372 LUMINOUS ORGANISMS OF FAR EAST 



the fourth specimens I found among some preserved fish materials 

 at the Hachijo Branch of Tokyo-to Fisheries Experimental Station, 

 but the date of collection is unknown. The total length of the third 

 specimen was 190 mm; the diameter of the eye was 20 mm, but the 

 luminous organs had putrified. The total length of the fourth speci- 

 men was 145 mm; the luminous organ was 14 mm long, 5.5 mm wide, 

 and 1 mm thick. In a parallel section of the organ (Fig. 10) a large 

 number of glandular tubes can be seen parallel to each other and 

 extending completely across the organ from the back pigmented 

 surface to the front transparent surface, with blood vessels running 

 between them. A cross section of the organ is shown in Fig. 11. 



Harvey ( 1925 ) suggested that the luminescence is due to symbiotic 

 luminous bacteria. He cultured bacteria from these luminous organs, 

 but these cultured bacteria were not luminous. 



In a former report ( 1942 ) I noted that my culture test from the 

 organs agreed with the result of Harvey's test, although I was doubt- 

 ful of his bacterial theory. I had observed that the section of the 

 organ was quite different from those in other symbiotic luminous 

 fishes, Monocentris, Physiculus, Malacocephalus, Acropoma, and Lei- 

 ognathus, and that the organ was closed, that is, it had no duct to 

 the exterior. However, upon investigation of the large specimens of 

 Hachijo Island, I was able to find the opening from the duct in the 

 luminous organ, which I had overlooked in my former report. The 

 opening to the exterior is considered to be the small depression in 

 the dorso-anterior part of the luminous organ. There are also many 

 pores scattered over the surface of the organ. Therefore the organ is 

 of the open type and supports the bacterial theory of light emission, 

 especially since the luminescence is continuous. 



Self-Luminous Fish 



The second group of luminous fish, namely fish with a well- 

 developed luminous organ or simple skin photophores, were reported 

 by such ichthyologists as Tanaka (1908, 1912), Ishikawa (1915), 

 Nakasawa (1932), Kamohara (1936, 1940, 1952), Matsubara (1936, 

 1938, 1950), Abe (1942, 1951), Imai (1942), and Kuroda (1950). 

 However, most of these are taxonomical reports. 



Recently Abe and Nakamura ( 1954 ) reported an adult female, with 



