368 LUMINOUS ORGANISMS OF FAR EAST 



Dr. Yasaki and I (1936) had reported that there were 10 species 

 of the Macrouridae, which are closely related to the Gadidae and 

 have a luminous organ of the same type. I ( 1938-1951 ) have added 

 one species of the Gadidae and 4 species of the Macrouridae and I 

 was able to obtain several strains of luminous bacteria from each 

 species of the Gadidae and Macrouridae. These strains of bacteria 

 were obtained from various species of fish caught at different times 

 and in different localities. All the bacteria had the same general bio- 

 logical characteristics but they varied in their optimum temperature, 

 being higher in some cases but never varying greatly. I think all 

 these luminous bacteria are of the same group. 



Fish with Indirect Emission Luminous Organ 



The fishes of the families Acropomatidae and Leiognathidae possess 

 luminous glands containing symbiotic luminous bacteria. These fishes 

 can also be classified under the third group since the luminous gland 

 hes inside the body and the hght therefore passes through a trans- 

 lucent area of muscles. 



Acropoma is a genus of fish of the family Acropomatidae found in 

 the southern Sea of Japan. Acropoma japonicum Gunther is known 

 as Hofani-jako in Japanese, meaning firefly small fish, and is consid- 

 ered there to be a single species. However, I have observed that the 

 luminous organ varies in shape and position in two types of fish. For 

 this reason they may represent different species. 



Recently Matsubara (1953) reported another new species named 

 Acropoma hanedai Matsubara, which I (1950) had mentioned as the 

 second type of Acropoma. During the winter season they occur in 

 southern Japan as a mid-water dweller, in depths ranging from about 

 80 to 200 fathoms. They are a beautiful pink in color and attain a 

 length of 200 mm. There is no difficulty in obtaining specimens in 

 the Mimase fish market near the city of Kochi, Shikoku, Japan. 



These fish differ from other luminous fish in possessing an unusually 

 large luminous area. In fact, the lower part of the muscles of their 

 entire body surface is utilized for this purpose. 



The diffused light comes from a luminous U-shaped filiform body 

 in the muscle tissue not visible from the outside. It consists of the 

 luminous gland, white reflector, lens, and an opening near the anus 



