471 



S. S. Brody and M. Brody 



from Fig. l6 is used: 



~' -1 ' 



V „= 14, 566 cm (\ 



F, 2 



= 13, 947 cm 



-1 



{\ ^ = 717 mil) and 

 F, 2 



687 m|jL), so that A = 2( v 



V 



F, 2 



) = 1218. The 



F ""'' . • F --■ -'-" • F ,___ 



effective value of % (calculated from Eq. 3) as a function of 'v p^ j^ is shown 

 in Fig. 17. The longest wavelength for the emission maximum in our exper- 

 iments is \'' ,= 732 mu ( "v'' .= 1 3, 661 crn'l ) which yields % =3.77. 

 F, N r , IN 



40 60 



HOURS IN LIGHT 



EFFECTIVE SIZE OF CHLOROPHYLL AGGREGATE 



Fig. 16 Data for Euglena at 77°K; 

 long wavelength emission maximum 

 as a function of age of cells - excited 

 at 436 m^i. 



Fig. 17 The position of the long 

 wavelength emission maximum (at 

 77°K) as a function of the size of the 

 aggregate (based on data obtained 

 from Euglena) . 



The long wavelength absorption maxima of the various aggregates can be 

 calculate^ from their emission maxima, using the previously defined express- 

 ion 6 ^'v A "~'f " 14,793 - 14, 566 = 237 cm"^. Representative absorption 

 maxima calculated in this way are listed in Table II. 



Table II 



Emission Maximum 



% 



Absorption Maximum 



-1 

 V (cm ) X (m(i) 



1 

 2 

 3.77 



The long wavelength shift of emission maximum which occurs during green- 

 ing in Euglena , is accompanied by a broadening of the red absorption band 

 as well as a long wavelength shift of the absorption maximum. 



The spectral transformations in Euglena can be interpreted in several ways: 

 1) there is an association of chlorophyll with different proteins 2) there is 

 an aggregation of chlorophyll molecules 3) both phenomena may occur 

 simultaneously. Whereas chlorophyll molecules are probably bound to the 

 protein portion of the lamellae, we believe that it is primarily the inter- 



