the british - Corning Museum of Glass

xvi
INTRODUCTION.
touched with instruments without much effort at contraction.
The gular tube is remarkably corrugated longitudinally,
the folds being so full, that a transverse section would
present a series of figures 8. In the present state of contraction
there were horizontal corrugations also. At a
short distance below the mouth the stomach ends abruptly,
the edge, thin and delicate, hanging freely like a much
folded curtain into the cavity. At each angle of this
flattened sac the gonidial groove was conspicuous from top
to bottom, inclosed by two slender columns of the firm
cartilage-like muscle.
The diameter of the digestive tube is, when at rest, not
greater than that of the mouth; indeed, the walls are in
contact; nor, so far as my observation extends, are they
ever separated except for the reception of food.
It has been customary to represent the stomach as a sac
pierced at the bottom " by one or more valvular openings
which communicate with the cavity of the body."* But
the case is as I have stated it: the free folded membrane
hangs perpendicularly ; nor is there any thickening of the
edge, nor any structure which at all resembles a sphincter.
In tall specimens, I have observed, through the semitransparent
integuments, food pass into the stomach, and
have marked that the morsel is invariably retained, never
passing through to the general cavity; but I am persuaded
that this is effected by the common contractility of the
walls, and not by a sphincter.
When morsels of food, such as fragments of butchers'
meat, are swallowed by Anemones, they are retained for
some hours, and then vomited; and because little change
has passed upon the solid parts it has been rashly concluded
that no process of digestion takes place in these animals.
On this foolish hypothesis it is difficult to see why food
should be swallowed at all, or what need the animal has of
mouth or stomach. Their ordinary food, however, is not
mammalian muscle, but the far softer and more fluid flesh
of Crustacea, Mollusca, and Annelida. Nothing is more
common than to find large specimens of A. mesembryanthemum
or T. crassicornis discharge, soon after their capture,
* Siebold's Comp. Anat. § 37. " The stomach with its circular aperture
at the base " (Teale). Johnston, indeed, denies it any aperture at all:—
" There is no — other visible exit from the stomach than the mouth."