TOUCH. 383 



those instruments which are more particularly 

 intended as organs of touch, should possess this 

 property. 



It will not be necessary to enter into a minute 

 description of these organs, because they have, 

 for the most part, been already noticed as in- 

 struments of motion or prehension ; for the sense 

 of touch is in general exercised more particularly 

 by the same parts which perform this latter 

 function. Thus the tentacula of the various 

 tribes of Polypi, of Actiniae, and of Annelida, 

 are organs both of prehension and of touch. 

 The tubular feet of the Asterias and Echinus 

 are subservient both to the sense of touch, and 

 to the faculty of progressive motion. The feet 

 of Insects and of Crustacea are well calculated, 

 indeed, by their jointed structure, for being 

 applied to the surfaces, and ditferent sides of 

 bodies ; but they are scarcely ever employed 

 in this capacity ; being superseded by the palpi, 

 which are situated near the mouth. When 

 insects are walking, the palpi are incessantly 

 applied to the surface on which they advance, 

 as if these organs were especially employed to 

 feel their way. There can be little doubt, how- 

 ever, that, in most insects, the principal organs 

 of touch are the A7Uenn<s\ also denominated, from 

 their supposed office, the feelers.'^ 



Some idea of the great variety in the forms of 



* The German name for them, fiihlhorner, or the feeling 

 horns, is founded on the same notion. 



