168 F. X. WILLIAMS 



Dahlgren and Kepner ('08) say with reference to the tissues 

 of photogenesis that: "The power is probably a specialization of 

 the same or similar processes to those that produce heat, motion, 

 and electricity." They do not accept the theories of Dubois 

 and do not consider the luciferine of the blood, but oxygen, the 

 reducing agent in photogeny. Of the luciferase of Dubois they 

 say: "It can be seen in sections and teased cells as a collection 

 of granules that stain very readily and retain the stain with great 

 tenacity." 



Lund ('11) studied the light-organs in fireflies from a struc- 

 tural and physiological point of view. He is of the opinion that 

 the process of photogenesis is dependent upon the presence of a 

 substance, probably of the nature of a reductase, in the presence 

 of water and oxygen, and that it is probably an oxidation process. 

 He determined that the dorsal layer of the photogenic organ 

 became "the repositories for the waste product" (of the lower 

 layer) and that 



From the facts concerning the relation, in amount, of the granular 

 deposit in the dorsal and ventral layers it is evident that we are to 

 consider the granules of the photogenic cells as at least one if not the 

 main source from which the crystalline (urate) deposit is derived. 

 . . . . From a study of the dried photogenic material we at once 

 see, as others have long ago pointed out, that the immediate process 

 of light production is not dependent upon the protoplasm of the cell 

 but upon the interactions between formed substances. 



Harvey ('14) studied the chemical nature of the luminous 

 material of the firefly and believes that the phosphorescence is 

 due to the oxidation of some substance formed in the cells of 

 the animal. He says .in part: "I can state definitely that the 

 'luciferine' of the common firefly is not a true fat or any fat-like 

 body such as lecithin The material is therefore in- 

 soluble in fat solvents It is most likely a protein 



but belongs among the proteins insoluble in water." 



Pierantoni ('14), and Buchner ('14), think that the photogenic 

 organ may be a- luminous bacterial structure. Buchner states 

 that in bacterial symbiosis in Coleoptera thus far observed, the 

 infection is through the mouth of the insect. (Dubois has made 

 numerous attempts to determine if possible whether the photo- 



