87 



The food in the stomach has a rapid rotatory motion while 

 it remains there, and is conveyed through the terminal tube 

 in the same manner. Dr. Farre in an elaborate and cxcelhint 

 article on this subject says this rotatory motion is cflected by 

 vibratory cilia, similar to those of the (entacula. 



Even from this brief notice of the anatomy of the polypes 

 it will be seen that they are considerably elevated al)Ove 

 those of the foregoing orders ; and their activity and in- 

 telligence are equally superior. When fully expanded and 

 ill search of prey, turning from side to side, with their tcn- 

 tacula in constant and graceful action, they seem like animated 

 flowrets; but the suddenness of their disappearance is almost 

 beyond belief; more resembling the visions of a fairy tale 

 than any reality. How this is effected will now be explained. 

 The principle is alike in all the families, however widely 

 they may differ in external characters. For the sake of 

 brevity, it will, therefore, be described only as it occurs in 

 the VesiculariadaD, &c. The cells in this family for the most 

 part, resemble grains of wheat in shape. In these, the polype 

 bides itself. The inferior portions of the cells are inllexibly 

 horny, while the upper parts are thinner and more membranous. 

 On the internal surface are distributed a few flat muscles, which 

 are attached to different parts of the polype; thus for instance, 

 one is attached to the base of the stomach and the base of 

 the cell ; others at the sides of the cell and to corresponding 

 parts of the polype; th«ir origins or fixed points always 

 being below their insertions. These are the muscles which 

 belong to the polype; there are others which belong ex- 

 clusively to the cell. The upper portion of the cell, being 

 membranous and flexible, is operated on by muscles which 

 having their origins on the upper part of the inflexible portion 

 of the cell, then ascend and are inserted into the thin edge of 

 the orifice. Here then we see there are two sets of levers, 

 arranged in the best possible manner for rapidity of effect. 

 By them the polype can be instantaneously withdrawn, and 

 the opening drawn closely and tightly together. 



The upper rim of the cell, when the polype is expanded, is 

 found to be surmounted by a coronet of long delicate bristles, 

 which are held together by a membranous connection ; and 

 when the polype is withdrawn, these remain closely compacted 

 in an upright position at the entrance of the cell. The mus- 

 cles are composed of simple fibres, of nearly equal thickness 

 throughout, and with but very slight attachments to each 

 other. They are in fact the simplest form of muscle I ever 

 saw. This then is the mechanism of the rapid movements of 

 the polype; but the way in which they protrude is not so 

 clearly to be explained. The retractor muscles being in a 

 relaxed state, the sides of the polype which are also said to 



