OF INSECTS. 181 



Touch is the sense most generally diffused over 

 the bodies of the higher animals., and it seems equally 

 dispersed among insects ; but the hard covering of 

 the latter must often render it very obtuse, except in 

 particular places. In the soft bodies of many larvae, 

 it is true, the skin is so delicate that it may well be 

 susceptible of the finest impressions, and capable of 

 transmitting the most vivid sensations; this power, 

 besides, is often greatly aided, in such cases, by the 

 hairs usually scattered over the surface. But though 

 the rigid covering may often produce comparative in- 

 sensibility, or merely give indication of the presence of 

 bodies, this sense is always so concentrated in certain 

 organs as to intimate the properties of material objects, 

 such as form, size, density, &c. The organs in which 

 it is most perfect are undoubtedly the palpi. Their 

 articulated structure adapts them for being closely 

 applied to bodies; the delicate membrane which 

 often covers their extremity is particularly fitted for 

 receiving impressions ; they are supplied with a con- 

 siderable nervous branch ; and they are observed to 

 be continually applied by the insect to the objects 

 with which it comes in contact. At the same time 

 there can be little doubt that the same function is 

 performed more or less perfectly by other parts, such 

 as the tarsi, the spiral proboscis of Lepidoptera, the 

 haustellum of Diptera, and in most tribes more espe- 

 cially by the antennae. Whoever has watched the 

 antennae of a hive-bee, an ant, or an ichneumon, 

 when engaged in any operation in which it is inte- 

 rested, will be surprised that ever it could be doubted 



