LUCIFERIN AND LUCIFERASE 381 



cent fruit-bodies of fungi do not give out light without the presence 

 of oxygen is shown by the experiments of Kawamura described 

 above ; and that they do not give out light without the presence of 

 water is shown by my observation that fruit-bodies of Panus stypticus 

 cease to give out light when dried, and resume their emission of 

 light when again moistened. 



Pfliiger, in 1875, looked upon luminescence simply as a sign of 

 intense respiration ; and Beijerinck, in 1915, regarded the light as 

 an accompaniment of the formation of living matter from peptone.^ 

 Molisch (1904) and others, however, held the view that light-giving 

 organisms contain a definite substance which undergoes oxidation 

 and thus causes the emission of light. Molisch called this supposed 

 substance photogen.^ 



In 1885-1887, Dubois made some important experiments on the 

 mollusc Pholas dactylus. He found (1) that a hot-water extract of 

 the luminous tissue emits no light, (2) that a cold water extract 

 emits light for a certain time, and (3) that, if a hot-water extract 

 and a cold-water extract no longer producing light are mixed 

 together, they again produce light. Dubois, in 1887, therefore 

 " advanced the theory that in the hot-water extract there is a 

 substance Ivciferin, not destroyed by heating, which oxidises with 

 light production in the presence of an enzyme luciferase, which is 

 destroyed by heating. The luciferase is present together with 

 luciferin in the cold-water extract, but the luciferin is soon oxidised 

 and luciferase alone remains. Mixing a solution of luciferin and luci- 

 ferase always results in light production until the luciferin is again 

 oxidised." ^ Harvey found similar substances in some American 

 fireflies {Photinus and Photuris), a Japanese firefly (Luciola), and in 

 an ostracod crustacean, Cypridina hilgendorfii, and Crozier found 

 them in Ptychodera, a balanoglossid. However, Harvey could not 

 demonstrate their existence in luminous bacteria, in the annelid 

 Chaetopterus, in certain pennatulids, in a squid, and in a fish ; but 

 he points out that there are several reasons why the existence of 

 luciferin and luciferase might be difficult to demonstrate.* It may 



1 E. N. Harvey, The Nature of Animal Light, 1920, p. 102. 



2 H. Molisch, loc. cit., p. 109. 



3 E. N. Harvey, loc. cit., p. 103. ■* Ibid. 



