OF POLYPES. 
35 
Fig. 3. 
to perform the office of breathing organs by keeping up a constant 
current of water along their surfaces, which sets in towards 
the mouth in an invariable direction ; 
and from the incessant revolution of 
particles within the mouth and the gul- 
let, observed by Professor Grant, this 
organ seems to be also ciliated internal- 
ly. The more especial use of the ten- 
taculais to arrest the prey which chance 
floats within their reach and conduct it 
to the mouth, — a simple aperture pla- 
ced in the centre of the tentacular cir- 
cle, and which is armless, having in no 
instance either jaws or teeth. It is the 
entrance into a long membranous gul- 
let ( b ,) of perfect transparency, and 
which can be traced through its equally transparent envelope, 
to its termination in a somewhat globular and comparatively 
large organ placed near the curvature of the body, and render- 
ed opaque partly by the greater thickness and fleshiness of its 
structure, but perhaps more so by the nature of its contents. 
This is the stomach ( c ,) and from the side of it there proceeds 
a narrow intestine (t/,) which follows a straight upward course 
along the side of the gullet, and opens at the aperture of the 
cell by a separate orifice, from which the undigested remains of 
the food are ejected. There is another organ of a roundish 
figure appended to the bend of the intestine, which is supposed 
by some to be an ovarium (e,) but it seems not unnecessary to 
remark, that this appropriation of it to the generative function 
has perhaps no better proof than what is derived from a similari- 
ty of position between it and the supposed ovarium of the com- 
pound mollusca. It is, I presume, the organ which Blainville 
says he is willing to believe performs the functions of the liver,* 
an opinion in which I am disposed to concur. 
see Dr Sharpey’s article “ Cilia” in the Cyclopaedia of Anatomy and Physiology, 
Vol. i. p. 609. 
* Manuel d’Actinologie, p. 72. — In the Actiniae, Blainville adds, it is almost 
certain that there is no Liver ; nor in the Hydraform polypes ; but in the Pen- 
natulae “ disseques vivans ou tres-frais, on remarque, dans les parois memes 
du corps de I’estomac, des ran gees d’organes en forme de petites taches jaunatres, 
