THE RADIATING ORGANS OF THE DEEP SEA FISHES. 177 
dense, and of uniform thickness in the inner spherical part and the proxi- 
mal portion of the outer pa rabolic part. ‘Towards the surface it thins out. 
The reflecting layer (Figs. 35, 37 r) is about as thick as the pigment layer 
and composed of longitudinally arranged fibrous cells. It does not extend 
to the surface and terminates some distance within the margin of the 
pigment layer. On the inner side of the reflecting layer a conspicuous 
connective-tissue membrane (Figs. 85, 87 ¢) about as thick as the two other 
layers, is met with. Distally this membrane passes into the gelatinous 
portion of the outer region of the organ. . 
Three regions (Plate 7, Fig. 37 g, |, s), can be distinguished in the tissue 
forming the internal part of this organ in Lychnopoles as in Argyropelecus 
and Sternoptyx ; in Lychnopoles, however, these are built on a somewhat 
different plan. 
From the connective-tissue membrane (Plate 7, Figs. 35, 37 c) mentioned 
above membranous diverticula extend inward which join to form facets 
arranged radially. In the proximal spherical part of the organ these mem- 
branes are straight and each facet encloses a regular pyramidal space. 
Its apex lies near the centre of the sphere, and its base abuts on the 
connective-tissue membrane overlying the reflecting layer (Plate 7, Fig. 37). 
The radial membranes (facets) do not extend quite to the axis. A some- 
what irregular tubular cavity (Plate 7, Vig. 37 cc) occupies that portion 
of the axial part of the organ which lies between the centre of the proxi- 
mal sphere and the focus of the distal pa ‘aboloid. The margin of this 
tube is so well defined that it looks as if a special limiting membrane were 
present. Its cavity appears empty, neither blood corpuscles nor other 
bodies were found in it. In the pyramidal spaces enclosed by the facets, 
nuclei and residual protoplasmatic masses highly stainable with, acid-fuchsin 
are met with. hese adhere chiefly to the connective-tissue membrane 
at the base of the pyramid and to the adjoining parts of the radial membranes: 
the central parts of the facets (Plate 7, Fig. 37 ci) are pretty free from 
them. 
The facets in the distal paraboloid are not so regular as those in the 
proximal sphere. The inner (proximal) part of the paraboloid is occupied 
by pretty narrow, more or less curved facets (Plate 7, Fig. 37, cm) extend- 
distal end of the tubular cavity above 
ing from the sides towards the 
described. These facets are pyramidal, distally broad and proximally con- 
tracted. The outer (distal) part of the paraboloid is occupied by regular 
12 
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