Adaptations of Fishes 67 
dition. All of these, however, are greater or less modifications 
of one type. This type includes, according to von Lendenfeld’s 
views, three essential parts, z.e., a gland, phosphorescent cells, 
and a local ganglion. These parts may have added a reflector, 
a pigment layer, or both; and all these may be simple or com- 
pounded in various ways, giving rise to the twelve classes. 
Blood-vessels and nerves are distributed to the glandular por- 
tion. Of the twelve classes direct ocular proof is given for 
one, i.e., ocellar organs of Myctophum which were observed by 
Willemoes-Suhm at night to shine ‘like a star in the net.’ Von 
Lendenfeld says that the gland produces a secretion, and he 
supposes the light or phosphorescence to be produced either 
by the ‘burning or consuming’ of this secretion by the phos- 
phorescent cells, or else by some substance produced by the 
phosphorescent cells. Furthermore, he says that the phos- 
phorescent cells act at the ‘will of the fish’ and are excited 
to action by the local ganglion. 
‘Some of these statements and conclusions seem insufficiently 
grounded, as, for example, the supposed action of the phos- 
phorescent cells, and especially the control of the ganglion 
over them. In the first place, the relation between the ganglion 
and the central nervous system in the forms described by von 
Lendenfeld is very obscure, and the structure described as a 
ganglion, to judge from the figures and the text descriptions, 
may be wrongly identified. At least it is scarcely safe to 
ascribe ganglionic function to a group of adult cells so poorly 
preserved that only nuclei are to be distinguished. In the 
second place, no structural character is shown to belong to the 
‘phosphorescent cells’ by which they may take part in the 
process ascribed to them.* 
‘The action of the organs described by him may be explained 
on other grounds, and entirely independent of the so-called 
‘ganglion cells’ and of the ‘ phosphorescent cells.’ 
* The cells which von Lendenfeld designates ‘phosphorescent cells’ have 
as their peculiar characteristic a large, oval, highly refracting body imbedded in 
the protoplasm of the larger end of theclavate cells. These cells have nothing 
in common with the structure of the cells of the firefly known to be phos- 
phorescent in nature. In fact the true phosphorescent cells are more probably 
the ‘ gland-cells’ found in ten of the twelve classes of organs which he 
describes. 
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