42 . F. W. THYNG 



this outgrowth is from the left side of the primitive stomach is 

 evident, a relation evidenced in the adult by the reflection line 

 of the lieno-gastric ligament. The body (C) extends caudad 

 and ventrally, passing into the attenuated pars pylorica (P.py.) 

 which ends at a dilated portion of the duodenum {A.du.), the duo- 

 denal antrum of Retzius ('57). This, according to Lewis ('12) 

 always marks the position of the pylorus. The external surface 

 of the epithelium is for the most part smooth, but the internal 

 surface is indented by slight grooves representing the beginning 

 of the gastric pits. 



Intestine. Most of the small intestine and all of the large are 

 shown in plates 1 and 2 {Duo., Int.t., Int.cr., Int.r.). The duode- 

 nal division of the small intestine (Duo.) leading from the pyloric 

 end of the stomach passes transversely across the median line 

 from the left to right. Here it bends dorsally and receives the 

 duct of the dorsal pancreas (D.panc.d.), and the bile duct (D.chol.) 

 (text fig. 2) . The small intestine {hit.t.) then extends in a caudal 

 and ventral direction, a little to the right of the median line, into 

 the umbilical cord. In the umbilical cord it is bent twice in the 

 sagittal plane at approximately 90°. On the left side of the 

 second or cephalic bend {^1.2) it is continuous with the yolk-stalk 

 (D.vit.). The portion of the small intestine beyond the second 

 bend returns toward the body, cephalad of the part described, 

 and terminates at the caecum. 



The caecum forms a considerable dilatation and ends in the 

 vennifonn process (Pr.ver.) which projects ventrally and to the 

 left. 



The colon (Int.cr.) extends from the caecum, dorsally in the 

 median plane, crossing to the left of the duodenum. Opposite the 

 caudal extremity of the Wolffian body it turns caudally, and at an 

 arbitrary point becomes the rectum {Int.r.). It is evident that 

 the primitive U-shaped loop of intestine has undergone in this 

 embryo a rotation of approximately 180°. 



The epithelium of the duodenum a short distance caudad to the 

 bile duct presents on its left side one prominent diverticulum, 

 directed cephalad. Indications of similar outgrowths occur at 

 twelve other places along the portion of the small intestine within 



