THE RADIATING ORGANS OF THE DEEP SEA FISHES. 17 
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facets are nearly straight throughout the whole of their length. As we 
approach the proximal part of the facet we find these cells curving away 
more and more from the walls of the facet so that their free ends come to 
lie more or less obliquely (Plate 7, Fig. 34 sc). Finally they are situated 
nearly transversely, the cells arising from the different sides interlacing 
axially. : 
In the sections one often finds a circular structure of considerable size 
(Plate 7, Figs. 34, 35 0) in the centre of the facet. Sometimes it appears as 
an empty space, and is perfectly colorless and structureless; sometimes it 
has——in sections stained with acid-fuchsin—a bright red color and then 
one occasionally notices traces of a granular structure within it. The tissue 
surrounding the circle often shows a fine radial structure (Plate 7, Figs. 34, 
35). Ihave not been able to ascertain the real nature of these circles and 
their coronas with any degree of certainty. The circles seem to be the 
expression of spherical spaces lying between the cells, and the radial 
structure surrounding them might be due to the fact that the slender inner 
terminations of the spindle cells abut vertically on this sphere. 
The organ is rich in blood vessels. These follow the facet walls and 
can often be traced for a considerable distance. 
The gelatinous tissue (Plate 7, Figs. 34, 37 gl) mentioned above is com- 
posed of a gelatinous ground substance ti ‘aversed in all directions by exceed- 
ingly slender spindle cells. It passes into the connective-tissue membrane 
overlying the reflecting layer. A thick granular lamella or cushion (Plate 7, 
Fig. 37 er) underlies this gelatinous tissue and separates it proximally from 
the reflecting, and distally, where this is absent, from the pigment layer. 
As mentioned above, the anteorbital radiating organ differs in some 
respects from the others. It appears to be much larger and measures 
1.5 mm, in diameter. Closer examination shows that it is a duplex organ 
composed of two, each similar to the other radiating organs of the fish. 
These two organs point different ways and are enclosed in a common pig- 
ment sheath which has the shape of a curved tube open at both ends. The 
two orifices of this tube lie in the surface ; one is oblique, directed upwards 
and forwards towards the eye, the other vertical, directed straight down- 
wards. The spherical parts (inner regions) of the two organs occupy its 
central, the paraboloidal parts (middle and outer regions) and the gelatinous 
and granular tissue the terminal portions of the tube. These two joined 
organs throw their radiation in different directions, one into the field of 
