THE DIGESTIVE SYSTEM 



237 



derm unite in the median plane to form the tubular heart and the meso- 

 cardial membranes in which the embryonic heart is suspended. In the 

 abdominal part of the coelom the splanchnic layers of mesoderm unite 



dorsal mesoderm 



intermediate mesoderm 

 lateral mesoderm 



Fig. 221. Schematic diagrams of cross sections at various stages to show the 

 establishment of the coelom and mesenteries. (From Patten's "Embryology of the 

 Chick.") 



above and below the alimentary canal to form dorsal and ventral mesen- 

 teries. (Fig. 221) The dorsal mesentery persists throughout life, but the 

 greater part of the ventral mesentery disappears in ontogenesis. Only 

 the anterior portion which connects stomach, liver and ventral body- wall 



