THE DVODEXAL FOLD 



1003 



If the diagram (fig. 562), wliieh shows a transverse section of the abdomen at 

 the level of the foramen of Winslow, be examined, it will be seen that the posterior 

 layer of the gastro-heijatie omentum, the covering of the posterior wall of the 

 stomach, the right layer of the gastro-sijlcnic omentum, and the })eritf)n('um over 

 the pancreas, are all derived from this so-called lesser sac of the peritoneum. If 

 one could imagine the stomach to be once more brought back to its original median 

 position, some such a]>pearance as is shown in fig. (j()4 would be presented. 



Fig. (J05.— Intestine of MACRons pesk-illatl-s. 



COLON 



From this it will be seen that the gastro-splenic omentum, the coverings of the 

 stomach, and the gastro-hepatic omentum are all derived from the original meso- 

 gaster, the posterior attachment of which has been shifted considerably to the left. 

 The left margin of the foramen of Winslow will then be seen to be the free anterior 

 or ventral margin of this sim])le ])vimitive fold. 



The gastro-splenic omentum. — The spleen develops in the meso-gaster 



Fig. 606.— Duodenal Fold of Macropus penicillatus. 



j^osterior to the stomach, and the gastro-splenic omentum is V>ut a little altered jiart 

 of the original membrane. 



This relation of the spleen to the meso-gaster is very admirably demonstrated 

 in some animals (figs. oOS, 594, 595, and 001). 



The duodenal fold is to be seen in the bodies of nearly all mammals below 

 man. excluding those somewhat lower species in which the intestinal tube remains 

 still as a median loop (pages 993, 994). 



