110 



SPECTROSCOPIC INVESTIGATIONS 



systems. These appear to differ from those of the three bacteria. As 

 regards the latter, Ph. phosphoreu7n certainly deviates much from the 

 others. Although Ph. splendidum and Ph. fischeri have different spec- 

 tra, it is perhaps not advisable to take their difference for granted as 

 we have to account for the absorption of the light by the bacteria 

 themselves. Although this is probably negligible, Ph. fischeri has a 

 distinctly yellow color and in this case the absorption may well be of 

 some importance. This should affect the short-wavelength part of the 

 spectrum in particular. 



580 



460 500 540 



Fig. 9. Emission spectra of three luminescent fungi. 



620 m^ 



Occasionally spectra of bioluminescent processes have been pub- 

 lished. It is difficult to compare them with those just discussed, as it is 

 uncertain and even unlikely that the precautions we have mentioned 

 have been observed during their measurement. For example, two 

 spectra of the emission of Cypridina have come to our knowledge, 

 one by Coblentz (1926), the other by Eymers and van Schouwenburg 

 ( 1937 ) , showing maximum emission at about 480 and 464 nxfi respec- 

 tively. Both spectra have been obtained by moistening Cypridina 

 powder before the slit of the spectrograph. This powder is a strongly 



