SEA-ANEMONES: THEIR WEAPONS 



this double fold the structure proceeds as a very slender 

 cord, which, passing back toward the anterior end of the 

 capsule, winds loosely round and round the chamber, with 

 some regularity at first, but becoming involved in contor- 

 tions more and more intricate as it fills up the posterior 

 moiety of the cavity. The fusiform chamber appears to 

 be marked on its inner surface with regularly recurring 

 serrations, which are the optical expression of that peculiar 

 armature to be described presently. 



"Under the stimulus of pressure when subjected to mi- 

 croscopical examination, and doubtless under nervous stim- 

 ulus, subject to the control of the will, during the natural 

 exercise of the animal's functions, the cnidce suddenly 

 emit their cgntents with great force, in a regular and pre- 

 scribed manner. It must not be supposed, however, that 

 the pressure spoken of is the immediate mechanical cause 

 of the emission; the contact of the glass plates of the com- 

 pressorium is never so absolute as to exert the least direct 

 force upon the walls of the capsule itself; but the disturb- 

 ance produced by the compression of the surrounding 

 tissues excites an irritability, which evidently resides in a 

 very high degree in the interior of the cnidce; and the 

 projection of the contents is the result of a vital force. 



"In general, the eye can scarcely, or not at all, follow 

 the lightning-like rapidity with which the chamber and its 

 twining thread are shot forth from the larger end of the 

 cnidce. But sometimes impediments delay the emission, or 

 allow it to proceed only in a fitful manner a minute por- 

 tion at a time; and sometimes, from the resistance of fric- 

 tion (as against the glass plate of the compressorium), the 

 elongation of the thread proceeds evenly, but so slowly as 

 to be watched with the utmost ease; and sometimes the 



