THE EMBRYO. 



1205 



now becomes smaller than the right ; but up to the end of foetal life the liver 

 remains relatively larger than in the adult. 



The pancreas is also an early formation, being far advanced in the second 



Stomach 

 Greater curvatur> 



Posterior lamella of greater amentum 

 Transverse colon 



Greater amentum 



Diaphragm 

 Liver 



Lesser omentum 



Pancreas 



Part of omentum enclosing pancreas 



Transverse mesocolon 



Duodenum 



Mesentery 

 Small intestine 



FIG. 770. Development of bursa omentalis. Infantile stage, (ireat omentum covers the intestines and has 

 fused with the transverse mesocolon. Pancreas is free from peritoneum posteriorly. (Hertwig.) 



month. It originates as a hollow projection from the hypoblast of the dorsal wall 

 of the duodenum (Figs. 760 and 761), opposite the hepatic diverticula, which, as 

 we have already seen, spring from its ventral wall. This hollow process grows 



Minnlibular arch. 

 Hyoid arch. 



Third arch. 

 Fourth arch. 



FIG. 771. The floor of the pharynx of a human embryo about fifteen days old; X 50. (From His.) 



between the two layers of the dorsal mesentery and sends out offshoots, which 

 branch abundantly and form a complicated tubular gland. As torsion of the 

 stomach takes place, the pancreas assumes a transverse position and becomes fixed 



Tuberculum impar 

 (papillary part of tongue). 



Entrance to larynx 



Posterior part of tongue, 

 i 



Furcula. 



,Mandibular arch. 



-Hyoid arch. 



Third arch. 

 ^Fourth arch. 



--Lung. 

 FIG. 772. The floor of the pharynx of a human embryo about twenty-three days old; X 30. (From His.) 



across the dorsal wall of the abdomen, the posterior layer of its mesentery under- 

 going absorption. Its duct ultimately opens into the duodenum together with the 

 common bile-duct. 



The spleen, on the other hand, is of mesoblastic origin, for there is never any 



