ON LUMINOUS OKGANS OF FISHES. 



11 



PK,v-- 



inner reflector (Textfig. 4, iR) encloses chiefly the inner bul- 

 bous section of the organ. 

 Towards the exterior it 

 stretches out into a thin 

 la3^er lined by the outer 

 reflector. It is composed 

 of bundles of fine fibrous 

 '^ spicules," running par- 

 allel to one another and 

 sparsely mixing between 

 them elongate nuclei of 

 the connective tissue. It 

 appears grey with trans- 

 mitted light and shining- 

 silvery with reflected 

 light. 



Tbe outer reflector 

 [oR], which lines the 

 external section of the 

 organ in the form of a 

 funnel with the thickest 

 part of its wall at about 

 the opening of the organ, 

 is composed of fibres run- 

 ning straight outwards 

 and which appear to 

 have no silvery lustre but are quite transparent. This outer 

 reflector appears to have been overlooked by most observers. Only 

 Brauek distinguished in Slernoptyx and Ärgyropelecus a layer 

 of loosely arranged fibres which showed no silvery lustre. It 



Fig-. 4. A branchiostegal photophore of Maurolicus 

 pennanti cut transversely to the long axis of ihe fish. 

 X 80. Cr semicircular cracks in tlie photogenic body, 

 G gelatinous connective tissue, L lens, I'g pigment 

 layer, P/ü' photogenic cells of the inner fection, Pho 

 those of the outer section, IR inner reflector, oR cuter 

 reflector, V blood vessel. 



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