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teeth ; and the animal, when it gets anything eatable near 
its mouth, probably relaxes its stomach muscles, and stuffs the 
morsel down with its arms and mouth tentacles. They must, 
in some instances, swallow mud in large quantities — mud con- 
taining organisms with calcareous shells, and I have found 
Foraminifera in the stomach. Forbes,*' in noticing the result of 
digestion, writes with regard to the tentacles : “ They are 
continually in motion, moving up and down ; and every now 
and then when the stomach pouts up and ejects some digested 
matter, the inner tentacles shovel it up, and the outer clear 
it away. This is done with great regularity, and it is a very 
curious sight, for not only are the motions and actions of the 
tentacles admirable ; but when the stomach swells, there appear 
bright orange stripes of a most vivid metallic lustre running 
along its surface with an almost phosphorescent gleaming.” 
These remarks refer to the common Sand Star. 
The ciliated surface of the stomach is secretive also, and 
from it must come the weak acid juice which dissolves the 
protoplasm and organic matters of the food, with some pepsin 
or other. The corroding influence is seen in the minute shells 
found in the stomach, and thus a digested pabulum with some 
salt of lime is manufactured. It is destined to nourish the 
animal’s soft and hard parts to the remotest arm tip, to replace 
albumen and fibrine, refractive matter, chitinous fibre, and 
worn-out carbonate of lime of the skeleton, and to be placed in 
definite positions during growth. It has to be circulated every- 
where, and the worn-out matters have to be got rid of from the 
tissues. Substances which cannot be digested are of course 
simply removed through the mouth ; and as perfect closure of 
the mouth cannot prevail for any considerable length of time, 
much water must find its way into the stomach. Doubtless the 
chyme, if it may be so called, is much diluted, and it is wafted 
over the inside coat of the stomach over and over again by 
means of the cilia, but, beyond believing that it may enter 
stomach cells and pass from one to another, the imagination 
fails to assist in the elucidation of the problem, especially if it 
is centred in the belief in veins, arteries, and lymphatics as 
inevitably necessary physiological adjuncts to nutrition. Some 
amount of churning may go on in the stomach during digestion, 
for the muscular fibres are numerous, and are of the kind which 
is associated with involuntary rhythmical movement ; and this 
alternate contraction and relaxation may assist in the movement 
of the nutrient plasma in and through the cells. The process 
must be of the simplest kind, and this is an important consider- 
ation, for digestion is much more complicated in the Echini 
and Star-fish, which are associated with the Ophiurans in classi- 
fication. 
• Forbes, “ A History of Star-fishes,” p. 24. 
