256 SENSES OP INSECTS. 



of a boot or shoe, so insects feel sufficiently through the 

 crust of their legs for all purposes of motion. Besides, 

 the points that are covered by a thinner cuticle are often 

 numerous; so that touch, at least in a passive sense, may 

 be pretty generally dispersed over their bodies ; but ac- 

 tive or exploring touch is confined to a few organs, as 

 the antenna^ the palpi, and the arms. The two last I 

 shall now discuss. 



Various opinions have been started concerning the use 

 of the palpi. Bonsdorf thought that they were organs 

 of smell ; Knoch, that this sense was confined to the 

 maxillary ones, and that the labial ones were appro- 

 priated to taste* : but the most early idea, and that from 

 which they derive their present name of palpi (feelers}, is, 

 that they are organs of active touch , and this seems to me 

 the most correct and likely opinion. Cuvier, himself a 

 host, has embraced this side of the question b , and Leh- 

 mann also admits it c . The following observations tend 

 to confirm this opinion. The palpi of numerous insects 

 when they walk, are frequently, or rather without inter- 

 mission, applied to the surface on which they are moving 

 - this you may easily see by placing one upon your 

 hand; which seems to indicate that they arefeelers. In 

 the Araneida they are used as legs ; and by the males 

 at least, as exciting if they be not really genital organs d . 

 In the Scdrpionidte they answer the purpose of hands : 

 besides being usually much shorter than antennae, they 



a Lehmann De Sens. Extern. Anim. Exsang. De Olfactu. 



b Cuv. Anat. Comp. ii. 675. Ubi supr. 



d Marcel de Serres says they are connected with testes seated in 

 the trunk (Mem. du Mus. 1819. 95); but Treviranus denies this 

 (Arachnid. 30. t. iv./. 33). 



