198 THE MECHANICAL FUNCTIONS. 



tracted state. When their tentacula, which sur- 

 round the mouth, and are very numerous, are 

 fully expanded, (as shown in Fig. 87,) these 



86 



animals present a striking analogy of form to 

 many of the compound flowers ; and accordingly 

 the particular species are named from these re- 

 semblances, the sea-anemone, the sea-marygold, 

 the sea-carnation, the sun-flower, daisy, &c. Ac- 

 tiniae are seen in great numbers on many shores, 

 adhering by their flat surfaces to rocks, and 

 being generally permanently fixed to their abode. 

 When the weather is fine, and the sea calm, it is 

 very amusing to watch the rapid expansions and 

 retractions of their many coloured tentacula, 

 while they are moving in search of food : to ob- 

 serve the quickness with which they seize on 

 whatever prey comes within their reach, and to 

 notice the suddenness with which they collapse 

 into a round contracted mass, on receiving the 

 slightest injury. 



Yet these animals are not of necessity con- 

 fined to the particular spots where we see them 

 fixed ; for they are capable, when disturbed, of 

 seeking, by a slow progressive motion, a more 



