ISO ANTHOZOA HYDROIDA. 



and the disposition of the zoophyte is evidently sedentary j but the 

 contractions and mutations of the body itself are sufficiently viva- 

 cious, while in seizing and mastering its prey it is surprisingly 

 nimble, seizing a worm, to use the comparison of Baker, "with as 

 much eagerness as a cat catches a mouse." It is dull, and does not 

 expand freely in the dark, but enjoys light ; and hence undoubtedly 

 the reason why we generally find the Hydra near the surface and in 

 shallow water. 



The Hydrae are very voracious, feeding only on living animals ;* 

 but, when necessary, they can sustain a fast of many weeks, without 

 other loss than what a paler colour may indicate. Small larvae, 

 worms, and entomostracous insects seem to be the favourite food 

 and to entrap these they expand the tentacula to the utmost, and 

 spread them in every direction, moving them gently in the water to 

 increase their chances ; and when a worm touches any part of 

 them, it is immediately seized, carried to the mouth by these flexible 

 and contractile organs, and forced into the stomach. " Tis a fine 

 entertainment," says Baker, " 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 ex- 

 tremity 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 shows 

 when he perceives a heavy fish at the end of a single hair-line, and 

 fears it should break away. Contracting the arm that holds it, 

 by very slow degrees, he brings it within the reach of his other 

 arms, which eagerly clasping round it, and the danger of losing it 

 being over, all the former caution and gentleness is laid aside, and 

 it is pulled to the polype's mouth with a surprising violence." {- 

 Sometimes it happens that two polypes will seize upon the same 

 worm, when a struggle for the prey ensues, in which the strongest 

 gains of course the victory ; or each polype begins quietly to 

 swallow his portion, and continues to gulp down his half, until the 

 mouths of the pair near, and come at length into actual contact. 

 The rest which now ensues appears to prove that they are sensible 



* In confinement, however, Trembley found that they might be fed on minced fish, 

 beef, mutton, or veal. Mem. 104. 



t Hist, of the Polype, 65. Also Roget's Bridgew. Treat, ii. 76. 



