C. J. p. SPRUIT AND A. SPRUIT-VAN DER BURG 



109 



In making spectral energy measurements by the photographic 

 method, one should always take averages of a considerable number 

 of separate exposures, as the plates are never quite homogeneous. 

 Other points to be observed in the measurement of emission spectra 

 consisting of diffuse bands are absorption and scattering. In this case 

 it is not possible to apply a correction for these effects to the observed 

 emission spectrum, and the only solution is therefore to make use of 

 such dilute suspensions that they may be neglected. The absorption 



M 



^—Ph phosphoreum 

 — — Ph. splendidum 



Ph fischeri 



A. mellea 



iOO 420 ««0 ~i6d i80 500 520 5iO 560 580 600 ' 620 6«0 nyi 



Fig. 8. Bioluminescence emission spectra of three species of luminous bacteria and 

 one fungus. (From Bioch. et Biopliys. Acta 5 (1950), by pemiission of 

 Elsevier Publishing Company. ) 



of the emitted light by the emitting cell itself is unknown, however, 

 and the spectra may be still in error by this amount. In the emission 

 of luminous bacteria, a calculation shows that in all probability this 

 absorption by only one cell is negligible. In luminous fungi, however, 

 one is compelled to make use of mycelial mats, consisting of several 

 layers of hyphae. Here absorption may not be without importance. 

 The spectra obtained by van der Burg (1950c) for various organ- 

 isms are reproduced in Figs. 8 and 9. What conclusions can be drawn 

 from these spectra? In the first place, it is likely that the three fungi 

 have identical emission spectra and hence identical bioluminescent 



