REPOET ON THE DEEP-SEA FISHES. 305 



they pour their secretion. Here large and conspicuous spherical bodies (nuclei ?) 

 which very readily become stained are found, surrounded by the secretion of the gland- 

 tubes (PI. LXX. fig. 23, c). 



It appears from this that these structures are very similar to those described above 

 from the proximal sac of the regular, vertical, composite organs without reflector. 



The structure of the substance which occupies the distal portion of the organ or the 

 cup, is very different and complicated. 



The bloodvessels and nerves which pass through the spicule-layer extend perpendi- 

 cularly to the surface. They are straight and sometimes supported by a slender carti- 

 laginous rod, and end just below the outer surface (PI. LXXII. fig. 44). Leydig' and 

 Emery ^ describe and figure these vessels as irregularly curved and branched, but in all 

 the specimens examined by me they were quite straight. From these vertical columns 

 slender cells radiate, which are about half as long as the vertical bloodvessels are apart. 

 They extend tangentially from their lower portion and radiate from the upper end in 

 every direction, and since they are closely packed they surround the vertical vessels on all 

 sides. In this way cylindrical or prismatic structures, rounded at their distal ends, are 

 produced, which measure about 0'2 mm. in diameter and are 0'8 mm. high. These 

 cylinders do not occupy the whole of the space, and do not touch each other, but 

 appear to be separated by a substance which forms narrow partitions between the 

 cylinders and which covers their rounded distal ends. This substance is granular and 

 contains round nuclei which stain very readily. Outside there are one or more layers of 

 very flat epithelial cells covering the whole organ. 



The elements which compose the cylinders are of particular interest (PI. LXXII. 

 figs. 43, 44). There are two kinds of cells in the radiating mass which surrounds the 

 vertical pillars, the greater number being faintly visible and indifferently spindle-shaped or 

 cylindrical (PI. LXXII. fig. 43, a). Other very peculiar club-shaped elements are found 

 between them (PL LXXII. fig. 43, h), these widen towards the distal end and taper 

 proximally to form a very long and comparatively slender peduncle which is about one- 

 fourth as thick as the club-shaped end. In the latter an oval highly refracting body 

 (PI. LXXII. fig. 43, c) is situated, which apparently consists of a cavity, with a very fine 

 wall, containing fluid. This vesicle occupies the greater part of the clul)-shapcd end 

 of the cell and is surrounded by a thin film of protoplasm only. Just below it the oval 

 nucleus is situated. The protoplasm of tliese cells as well as the nucleus stains very 

 readily. 



The appearance of thin sections renders it probable that the proximal peduncles of 

 these cells are in direct connection with the nerves, which extend upwards in the central 

 piUars of the cylinders. 



1 F. Lej-dis, Die aiigenahnliclieii Organe der Fische, pi. x. fig. 60. 

 ,,- E. Kraery, Mitiheil. aus d. r,oot. Station xu Xeapcl, Bd. v. 



(ZOOL. CHALL. EXr. — PART LVII. — 1S87.) '^'1 3^ 



