465 



S. S. Brody and M. Brody 



405 436 and 545 mfj. are relatively similar (although some small differences 

 can be noted), but the fluorescence spectra obtained with older Euglena are 

 markedly different - see Fig. 6 for 1^ day old cells and Fig. 7 for 1 week 

 old cells. These data suggest that there are at least two different species 



EUGLENA GRAC.(Z) 



IjOATS 



— 546ni^ 



— 405 m0 



— 4 36m» 



650 700 750 



WAVELENGTH, m^ 



650 700 750 800 



WAVELENGTH, m^ 



Fig. 6 Fluorescence spectra of 1 1/2 

 day old cells excited with wavelengths 

 given above; excitation at roonn tem- 

 perature. 



Fig. 7 Fluorescence spectra of 1 

 week old cells excited with wave- 

 lengths given above; excitation at 

 room temperature. 



of chlorophyll in Euglena which have different absorption spectra and which 

 give rise to the 685 and 7Z0 m|jL emission bands. 



Goedheer (31 ) in his study of greening bean leaves, has noted (with respect 

 to the room temperature spectrum of a fully green leaf, and on the basis of 

 induction phenomena) that the fluorescence around 720 mfj. must be partially 

 ascribed to emission by another form of chlorophyll rather than to scattering 

 and re -absorption in the major peak. 



The experiments described up to this point were made at room temperature, 

 the following experiments involve also measurements at low temperature 

 (770K). 



In Figs. 8, 9 and 10 may be seen a series of fluorescence spectra obtained 

 with Ochrom'onas danica , age 2, 4 and 10 days, respectively. Except for the 

 usual carotenoids, this alga contains no pigments other than chlorophyll a. 

 The fluorescence in the blue-green region will be described in a separate 

 section, below. First we turn our attention to the red region of the spectrum. 

 In the curves obtained at 293°K, there is a small shift in fluorescence 

 maximum with age, from about 690 mjj. to 692 my., and an increase in 

 fluorescence intensity (or relative fluorescence yield). The outstanding 

 feature of the curves obtained at 77°K is the presence of two separate and 

 distinct fluorescence bands in the red region. In the 10 day cells, the band 



