THE ORGANS OF CIRCULATION AND RESPIRATION. 



145 



Fig. 78. Tracheal System of Cockroach. Top and front of head seen from 



without, x 15. 



Fig. 79. Tracheal System of Cockroach. Back of head, seen from the front, the 

 fore half being removed. X 15. The letters A J indicate corresponding 

 branches in figs. 77, 78, and 79. 



