46 The Production of Light by the 



laboratory the light from both species lasts between 7 and 8| hours. 

 While the fish occur the year around, they are most easily obtained 

 in October-November and April-May, during the change of monsoon, 

 when the weather is calm. They differ in this respect from the lumi- 

 nous squid {Watasenia scintillans) of Japan, which come in toward 

 shore to spawn at only certain seasons of the year and then return 

 to the deeper water. Although the Banda Sea about these islands 

 is very deep (12,000 feet), these luminous fish keep near the surface, 

 living in the relatively shallow water immediately around or between 

 the islands of this volcanic archipelago. They are not so readily 

 caught on moonUght nights, but this is because their light can not 

 be so easily seen by the fishermen and not because they avoid the 

 light of the moon or show any such periodicity in appearance as 

 that of the palolo or other worms. 



Nothing is known of the life history of these fish. In October 

 eggs can be squeezed from the females of both species. These are 

 surrounded by jelly, are transparent, and contain large oil droplets, 

 but sink in sea-water. Eggs of Photoblepharon are about 1.7 mm. 

 in diameter, and those of Anomalops 1 mm. in diameter, without the 

 jelly. Anomalops eggs plus sperm did not develop under laboratory 

 conditions, but these were not very favorable. They showed no 

 luminescence on stimulation mechanically, or upon the addition of 

 ammonia to the sea-water containing them. 



It is quite natural that the earlier observers, with preserved 

 material at their disposal, should be ignorant of the purpose of the 

 luminous organ. Boddaert thought the function of the organs of 

 Photoblepharon was to shield the eyes of the fish from injury by the 

 branches of the coral among which it lived. Lacepede thought it 

 a protection of some sensitive tissue against the rays of the tropical 

 sun. Giinther first considered that the structures were light-organs, 

 while Vordermann (1900) actually observed the living fish in 1897 

 and saw its light. The short paper of Vordermann and the descrip- 

 tion recorded in the narrative of the Siboga expedition by Weber 

 (1902) contained all our knowledge of these fishes until the appear- 

 ance of an extensive paper by Steche (1909). This excellent mono- 

 graph deals largely with the histology of the luminous organ and also 

 contains a few^ physiological observations. Thus, Steche determined 

 that the light shone day and night continuously with an intensity 

 (for one organ of Photoblepharon) of 0.0024 meterkertze. Mechanical 

 pressure or chemical stimulation is quite unable to increase the 

 intensity of the fight, which can be "turned off" completely or not 

 at all only by mechanical contrivances connected with the organ. 

 Discussion of Steche's histological observations wull be given in 

 describing the histology of the organ. 



The Anomalops obtained by me varied in length from 4 cm. to 

 11 em. Photoblepliaron is about the same size, but the proportions 



