370 



LUMINOUS ORGANISMS OF FAR EAST 



An interesting feature of the Japanese species L. rivulatum is that 

 the luminous gland of the male is either very large or very small. 

 I am of the opinion, though by no means certain, that this difference 

 in size is due to age. The luminous gland of the female is smaller 

 than that of the male and therefore gives off a weaker light. 



I was able to obtain pure cultures of luminous bacteria from vari- 

 ous species of the fish caught at different times in Japanese and 

 tropical waters. They had the same general biological characteristics, 



Fic. 9. The eye of the luminous iish Anomalops, showing the eUiptical white 

 himinous organ with its opening (OP). 



with only shght variations, probably due to the effects of tempera- 

 ture. All these luminous bacteria appear to be of the same group. 



The famous luminous fish Anomalops is found not only in the East 

 Indies but also in the South Pacific Islands, the New Hebrides, Fiji, 

 and Paumotus. This fish has a large half -moon shaped luminous organ 

 below the eye, as shown in Fig. 9. The back of the organ is covered 

 with a layer of black pigment. Anomalops is able to shut o£E its 

 display of luminescence at will, by rotating the organ, so that the 

 luminous part is turned away from sight and the black nonluminous 

 back takes its place. 



