HYDRA. 79 



the arms or tentacles branch off, coiling about in 

 all directions in search of prey. The other end is 

 provided with a suctorial disc, by means of which 

 the animal attaches itself at will to floating plants 

 thus obtaining the benefit of change of position 

 without effort or to any other fixed or movable 

 object near. They are very sensitive to light ; and 

 if kept in confinement in a confectioner's glass jar, 

 one may with a hand-glass watch their movements 

 with great ease. They will collect on the side of 

 greatest light ; and if the jar is suddenly turned 

 round, the long tendrils, though hanging down 

 gracefully at the moment, will now stretch right 

 across the body of water towards the bright 

 side, as if anticipating the coming pleasure of 

 moving in that direction, which they will do if 

 undisturbed. The motion, however, is so slow, if 

 unaided by any floating object, that a few inches 

 distance takes as many hours to get over. This 

 they accomplish in more ways than one. They 

 will measure themselves by attaching the mouth or 

 a tentacle in the direction required, and then bring- 

 ing up the foot when the previous hold is dropped 

 and expanded again for another step, and so on 



