384 



RICHARD E. SCAMMON 



middle part of the duct is also directed sharply ventrally along 

 with the change in position of the segment of the gut which it 

 joins. This ventral curve appears in embryos of 18 to 20 mm. 

 and is at first a gradual one but becomes sharper and more pro- 



A 



J) chol. 



J), pane. 



D.chol. 



D-pa>"c. 



Fig. 30 A series of transverse sections of Acanthias embryos of different ages 

 at the level of the ostium of the ductus choledochus. A, embryo 15.5 mm. long 

 (S.C. 1) ; B, embryo 20.6 mm. long (H.E.C. 1494) ; C, embryo 32.2 mm. long (II. E.G. 

 1662); D, embryo 180 mm. long (S.C. 51) all except D X 28; D X 8. D.chol., 

 ductus choledochus; D.panc. , pancreatic duct; D.vil., vitelline duct; Duo., duo- 

 denum; Pane, pancreas; St., stomach. 



nounced in older embryos. In .the course of this curve the duct is 

 also pushed to the right by the vitelline vein which lies beside it. 

 Minor short flexures appear in later stages near the anterior and 

 posterior ends of the duct and in its duodenal curve as well. 

 They are not constant in position, shape or number. The duct 



