The analysis presented is only an 

 extension of that of Bannister and Vrooman-"- but with some change 

 in conventions. 



In search for choice between the two models we have attempted 

 various analyses of enhancement data for comparison with pigment 

 absorption or quantiim yield data. Partly because of uncertainty 

 in the value of n, we have not found any test which leads to an 

 unequivocal answer. I shall cite one such test with respect to 

 quantum yield in Chlorella. Plotted in Fig. 5 are values of rela- 

 tive quantum yield vs. wavelength. Curve EL presents the data of 

 Emerson and Lewis. ^ The other curves are for 0. calculated as in 

 the last column of Table 1 from the Ei and Eg enhancement values 

 of Fig. 2. Curve S describes predictions from the spillover 

 model. Curves P describe predictions from the separate package 

 model for values of n = 1 (Pi) and n = 2 (Pg). The spillover 

 model predicts constant and maximum quantum yield across. the >^2 

 region to 685 mjJ.. The separate package model predicts a maximum 

 quantum yield at only one wavelength, the crossover point 685 m^i 

 where Ei and E2 approach iinity. We ignore the region below 

 560 m|J. because of uncertainties due to carotenoid absorption. The 

 experimental curve beyond 570 mM. is flat except for a 4fo dip at 

 650-660 mu. The separate package model requires a much greater 

 dip for any reasonable value of n. There is no uncertainty that 

 the separate package model requires a less than maximum quantum 

 yield whenever E > 1. There is uncertainty whether the data of 

 Emerson and Lewis have sufficient precision to discriminate be- 

 tween the two models. 



THE KOK EFFECT 



Since enhancement in monochromatic beams has been studied only 

 at relatively low light intensities there has been a recognized 



