FIRST BOOK OF ZOOLOGY. 



way, the dried point of the grass probably striking the head, 

 and then glancing off, and entering between the head and 

 the thorax. 



86. In studying the early stages of the mosquito, it was 

 found that at the outset the animal breathed air through an 

 opening in the hinder part of the body ; that soon after this 

 the opening closed, and air was taken in by two openings on 

 the back, but in no case did the insect breathe through its 

 mouth. In the perfect insect, as well as in most larvse, there 

 are little openings along the sides of the body. These little 

 openings communicate with tubes which branch, and sub- 

 divide again and again, sending their little air-twigs into 

 every part of the body, even into the legs and the veins of 

 the wings. These little tubes represent the lungs of an in- 

 sect. They necessarily render the body very light besides. 



w t 



m s h 



FIG. 90. INSECT SHOWING THE SPIRACLES. Grasshopper with the wings and two hinder pairs 

 of legs removed to show spiracles, or openings in the sides of the body which commu- 

 nicate with the air-tubes within the body : u\ showing where the wings were attached ; 

 h and m, where hind and middle legs were attached ; s, spiracle on thorax ; , tympanum. 



In large insects like the grasshopper the minute openings 

 in the sides of the body can be plainly seen without the aid 

 of a glass. The segments of the abdomen have each a little 



