THE COCKROACH. 



357 



The larffe tracliene which take their orisrin 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 

 ganglia. 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. 



!:AI, 



r-<? 



Fig. 100.— Blatta orientalis.—C, the brain with the antennary (a) and optic ih) 

 nerves ; c, e, ./; gr, A, etomato-gastric nerves. B, the anterior end of the gullet. 

 A^ the crop. D, the gizzard. 



The lobes of the corpus adiposum are also plentifully 

 supplied with tracheas, while fine trunks enter the substance 

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

 pany the nervures of the wings and are abundantly distrib- 

 uted to the muscles. 



The nervous system consists of the supra-oesophageal 

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



