cae 
THE RADIATING ORGANS OF THE DEEP SEA FISHES. 195 
The compound organs of the first kind (Plate 10, Figs. 49, 51) are 
spherical and have a short process directed downwards towards the outer 
surface. They might be compared to spherical bottles with small necks 
placed upside down. The axis of the organ is vertical, parallel to the median 
plane of the fish. The ventral organs, that is, those belonging to the ventro- 
thoracic row, therefore abut nearly vertically on the surface, whilst the lateral 
ones, that is, those belonging to the anterior lateral row, are very oblique and 
enclose but small angles with the surface of the fish. In the former the 
“neck” appears cut off transversely ; in the latter, obliquely. 
The pigment sheath (Plate 10, Fig. 51 p) enclosing the organ is rather 
thin and composed of cells containing brown pigment. It surrounds all 
parts of the organ with the exception of the terminal face of the “neck.” 
As in other compound radiating organs we also find in these below the 
pigment layer a reflecting layer. This is however not at all extensive, being 
confined to the distal part of the neck-shaped portion, where it forms a ring 
(Plate 10, Fig. 51 r) surrounding the “neck.” This reflecting layer is com- 
posed of highly refractive threads. 
Within the pigment sheath and, where this is developed, the reflecting 
layer, a connective-tissue membrane is met with which entirely surrounds 
the inner cell mass and forms a perfectly closed capsule, from which diver- 
ticula extend inwards. 
The greater part of the interior of the proximal, spherical part of the 
organ is occupied by large radially arranged conic cells which converge 
towards the centre of the sphere. These cells are very similar to the conic 
elements in the inner region of the compound organs of Chauliodus barbatus 
and like them consist of a long, proximal, finely granular part (ph) not 
readily stainable, and a short, distal part (pt) showing great affinity to 
haematoxylin. The nucleus is remarkably small and situated in the distal 
staining part of the cell. These cells are divided from each other by fine 
connective-tissue membranes extending from the outer connective-tissue 
capsule radially inward towards the centre. In these membranes small 
adial blood vessels (b) can be made out. 
The “neck” of the organ (Plate 10, Fig. 951 cy) above referred to is a 
stout cylinder, circular in transverse section, the axis of which coincides with 
the axis of the whole organ. This cylinder is surrounded by an extensive 
annular cavity (s) dividing it from the connective-tissue capsule forming the 
innermost layer of the outer covering of the organ. The outer, distal, ter- 
