STUDIES ON BIOLUMINESCENCE. 



VII. Reversibility of the Photogenic Reaction in Cypridina. 



By E. NEWTON HARVEY. 



(From the Department of Marine Biology, Carnegie Institution of Washington, 

 Washington, and the Physiological Laboratory, Princeton University, Princeton)/ 



(Received for publication, September 3, 1918.) 



In a previous paper of this series/ I have described two photogenic 

 substances in the ostracod crustacean, Cypridina hilgendorfii, which I 

 called photogenin and photophelein. Photogenin is destroyed below 

 the boiling point, is non-dialyzable, and prepared by making a cold 

 water extract of the luminous animal and allowing it to stand in the 

 air until no more light appears on shaking. This indicates that one 

 of the photogenic substances, photophelein, has disappeared, leaving 

 the photogenin. Photophelein is not destroyed by short boiling and 

 .will dialyze. It is prepared by making a hot water extract of the lumi- 

 nous animal. The hot water destroys the photogenin, leaving the 

 photophelein. Whenever two such non-luminous solutions are mixed 

 light appears. 



On the grounds of method of preparation, relation to temperature, 

 and dialysis, I regarded photogenin as comparable to luciferase and 

 photophelein as comparable to luciferin, two photogenic substances 

 described by Dubois^ in the beetle, Pyrophorus nociilucans, and in 

 the mollusc, Pholas dactylus. Dubois believes that luciferase is an 

 oxidizing enzyme which oxidizes luciferin, an oxidizable substance, 

 with Hght production. Neither luciferase nor luciferin alone in solution 

 can produce light but light appears if solutions of the two are mixed 

 and continues as long as any luciferin remains unoxidized. Dubois 

 has also been able to produce light by oxidizing luciferin (alone) with 

 a small crystal of KMn04, by H2O2 (with or without blood containing 



1 Harvey, E. N., Am. J. Physiol., 1917, xlii, 318. 

 ^ Dubois, R., Compt. rend. Soc. bioL, 1885, xxxvii, 559. 



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