THE EADIATING ORGANS OF THE DEEP SEA FISHES. 185 



edrical cells in the centre, and cylindrical elements on the surface. The 

 latter (Plate 9, Figs. 43, 44 pc) resemble a cylinder epithelium clothing the 

 pigment sheath and distal connective-tissue membrane internally. They 

 are not vertical to this surface however, but so arranged as to converge 

 to a point within the organ very near its proximal apex. In the distal 

 part of the organ these cells are short, hardly longer than broad. Inwardly 

 they increase very rapidly in length and those situated at the sides are 

 nearly half as long as the organ itself. The nucleus is conspicuous, spheri- 

 cal, or radially extended, oval, and always situated at the distal end of the 

 cell. The protoplasm is granular. The limits between these cells are 

 distinct enough distally, but become very indistinct centrally and finally 

 vanish altogether ; in the proximal part of the organ to which these cells 

 converge, no trace of cellular division is discernible. This part of the organ 

 is occupied by a granular protoplasmatic mass (Plate 9, Figs. 43, 44 m) 

 in which neither cell walls nor nuclei are met with. The proximal apex 

 itself is in the regular oval organs free from these cells, or cells of any kind, 

 the granular mass (m) extending here right up to the pigment sheath 

 (Plate 9, Fig. 43). In the axial sections of irregular organs, however, a net- 

 work of cell limits with nuxjlei in the meshes is usually observed in the part 

 appearing as the proximal apex (Plate 9, Fig. 44). It seems to me, however, 

 that this point does not exactly correspond to the proximal apex of the 

 regular organs and that the " cells " seen there are transverse sections of 

 the same kind of superficial cylinder cells as appear cut longitudinally else- 

 where. These organs being so very irregular in shape, an irregularity in 

 the arrangement of the superficial cylinder cells, giving rise to such an 

 appearance of axial sections, would be not at all surprising. 



The inner mass of polyedrical cells (Plate 9, Figs. 43, 44 1) has the shape 

 of a bee-hive or truncate cone resting with its broad base on the distal 

 cylinder cells and extending inward a good way beyond the centre of the 

 organ. The distal cells of this mass are smaller and arranged irregularly, 

 the proximal ones larger and situated in more or less clearly pronounced 

 longitudinal rows. In their appearance these cells differ essentially from 

 the cylindrical elements surrounding them. Their nuclei are pretty large, 

 spherical, or flattened radially, and their protoplasm is transparent and free 

 from granules. Picric acid stains them a bright yellow. The superficial 

 cylindrical cells are comparable to the cells forming the inner region of 

 such radiating organs as those described above of Argyropelecus and Ster- 



