now appears fwelled, as at c, Fig. 21; the arms fhoot out from
this end; at firft three or four points only begin to (hoot, as at c,
Fig. 20, and while thefe increafe in fize, others appear between
them; they can feize their prey, and eat before their arms have
done growing. ^ In the height o f fummer, the arms will often
begin to Ihoot in twenty-four hours ; but in cold weather it will
be fifteen or twenty days before the head is formed.
Fig. 22 reprefents a polype that was cut clofe under the arms ;
this became alio a complete animal in a little time.
The fides o f a polype, that has been cut longitudinally, roll
themfelves up in different ways, generally beginning at one o f the
extremities^ rolling itfelf up m a heap, as at Fig. ig3 Plate
XXIII. B, with the outfide o f the fkin inwards; it foon unrolls itfelf,
and the cut fides form themfelves into a tube, whereof the edges
a b and e i, Fig. 15, on both fides, meet each other and unite.
Sometimes they begin to join at the tail end, at other times the
whole fides gradually approach each other. The fides join fo
dole, that from the firft moment of their junftion no fear can be
difeovered.
F'g- J4> Plate XXIII. B, reprefents a polype partly joined, as
at i b, the part c a e not yet clofed.
Fig. 2g, Plate XXIII. B, reprefents a polype, the heads o f
which have been repeatedly divided, by which means it becomes
literally a hydra.
Fig. 24
Fig. 24 reprefents a polype that had been turned, endeavouring
to turn itfelf back again, the fkin o f the anterior part lying back
upon the other | the arms varying in their direftion, being fome-
times turned towards the head, fee Fig, 24 and 26, Plate XXIIL
B, at others towards the tail. The anterior extremity c, formed
by the edges of the reverfed part a, remained open for fome
days, and then began to clofe, new arms fhot out near the old
ones, and feveral mouths were formed at thofe parts where the
arms joined the body.
Fig. 23, 25, 27, 28, reprefent the different changes that took
place in another polype that had been turned infide out, and the
different revolutions it went through before it acquired a fixed
ftate. a c always fhews the part the polype had turned back, and
a b the part it could not turn back.
A polype, which has been partly turned back, remains but a
little time in that fituation. a, Fig. 28, Plate XXIII. B, the
part where the portion it had turned back joined to the body a b j
this became ftrait, and formed a right angle with a b ; the fame
day another head appeared at e, and feveral arms, a o an, began
to fhoot from the mouth a ; at the other fide of this mouth there
were the old arms a cL The next day the portion a c was drawn
near the body, and formed an acute angle with it, as at Fig. 25.
Fig. 27 reprefents the fame fwelled, after having fwallowed a
worm. Four days afterwards it’s form had varied confiderably,
as may be feen by comparing Fig. 25 and 28, having now one-
common mouth and two finall polypes growing on it.
We