106 



ANATOMY OF AN ARTHROPOD. 



the mesenteron (Si). The hinder parts of the canal are com- 

 posed of the small and large intestines and rectum. The proxi- 

 mal end of the short small intestine or ileum is marked by the 

 attachment of a number of fine glandular tubes known as 

 Malpighimi tubules (Mc), which are probably excretory organs. 

 The colon or large intestine (Li) is wide and long, and termi- 

 nates in a sliort dilated terminal part, the rectum (B). At the 

 anterior end of the mesenteron will be seen seven convoluted 



^_- -a 



n 



Fm. 42.— i, Trachea, and ii, Slde-view of part of Abdomen, showing spiracle (5j?). 

 T, Tergum ; S, sternum ; a, spiral fibre ; i, inner coat ; r, outer coat. 



club-shaped diverticula called hepatic cava (H). (Five only are 

 represented in fig. 41.) 



The Hespiratonj S!/.<te)ii consists of a series of tubes containing 

 air. This can be easily demonstrated by plunging the opened 

 cockroach under water, when the tubes will be shown as silvery 

 threads, due to the air contained in them. These air-tubes or 

 frwheii' (fig. 42, i) commence at the spiracles and run to all 

 parts of .the body. ^\niL>n minutely examined the trachea^ 

 will be seen to be circumscribed by a dark spiral band {a). 

 Respiration takes place by these tubes, carrying the air to all 



