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. These same processes serve also to catch prey
at a distance and to bring it to the mouth. They are so used by both
the Sepias and the Calamaries. In the Poulps the feet are themselves
able to perform these offices, and there are consequently no
proboscises. Proboscises and twining tentacles, with acetabula set
upon them, act in the same way and have the same structure as those
plaited instruments which were used by physicians of old to reduce
dislocations of the fingers. Like these they are made by the
interlacing of their fibres, and they act by pulling upon pieces of
flesh and yielding substances. For the plaited fibres encircle an
object in a slackened condition, and when they are put on the
stretch they grasp and cling tightly to whatever it may be that is
in contact with their inner surface. Since, then, the Cephalopoda have
no other instruments with which to convey anything to themselves
from without, than either twining tentacles, as in some species, or
proboscises as in others, they are provided with these to serve as
hands for offence and defence and other necessary uses.
The acetabula are set in double line in all the Cephalopoda
excepting in one kind of poulp, where there is but a single row. The
length and the slimness which is part of the nature of this kind of
poulp explain the exception. For a narrow space cannot possibly
admit of more than a single row. This exceptional character, then,
belongs to them, not because it is the most advantageous
arrangement, but because it is the necessary consequence of their
essential specific constitution
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