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mark of interrogation had its origin in part in some fibres of the 
muscle ring about the mouth of the common bile-duct. These fibres 
of origin, in this case, take the place of the muscle bundle which runs 
off at the pancreatic side of the muscle ring. The fasciculus on the 
pancreatic side of the muscle ring must terminate, after running for- 
ward a short distance, as described above in connexion with the ter- 
mination of the structure resembling a mark of interrogation — by 
passing under the fibres of the inner circular muscular coat of the 
intestine and blending with the fibres of the outer longitudinal coat. 
The fasciculus on the non-pancreatic side of the muscle ring, after 
running forward a short distance, curves slightly to the pancreatic 
side and finally terminates by mixing superficially with the fibres of 
the inner circular muscular coat of the intestine. The manner of ter- 
mination of these lateral fasciculi of the annulus about the mouth of 
the common bile-duct varies somewhat. They end a) by mixing super- 
ficially with the fibres of the inner circular muscular coat, b) by pas- 
sing more or less abruptly under the 
fibres of the inner circular muscular coat 
and becoming lost among the fibres of 
the outer longitudinal coat, and c) by a 
lateral fasciculus resembling the descrip- 
tion given either under a) or b). An 
illustration of this is given in Fig. 1. 
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Fig. 2. Macerated duodenal portion of the common bile-duct of dog. Part of the 
circular muscular coat of the intestine has been removed. % 4. 
After this preliminary study an incision was next made along the 
median line of the common bile-duct extending from the point A to 
the point R, Fig. 1. The fibres of the inner circular muscular coat 
of the intestine were then peeled off the bile-duct on both sides of the 
incision. The structure shown in Fig. 2 was revealed. Along the 
median line of the common bile-duct, a number of muscle fasciculi 
can be seen to arise. From this origin the muscle bundles run down 
and forward (towards the lower end of duodenum) over both sides of 
the common bile-duct. As the fibres on either side of the common 
bile-duct run forward, they unite, forming a relatively large bundle of 
muscle on each side of the bile-duct and in direct contact with it. 
The manner of termination of these bundles of muscle (running 
parallel with the bile-duct) varies somewhat. They end: — 
a) By running forward and around under the ampulla of VATER, 
