144 



THE COCKROACH : 



sides of the body; the Cockroach, in addition to these, possesses 

 smaller longitudinal vessels, which lie close to the middle line, 

 on either side of the nerve-cord.* The ultimate branches form 

 an intricate network of extremely delicate tubes, which pene- 

 trates or overlies every tissue. 



Fig. 77. Tracheal System of Cockroach. Side view of head seen from without, 

 introducing the chief branches of the left half. X 15. 



* The longitudinal air-tubes are characteristic of the more specialised Tracheata. 

 In Araneidre, many Julidre, and Peripatus each spiracle has a separate t radical 

 system of its own. 



