STOMACH AXD IXTESTIXE. 



777 



portion of the tube which forms the stomach turns over on its right 

 side, so that the border, which is connected to the vertebral cohminby 

 the membranous fold (or true mesogastrium) comes to be turned to the 

 left, — the position of the tube being still vertical, like the stomach of 

 some animals. By degrees it becomes more dilated, chiefly on what is 

 now the left border but subsequently becomes the great curvature, and 

 assumes first an oblique and finally a transverse position, carrying with 



Ficr. 578. 



K'fr^ 



Fig. f'78. — Outline of the Form ,and Position of the Alimentary Canal in 

 Successive Stages of its Development. 



A, alimentary canal, &c., in an emln-yo of five weeks ; B, at eight weeks ; C, at ten 

 ■weeks ; D, at twelve weeks ; I, tbe primitive lungs connected with tlie pharynx ; s, the 

 .stomach ; d, duodenum ; /, the small intestine ; i', the large ; c, the ciecum and vermi- 

 form appendage ; r, the rectum ; c /, in A, the cloaca ; a, in B, the anus distinct from 

 s /, the sinus uro-genitalis ; r, the yolk-sac ; v i, the vitello-intestiual duct ; u, the 

 urinary bladder and urachus leading to the allantois ; g, the genital ducts. In B, and 

 0, the thickness of the colon is erroneously represented as greater than that of the 

 ileum. 



it the mesogastrium, from which the great omentum is afterwards pro- 

 duced. A slight indication of the pylorus is seen at the third month. 

 Upon the surface of the part of the canal which immediately suc- 

 ceeds the stomach, and which forms the duodenum, the rudiments 

 of the liver, pancreas, and spleen are simultaneously deposited, in the 

 manner to be stated in the description of the development of these 

 organs. 



The place of transition from the small to the large intestine, which 

 is soon indicated by the protrusion of the cfECum, is at a point just 

 below the apex or middle of the simple loop already mentioned, as 

 accompanying the first elongation of the tubular gut. As the small 

 intestine grows, the part below the duodenum forms a coil which at 

 first lies in the commencing umbilical cord, but retires again into the 

 abdomen about the twelfth week ; aftei'wards it continues to elongate, 

 and its convolutions become more and more numerous. 



