148 F. X. WILLIAMS 



einerley mit dem Fettkorper derselben " Peters 



('41), on page 241, says that, although the fat-body cannot be 

 mistaken for the light-organ, it seems probable that the chief 

 constituent of the latter- is fat. Leydig ('57) considers the light- 

 organ an essential part of the adipose tissue. 



Von Kolliker ('57) styles the light-organ a nervous apparatus, 

 because the albuminous material of which it is composed is 

 oxidized under the direct influence of the nervous system. He 

 believes, however, with Leydig that the organ is fatty. 



Max Schultze ('65) who studied the photogenic organ of 

 Lampyris splendidula quite thoroughly, believed that it is related 

 to the fat-body. Emery ('84), who has investigated the organ 

 of Luciola italica, considers it of fatty origin. Wieolowjski ('90) 

 thinks that the two layers of the organ differ in origin, the upper 

 or non-luminous being fat-like, the lower ectodermal, since it is 

 composed of certain oenocytes. 



Seaman ('91) upholds the derivation of the organ from the 

 fat-body. Wheeler '('92) says: "The resemblance between the 

 fat body and the light organ is so great that I do not doubt their 

 genetic relationship though I have not studied the development." 



Bongardt ('03), Berlese ('09) Dahlgren and Kepner ('08) be- 

 lieve the photogenic organ to be a derivative of the fat-body, 

 and Vogel ('13) has shown that the light-organ of Lampyris 

 noctiluca is derived directly from the fat-body. 



Pierantoni ('14) figures in section the. light-organ of Lampyris 

 and the symbiotic organ of the homopteron, Aphrophora spu- 

 maria. It must be admitted that there is a striking similaiity 

 between the two structures. The small bodies, one or two micra 

 in diameter, observed in the photogenic layer, he believes may 

 be luminous bacteria, which, as in the non-luminous bacteria 

 of the Homoptera, are inherited, since they are transmitted to 

 the egg while it is still in the ovary. 



Buchner ('14), in following the opinion of Pierantoni, sees a 

 possible relationship of the light-organ to the specialized fat- 

 body (pseudovitellus) of the Homoptera, and a support of his 

 views of symbiotic mycetoms. 



