96 



FIRST LESSONS IN ZOOLOGY. 



the under side of the uppermost of the fore-wings a sort of 

 file which rubs over a resonant surface, like a drum's head. 

 The file may be likened to the bow, and the drum-like 

 space to the body of the violin. Thus, most grasshoppers 

 are fiddlers, and during the summer, both by day and night, 

 the air resounds with the music of these primitive violin- 

 ists. This noise may add to our pleasure or become tedi- 

 ous and disagreeable. This makes little difference, for in- 

 sect music is all-important. It is the cricket's love-call, 



F 



FIG. 102. &', cells at end of trachea, where aeration of the tissues takes place; 



F, a fat-cell. 



and were crickets, etc., deaf and dumb, we are safe in say- 

 ing the breed would soon run out. 



We have seen that the lobster breathes by gills on the 

 outside of the body. With insects all this is changed. 

 They do not, however, draw in the air through their 

 mouth, but inhale it through minute openings on tbe side 

 of the chest and hind body. There are in the locust ten 

 pairs of these holes or " spiracles;" two pairs on the tho- 

 rax, and the remainder on the sides of the abdomen. They 

 are hard to find at first, but may be detected with the aid 

 of Fig. 98, where they are distinctly pointed out. The 

 air enters these holes, and is carried all over the body by 

 air-tubes, which end in minute air-cells (Fig. 102), where 

 the aeration of the surrounding tissues takes place. 



