574 SUPPLEMENT 
Their food consists of small mollusca, shrimps, little crabs, 
and meduse. They seize them with their tentacula, keep 
them in the interior of their body for ten or twelve hours, and 
subsequently void through the same aperture the solid parts 
which they have been unable to digest. In the sea-water, 
they can support very long fasts. It has been observed 
already that the more hungry they are, the more they dilate 
their aperture; it sometimes even happens that they turn 
their stomach altogether, and render it convex, instead of 
concave, as it was before. They perish directly in fresh 
water. They are found attached by the base. When the 
animal is desirous of changing place, it possesses several 
methods of exercising this movement. It either slides slowly 
upon its pedicle, or, detaching its base altogether, it swells 
itself with water, and then becoming almost as light as the 
volume of water which it displaces, the least agitation is suf- 
ficient to impel it further. When it wishes to fix itself, the 
body contracts, the water escapes, it proceeds to the bottom, 
and its base becomes glued to the surface of the first body 
within its reach. Though no organ of vision is observable in 
these animals, a strong light evidently incommodes them. 
They appear strongly affected by it. Dicquemare has ob- 
served that those actinie from which certain parts were ab- 
stracted, were more sensible to the glare of light than they 
had been before they were mutilated. Severe cold does not 
annoy them. They may be enclosed in a piece of ice, left 
there all night, and on the following day they shall be found 
alive. Placed under a pneumatic machine, they support the 
effects of the vacuum without inflating themselves, and with- 
out appearing in the least degree exhausted when the air is 
restored to them. Dicquemare has made some further obser- 
vations which may prove useful to mariners. He perceived 
that all the changes of weather were announced by some ex- 
traordinary movements in the actiniz which he brought up; 
