THE RADIATING ORGANS OF THE DEEP SEA FISHES. Ve 
separated by a clearly marked constriction (C). The proximal oval part has 
in the single organs a circular transverse section throughout; in the joined 
organs it is not so regular. The distal funnel shaped part is in life probably 
a rotation paraboloid, but on account of shrinkage appears somewhat irreg- 
ular in the sections (Fig. 24). In accordance with the smallness of the 
angle enclosed between the axis of the organ and the surface of the fish, 
the funnel abuts very obliquely on the latter; it is long on the inner, and 
very short on the outer face, a very oblique truncated cone with bulging 
parabolic sides. 
The whole organ with the exception of the funnel mouth, which is closed 
by a transparent membrane, is surrounded by a thin layer of cells containing 
a dark brown pigment. These form an outer pigment sheath (p). Inside 
this lies another sheath composed of colorless, highly refractive fibres. 
This (r) is exceedingly thick at the proximal end of the inner, oval part of 
the organ and gradually thins out from here to the margin of the funnel. 
It is most highly developed in the joined ventrothoracic organs, where it 
forms a continuous mass. The fibres composing this layer are parallel, 
pretty stout, lie close together, and extend longitudinally from the proximal 
apex of the elliptical part to the distal margin of the funnel. In life these 
fibres probably follow the curvature of the layer which they form, but are 
not otherwise bent. In sections (Fig. 24) they often form zigzag lines in the 
distal thin part of the reflecting layer (B). This also is probably attributable 
to shrinkage. 
In the tissue occupying the proximal and central part of the interior 
space surrounded by the fibrous layer three regions can be distinguished : 
an inner (@), a middle (1), and an outer (s). The limits between these regions 
are well defined. The inner region extends to the constriction between the 
oval and conic part of the organ and there ends with a slightly convex sur- 
face vertical to the axis. In the joined organs, particularly in the ventro- 
thoracics, the inner regions of adjacent organs coalesce to form extensive 
cellular masses surrounded by common fibre and pigment, sheaths. 
The tissue occupying the inner region (¢) has in all sections, whatever 
their direction may be, an alveolar or reticulate appearance ; in the alveoles 
or meshes residual masses of protoplasm and small spherical nuclei, both 
readily staining with haematoxylin, are clearly visible. Very rarely a slight 
indication of an arrangement of the meshes of this network in rows is met 
| 
with. The meshes or alveoles are about 20 » wide. Occasionally one sees 
