TYPICAL INSECTS 



187 



chitin. It is the hardened epidermis of the insect. To per- 

 mit the insect knight to move in his coat of mail, it is made 

 in sections united by flexible bands similar to the jointed 

 mail of old ; and, as with human armor, so here the vulnerable 

 spot is between the plates at the flexible membranes. This 

 is where a wasp would insert her dagger. 



The abdomen of the grasshopper is divided into ten ring 

 segments, that fit together with 

 flexible joints. On each side of a 

 segment is a small pit or breath- 

 ing pore. These pores commu- 

 nicate with a complete system of 

 air-tubes that branch throughout 

 the body, even into the veins of 

 the wings. They are the lungr 

 of the insect. Observe a grass 

 hopper breathing. Note how the 

 abdomen expands and contracts 

 By a muscular exertion the air is 

 expelled, and the natural elasticity of the body- wall causes it 

 to expand and draw in the air. 



The end of the abdomen of the female grasshopper has a 

 forked appearance, on account of the projecting lobes. This 

 arrangement is the egg-placer, or ovipositor, with which the 

 female bores a hole in the ground and deposits her eggs in 

 the burrow. The male's abdomen is blunt and round. 



The fact that some insects, like the cricket, the grasshopper, 

 and others, possess a call or ' song" argues that there is a 

 receptive organ for the sound. The ears, or hearing organs, 

 of some insects have been located. The ear of the grass- 

 hopper may be found by hfting up the wings and looking at 



Fig. 4' . Breathing Pore of a 

 Cockroacli. 



'Photomicrograph, 



