APPARATUS OF EESPIKATION. 



71 



This canal or tube is formed of a series of small cartila- 

 ginous bands, incomplete behind. It is lined by a mucous 



Fig. 48. Kespiratory Apparatus of the Insect (la Nepe).* 



membrane, which is of the same nature as the mucous mem- 

 brane of the mouth and nostrils, and is continuous with 



* o, the head ; 6, base of the feet of the first pair ; c, first ring of the 

 thorax ; d, base of the wings ; e, base of the feet of the second pair ; f, stig- 

 mata; g, tracheae; A, aerian vesicles. 



