THE PHYLUM ANNELIDA 



Afferent typhlosolar 

 vessel 



Dorsal vessel 



Dermal 



Parietal ^^ ^^> 

 vessel 



Dorso- intestinal 

 vessel 



Nephridium 



Commissural 5 

 vessel 



Nephridial 



vessel 



Lateral neural 

 vessel 



Fig. 14.8. Some details of the circula- 

 tory system of the earthworm. .-1, 

 diasfram of a cross section of the body 

 in the ree;ion of the stomach-intestine, 

 showing; the chief elements of the cir- 

 culatory system in a typical see;ment. 

 Nephridial blood supply is shown on 

 the right, nephridial drainage on the 

 left; arrows indicate direction of blood 

 flow. B, details of the circulatory sys- 

 tem in relation to a nephridium. 

 (Modified from A. W. Bell, 1947, 

 Turtox News, vol. 25, printed by per- 

 mission of General Biological Supply 

 House, Inc.) 



Ventral vessel 



Segmental 

 vessel 



'I Dermal and 

 I parietal vessels 



Commissural vessel 

 Afferent nephridial vessel 

 Efferent nephridial vessel 



Segmental vessel 

 (To body wall) 



Afferent neural vessel 

 Lateral neural vessel 



metabolic wastes. Special additional functions occur in specific organs: in the 

 capillary beds of the body wall, for example, oxygen diflfusing through the skin 

 is taken up by the blood, and carbon dioxide is lost to the surrounding air. 

 In the wall of the stomach-intestine the blood receives the absorbed products 

 of digestion. In the nephridia, although the functional details of these organs 

 are not completely understood, the capillary blood flow apparently carries 

 back into the general circulation salts reabsorbed by the cells of the nephrid- 

 ial tubules; we shall return to this point shortly. The complexity and eflficient 



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