48 The Form of Insects 



with its feelers, and trying the surface over which it 

 walks with its palps, can doubt that the creature 

 gets much information as to its surroundings from its 

 sense of touch. 



Org"ans of Smell. — But the feelers are the 

 principal seat of another sense of the highest im- 

 portance in the life of the insect. After lengthened 

 discussion and many researches, no doubt remains 

 that they contain organs of smell. Rods covered 

 with strongly-scented acids, when brought near 

 insects, cause the feelers to be moved with energy, 

 and subsequently to be cleaned by being drawn 

 through the mouth. On the other hand, carrion- 

 eating insects, deprived of their feelers, are unable 

 to find their favourite food. Microscopic examination 

 shows the minute structure of the smelling organs. 

 Certain parts of the feelers are covered with tiny pits 

 (fig. 33 j4) formed by inpushing of the skin, and 

 sometimes protected by pegs or teeth. The pits are 

 filled with fluid and contain rod-shaped cells in connec- 

 tion with large nerve-cells (fig. 29 C, 33 B, C, G, K) 

 whence fibrils lead the impressions to the main nerve 

 of the feeler, and so to the brain. It has been cal- 

 culated that 1300 of these smelling pits occur upon a 

 single segment of the feeler in a Hornet, and as many 

 as 13000, in the whole feeler. They are still more 

 numerous in those insects whose feelers are complex 

 in structure — serrate, branched, or feathered ; nearly 

 40,000 are present on each feeler of a male Cockchafer. 

 Organs of similar structure have been observed on the 

 palps of various insects, as well as on the abdominal 

 cercopods in Cockroaches, Crickets and Lacewing 

 flies (fig. 29 D). But experiments seem to show that 

 the feelers are pre-eminently the seat of the sense of 

 smell (2, 26). 



Organs of Taste. — It is a matter of common 



