THE COCKROACH. 



357 



The large tracheie which take their origin from these 

 stigmata immediately divide and give off dorsal and ventral 

 branches; the former unite in a series of arches on each 

 side of the heart, while, on the ventral side, the branches 

 are connected by trunks which run parallel with the abdominal 

 gano-lia. Large tracheae pass from the anterior thoracic stigma 

 through the neck into the head, and, in the abdomen, the vis- 

 cera receive an abundant supply of air-tubes. 



9 



Fig. 100.— Blatta orkntcdis.—C. the brain with the antennary (a) and optic (b) 

 nerves ; c, e, /; g, A, ^tomato-gastric nerves. B^ the anterior end of the gullet. 

 A, the crop. Z>, the gizzard. 



The lobes of the corpus adiposum are also plentifully 

 supplied with trachece, while fine trunks enter the substance 

 of the ganglia and nerves and there ramify. Tracheae accom- 

 pany the nervures of the wings and are abundantly distrib- 

 uted to the muscles. 



The nervous system consists of the supra-resophageal 

 ganglia (Fig. 100, A)^ commonly termed the brain, united by 



