VADE MECUM. 9 



Insects, undpr uU their variotios of form, aro endowed with 

 antenna!, whicli is the name fjiven to those long or^'ans that 

 rise from each side of the liead ; but to what common nse, 

 or want of tlie insect kind, a provision so universal is sub- 

 servient, lia-s not yet been clearly ascertained. They liave 

 been regarded l)y some as organs of smell, and by others as 

 organs of tefft/i ; l)ut though they may be used occasionally 

 in exploring by touch, this is neither their general nor their 

 primary use, for the Qntennee of very gi'eat numbers never 

 are or can be employed for this puqjose. It is most ])robable 

 that they are the organs of a sense not perfectly analogous 

 to any of ours, but coming nearest to that of hairing, for 

 they certainly collect notices from the atmosphere. Tliis 

 unknown sense I/ehmann (who is the patron of the Iiypo- 

 thesis that makes them primarily tactus) calls u'croscepsy .' 



An extraordinary instance of irritability is exhibited l)y 

 the antliu, or instrument of suction of tlie Uutterfly. If this 

 organ, which the insect can roll up sjiirally like a watch- 

 spring, or extend in a straight direction, be cut ofi' as soon 

 as tlie animal is disclosed from the chrysalis, it will continue 

 to roll up or unroll Itself as if still attached to its head ; and 

 if, after having apparently cea,sed to move for three or four 

 hours, it be merely touched, it will again begin to move and 

 resume the same action. This is doubtless occa.sioned by 

 the peculiar structure of the antlia, which is composed of an 

 infinity of horny rings acted upon by muscles, rcore nume- 

 rous, prol)ably, than those which move the trmik of the 

 elephant. The motion only ceases when the muscles become 

 dry and rigid.t 



The Larvte of Butterflies are universally and emphatically 



• See Introduction to Entomology^ vol, iv. p. 235, 847, where 

 this subject 14 Inrgcly ULseussed. 



t Inti-udiiction to Entomology, vol. iv, p. 191, 192. 



