THE PERITONEUM. 



969 



The fore-gut contracts to form the oesophagus, which is very short (Fig. 587). 

 This gradually widens into a spindle-like dilatation indicating the stomach. The 



Ol? ,. /.'.I 



Stomach 



L; 



Jlid-gut 



FIG. 5S7. Schematic median section of a human embryo of fourth week. (After Dexter.) 

 small intestine is short and straight Avith a wide opening into the yolk-sac. Just 



ophagus 



Duodenal Loop 



Aorta 

 Chorda Dorsalis 



FIG. 588. Schematic median section of a human embryo of fifth or sixth week. (After Dexter.) 



below the stomach, the liver is budding out from the duodenum. This stage is 

 attained in the fourth week in the human embrvo. There are now five successive 



