AMONG THE INSECTS. 8 1 



ear, it should be said, has been found on the abdomen 

 of the cockroach. 



Having learned how easy it is to crush a fly or a 

 mosquito, it is well to inquire about the bones of these 

 animals. A bird or a chicken can not be so com- 

 pletely pulverized by pressing upon it. After the flesh, 

 or soft part of the chicken is removed, the bones 

 hard and tough remain. After the horny case that 

 incloses the insect is broken, the soft parts, or flesh, 

 are found within. The crust that envelops it, is the fly's 

 skeleton. The fly wears its skeleton on the outside of 

 its flesh ; the chicken wears its skeleton on the inside. 



The fly digests its food much more simply than 

 does the chicken. Through 

 its body runs a single tube 

 which is enlarged in one 

 place for a gizzard armed 

 with horny teeth ; and in 

 anotner place it swells into a 

 sac for 'a stomach. No red 



Fig. 9. Breathing Tubes of Ply. 



blood appears to flow when 



the insect is wounded or crushed. The blood of insects 



is white or colorless. 



Another peculiarity of the fly, and of its fellow in- 

 sects, is the way in which they breathe. They do not 

 draw the air through the mouth into lungs, as we do. 

 They have no lungs. In the crust which covers their 

 bodies are holes, or spiracles (sp\ that open into tubes. 

 These tubes, swelling into air-sacs here and there, 

 branch into every part of the body. Alongside of 

 them lie the blood-vessels which receive air from the 

 tubes, as our blood takes air from our lungs. 



L. C.-6. 



