44
THE SEAS
This habit of delibemtely—parting with limbs which are—later
..
regener_ated is ealled
“
autotomy? and.is not conned to the
being widespread aniongst ithe starSh—--and
__
their delicate allies, the brittlestars. ”Both of these part
'
with their arms very readily and quickly grow new ones;
they may lose all their arms and yet from the central disc
there will grow out a complete new set (Fig. 6).
The related sea gherkins have the more unique power
of
,,
.
casting up their viscera
_
,
_
.
..
'
.
whendisturhedor attacked,
.
.
-
.
then proceeding,at their
,
leisure to grow new ones.
-
-
It may well be that, under
,
-
'
normal
conditions,
the
Î
_
attacker is satised with '
'
'
-
'
the meal of soft entrails
_:
:—:
{—
thus provided, and will not
-
;_
trouble their owner further.
'
f-_;£
The worms
have
excep'
' _
,
tional powers of regenera—
î
tion and when out
two
,
-
_
_
éœcidentally—or by design
TwoFlsGtäËe;—ÊaÊSËn IÎËÊnerating
arms.
in
the
laboratory — Will
tram a single sevÊreâ
ËËÎÊ ;' grow new heads 01“ tails - '
;
—
,“"’“°‘y
'
'
»
with equal facility.
_
Sponges have probably the most remarkable powers Ain"
this direction,
for
&
sponge
can
be broken into tiny
fragments which are then strained through ne meshèd
,.Silk, and yet the isolated pieces will come together and
unite to form new individuals !
,
»
,
'
,
' _
We
are leaving a COSÎd6I&üOn-0f parasitism__and of the -mt1mate, mutually advantageous union of two—animals or "
an
animal and a plant, known as symbiosis,
Chapter IX,
b“? we. must say something here of that
form Of"
'