THE FLATWORMS— PLATYHELMINTHES 



139 



Respiration is still not represented by any system, and there is direct 

 absorption of oxygen from the water by individual cells and the giving 

 off of carbon dioxide in the same way. 



Animals Without Backbones, Buchsbaum, The University of Chicago Press 

 Fig. 10.4. Excretory system of planaria. Note the extensive distribution of the flame 



cells that pick up the wastes. 



