THE MICROSCOPE AND INSECT LIFE 



the edge of each ridge is, as we can see if we magnify 

 it, rough like a file. This file-like ridge is rubbed 

 against a smooth ridge on the edge of the fore wing 

 and the result is the familiar note of the grasshopper. 



This insect also has ears, but they are not easy 

 to find unless they are pointed out to us. If we 

 examine a grasshopper we shall see that its body 

 is divided into three parts : a head, a solid portion 

 from which the wings and legs arise, the thorax and 

 a portion (the abdomen) made up of a number of 

 rings or segments. On the sides of the first of these 

 rings, counting from the forward end, we shall find 

 small depressions covered with membrane, these are 

 the ears. It is curious that although many of the 

 grasshoppers cannot give out a note, so far as human 

 ears can detect, they nearly all have ears; maybe 

 there is a grasshopper song which only grasshoppers 

 can hear. 



Very many other insects have sound organs, but 

 they are nearly all constructed on the same plan. 

 It may seem surprising that sounds can be produced 

 by these simple means. Sound is really caused by 

 waves in the air and these insect vocal organs set 

 up rapid sound waves, by their vibration. 



The microscopist should never be at a loss for 

 objects derived from the insect world : it is impos- 

 sible to walk without treading upon some six legged 

 wayfarer. The wing cases of beetles are often of 

 rare beauty, some on account of their sculpturing, 

 some because of a mantle of scales. 



In our greenhouse and garden we can find mealy 



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