526 KINETICS OF BIOLUMINESCENT REACTION. I 



wave lengths (Leimbach,^ 1909). Abney/o Stark/^ Helmick/^ Ross'' 

 and others report more or less marked differences. The recent paper 

 of Ross^^ (1920) is of interest in this connection. His results indicate 

 a very considerable variation, and are of particular interest since 

 they cover in some detail the region of the spectrum in which the 

 Cypridina luminescence falls. Thus with identical exposure and 

 development the following values for gamma were obtained: \ = 

 4100A, 7 = 0.74, X = 4400A, 7 = 1.15, X = 4800A, 7 = 1.42, X = 

 5100A, 7 = 1.04. In the light of such data it will be seen that the 

 effect of the quality of the light is indeed considerable. 



It is therefore plain that for the evaluation of photographic records 

 produced by unknown light intensities it is of prime importance that 

 the calibration exposures should be produced by light of exactly the 

 same quality. The spectral distribution of light in Cypridina lumi- 

 nescence was studied by Karvey^^ (1920) who reports that visual 

 spectroscopic observation indicates a broad band spectrum extending 

 from X = 4150A to X = 6100 A, the broadest distribution yet observed 

 for any bioluminescence. The light of Cypridina is therefore decidedly 

 heterochromatic, and its photographic effect is a composite of the 

 effects of all the different wave lengths included in the light. The 

 spectral energy curve has not yet been worked out for Cypridina, so 

 it is at present quite impossible to know the relative weights of the 

 different colors involved in producing the composite effect. It is, 

 moreover, impossible to know how to match this photographic effect 

 exactly by using a light filter and a standard lamp, although such a 

 match might conceivably be obtained through a study of the effects 

 of many filters. I early decided that it would be decidedly ques- 

 tionable to employ such a colored filter-standard lamp method of 

 calibration, in the lack of accurate information concerning the energy 



'• Leimbach, G., Z. wiss. Photo., 1909, vii, 157. 



^^ Abney, W. W., Treatise on photography, London, New York, Bombay, and 

 Calcutta, 10th edition, 1901,413. 



1^ Stark, J., Ann. Phys., 1911, xxxv, 474. 



12 Hehnick, P. S., Phys. Rev., 1921, xvii, 145. 



^^ Ross, F. E., Communication No. 95 Research Laboratory, Eastman Kodak 

 Company. Also in Astrophys. J., 1920, lii, 98. 



^^ Harvey, E. N., The nature of animal light, Philadelphia and London, 1920, 

 47. 



