HYDRA. 183 



of the glass, with its body and its tentacula extended, in 

 which position it is " as vigilant as a spider in the centre of 

 its web, fully intent on prey, and will seize a worm with as 

 much eagerness as a cat catches a mouse." " I have often 

 seen them thus situated, extending and waving their arms 

 in the water, several inches long, and so exquisitely slender 

 as not to exceed the thickness of the finest cobweb; yet 

 their sense of feeling is so delicate, that if a worm touches 

 even the utmost extremity of these very slender arms, they 

 immediately lay hold of it, and, contracting themselves to 

 about the middle length, by clasping their arms about it, 

 they envelope and fetter it in so many places, and to such a 

 degree, that notwithstanding it be much larger, and seem- 

 ingly stronger, it is soon rendered incapable of struggling 

 to any purpose." " 'Tis a fine entertainment to behold the 

 dexterity of a polype in the mastering its prey, and observe 

 with what art it evades and overcomes the superior strength 

 or agility thereof. Many times, by way of experiment, I have 

 put a large worm to the very extremity of a single arm, 

 which has instantly fastened on it with its little invisible 

 claspers. Then it has afforded me inexpressible pleasure to 

 see the polype poising and balancing the worm, with no 

 less seeming caution and judgment than a skilful angler 



