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204 THE RADIATING ORGANS OF THE DEEP SEA FISHES. 
by the elasticity of the semicartilaginous rods described above or the ac- 
cumulation of blood in the large longitudinal, sinus-like bloodspace (Figs. 8, 
9 b’) which occupies the centre of the tentacular papilla. Other smaller 
blood vessels (Figs. 8, 9 b) are met with in its superficial parts. 
The longitudinal chambers formed by the connective-tissue septa men- 
tioned above, are large and dorsoventrally depressed in the dorsal leaf-like 
part, whilst they are radially arranged like a fan in the two lower lobes. 
The connective-tissue walls of these chambers are clothed by a high epithe- 
lium composed of a single layer of cylindrical cells. In the sections this 
cell layer (Figs. 7, 8, 9 pe) is, however, by no means in direct contact with 
the connective-tissue walls, but separated from them by an apparently empty 
space of considerable extent (Figs. 7, 8, 9). Thus these cylinder cells form 
tubes lying within the likewise tubular chambers formed by the connective- 
tissue septa. The lumina of these tubes (Figs. 7, 8, 9 cv) are narrow and 
either empty or occupied by a structureless mass, apparently a secretion. 
The cylinder cells themselves contain a pretty transparent protoplasm, which 
is strongly stained with picric acid, but hardly at all with haematoxylin. 
The large, oval, granular nucleus lies in the outer (lower) termination of 
the cell. Pigment is found chiefly in the outer skin of the dorsal leaf-shaped 
lobe. — 
In structure these organs resemble the inner portions of the suborbital 
organs of Pachystonias microdon (Lendenfeld ’87, p. 8320-322, Plate 71, Figs. 
30, 31), where however the cells forming the tubes are not so high. It is 
particularly to be remarked that also in this part of the suborbitals of 
P. microdon one finds in the sections the tubes formed of these cells sepa- 
rated from the connective tissue surrounding them, by apparently empty 
spaces. 
Chun (03, pp. 568, 569) has mentioned the occurrence of a frontal ten- 
tacular papilla in other species of Malthopsis. He thinks that the organ may 
emit light, but is doubtful on this point. 
On the margin of the body of this fish bud-like protruding organs of 
peculiar structure (Plate 1, Figs. 1, 2, Plate 2, Fig. 6 0) oceur, which I will 
not describe here, being of the opinion that their function is not to radiate. 
They are ramified, rich in blood vessels, and may be accessory gills, or sense 
organs. These structures are dealt with in the Appendix. 
