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 he 
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 
he 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 antennee. Whoever has watched the 
antenna 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 
