OF POLYPKS. 



35 



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 ; i'ig- 3. 



and from tlie incessant revolution of 

 particles within the mouth and the gul- 

 let, observed by Professor Grant, this 

 oro-an 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 (5,) of ))erfect 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 {d,) 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 vvilling to believe performs the functions of the liver,* 

 an opinion in which I am disposed to concur. 



see Dr Sbarpey's article " Cilia" in the Cyclopsedia 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 do I'estomac, des rangces d'organes en forme de petites taches jaunatres, 



