16 THOUGHTS ON ANIMALCULES. 



If a piece of stem or leaf to which some polypes 

 are attached, is put into a small clear phial filled with 

 water, and placed on the cell of a window where the 

 objects can be conveniently examined, the little animals 

 will in a short time extend and spread out their arms 

 inquest of prey; and, if a small lively worm is dropped 

 into the water, they quickly rouse into full activity, 

 while the worm, apparently conscious of its danger, 

 throws itself into violent contortions. One of the 

 polypes then stretches out its arms, perhaps to the 

 length of several inches, till they become as attenuated 

 as a spider's web, and suddenly seizes and entangles its 

 prey, (see pi. I, fig. 3, c), which in a moment, as if 

 paralysed by an electric shock, ceases its struggles, and 

 is then slowly drawn to the mouth, and swallowed, (see 

 pL i, fig. 7), The body of the hydra now becomes dis- 

 tended; digestion rapidly takes place, as is shewn by the 

 diffusion of the red colour of the worm through the sub- 

 stance of the polype; and, after some hours, the indigest- 

 ible portions are rejected by the mouth. 



In watching this experiment, the extraordinary pow- 

 ers possessed by the tentacula those apparently mere 

 attenuated threads cannot fail to arrest attention. 

 ^These instruments, when stretched to the utmost, (see pi. 

 i, fig. 3), are as fine as the finest cobweb; but a high 

 magnifying power shews them to be tubular, and filled 



