Htp* 
The Life Processes of the Individual 
149 
flow of blood. The posterior end of the heart is closed 
but on the anterior end it is continued in a long tube (aorta, 
Ao) extending in various convolutions and arches through 
Fig. 78. — Longitudinal median vertical section of body of worker, showing nervous system, tracheal 
system, dorsal and ventral diaphragms and dorsal blood vessel. 
