LUMINESCENCE 



551 



13.12). The brachial light-organs consist of a central mass of large photo- 

 genic cells surrounded by a sheath of connective tissue and a chromato- 

 phore screen (Fig. 13.14(6)). The ocular organs are simple flattened 

 structures provided with a lens-like body of connective tissue and bounded 

 externally by a layer of radiating rods. More remarkable are the small 



Fig. 13.12. Luminous Deep-sea Squid 



(a), (b) and (c) lateral and ventral views of Lycoteuthis (Thaumatolampas) diadema; 

 (d) ventral view of Abraliopsis morisii. (After Chun, 1910.) 



bead-like organs dispersed over the body and illustrated in Fig. 13.14(a). 

 These have a complicated reflector consisting of two lamellated masses and 

 an external lens suspended in a fibrous support. Corresponding photo- 

 phores found in Lycoteuthis and Calliteuthis are provided with external 

 coloured layers or chromatophore screens on the light-emitting surface 

 (Fig. 13.13(6)). In some of these organs a nerve supply has been described 



