168 THE WORLD OF THE SEA. 
duced by the undulation of their bodies, and by the contractions 
of their feet. These feet are sometimes in one place in the centre 
of the animal, forming a kind of disc, on which it crawls, after 
the fashion of a snail. Sometimes, however, they are placed all 
along the body, and in the Cucumaria frondosa, a holothuria found 
in the North Sea, they form five longitudinal rows. Many of the 
species are armed with small projecting hooks or fangs, which 
enable the creature to hang for a few seconds to foreign bodies. 
When these hooks adhere to the hand they produce an intoler- 
able itching. 
Lesson describes a holothuria, caught in the South Sea Islands, 
which was more than a yard long, and could contract itself into 
a few inches. The surface of its body was lubricated with an 
HOLOTHURIA ELEGANS. 
irritating fluid, which was acrid and corrosive, and when incau- 
tiously touched, the hand was affected with the burning itching 
to which we have alluded. 
But the most remarkable feature in the sea cucumbers is the 
extraordinary power they possess of ejecting the whole contents of 
their sac when they are irritated or frightened. This phenomenon 
is most inexplicable, and it is well occasionally to note that there 
are things utterly beyond our comprehension. Dr. Johnson relates 
that for some days he had forgotten to supply a holothuria with 
fresh water. The creature became sick and dejected (we might 
well be the same); soon—either in prospect of death, or hurt at 
the doctor's neglect—it ejected its tentacles, its teeth, its digestion 
tubes, and a portion of its ovaries. These were laid scattered here 
and there at the bottom of the aquarium. The muscular effort 
to have had such an effect must have been terrible. Still, what 
