TOUCH. 



345 



ture,* their incessant motion when the insect is 

 walking, and their constant employment in exa- 

 minins: the surfaces of all the bodies with which 



they come in contact, sufficiently point them out 

 as instruments of a very delicate sense of touch. 

 Organs of this kind were particularly necessary to 

 insects, since the horny nature of the integuments 

 of the greater number precludes them from impart- 

 ing any accurate perceptions of touch. 



It has been conjectured that the antennce of 

 insects are the organs of other senses besides that 

 of touch. If an insect be deprived of its antennae, 

 it either remains motionless, or if it attempt to walk 

 or fly, appears bewildered, and moves without any 



* The number of segments into which these organs are divided is 

 often very great. In the Gryllotalpa, or mole cricket, it amounts 

 to above 100. (Kidd, Phil. Trans, for 1825, p. 211.) This insect 

 has, besides the antennae on the head, two posterior or caudal an- 

 tennae, which are not jointed, excepting at their very com.mencement. 

 These are extremely sensible, and serve probably to give the animal 

 notice of the approach of any annoyance from behind, lb. p. 216. 



