186 THE EADIATING OKGANS OF THE DEEP SEA FISHES. 



noptjx ; the inner polyedrical cells on the other hand resemble the cells 

 of the middle region of the organs of these fishes. 



Three of the simple radiating organs with pigment sheath in the barbel 

 are joined to form a composite mass. Two of these are irregular and lie 

 symmetrically right and left opposite each other. The third is a regular 

 one and lies between the other two. The axes of the two former lie 

 in a plane vertical to the axis of the barbel ; the axis of the latter is ori- 

 entated longitudinally, parallel to the axis of the barbel. A close inspection 

 of a continuous series of sections through this organ reveals the remarkable 

 fact that the central one of these three organs is completelt/ enclosed by the 

 pigment layer on all sides, a thing I have not observed in any other radiat- 

 ing organ, although Leydig ('79, p. 369) mentions having occasionally 

 seen simple organs with pigment sheath of C. sloani thus entirely enclosed by 

 pigment. Supposing, as one surely has a right to do, that the pigment sheath 

 intercepts the radiation, we would have in that organ of the barbel, and in 

 the similar ones observed by Leydig, radiating organs unable to radiate. 

 A careful examination of these organs completely surrounded by pigment in 

 Chauliodus may be warmly recommended to future investigators. 



According to Chiarini's description (00, p. 10, Plate 5, Fig. 6) the simple 

 radiatuig organs with pigment sheath of Chauliodus sloani are very similar; 

 his figure (6) however differs somewhat from mine (Plate 9, Figs. 43, 44). 

 Chiarini states that in staining the superficial cylinder cells with haema- 

 toxilin-eosin the nucleus absorbs the former, the protoplasm the latter. 



The compound radiating organs with pigment sheath (Plate 9, Figs. 45, 

 46) on the body are directed downward. Their axis is vertical, and parallel 

 to the median plane of the fish. Thus the angle between it and the adjacent 

 part of the surface is much larger in the ventral rows than in the lateral- 

 In the latter it is very small, often appearing to be nearly nil, the axis then 

 being approximately parallel to the adjacent surface. In their external 

 shape these organs resemble the compound organs of Lychnopoles argenteolus 

 described above. They are composed of a proximal spherical (Plate 9, Fig. 

 45 A) and a distal paraboloidal part (D). These parts are separated by a 

 sharp and well-defined stricture (C) of considerable depth. The proximal 

 part forms about three quarters of a very regular sphere. The distal part 

 is short, broad, and cut off obliquely at the base, where it abuts on the sur- 

 face. With the exception of the oblique terminal face of the distal para- 

 boloidal part, the whole organ is enclosed in a stout pigment sheath (Plate 



