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seen two openings with irregular contours. The one to the right — 
the larger — is the lumen of the ductus communis choledochus. The 
other is the lumen of the duct of Wırsung. Surrounding these lumina 
so as to embrace them, are bundles of smooth muscle. The figure 
shows one muscle bundle traversing the space between the two lumina 
and connected above and below with other muscle bundles in such 
manner as to form a double ring of muscle embracing the two ducts. 
The ring of muscle here shown corresponds to the muscle ring about 
the mouth of common bile-duct found in macerated specimens. Ex- 
amination of second set of serial sections in this region, showed the 
muscle ring embracing both the common bile-duct and the duct of 
WIRSUNG, but in this instance no distinct bundle of muscle could be 
seen traversing the space between the two lumina. Apparently no one 
has suspected up to the present time, the existence of this double 
muscle ring embracing the mouths of the common bile-duct and the 
duct of WirsunG. 
On both sides of this double ring of muscle one can make out 
muscle bundles cut transversely. In two or three places the bundles 
of the muscle ring are connected with these transversely cut fibres. 
These bundles (transversly cut) as well as others seen below lying on 
the inner surface of the inner circular muscular coat of the intestine, 
represent sections of those lateral fasciculi which in macerated spe- 
cimens are seen to have origin in the ring of muscle about the mouth 
of the common bile-duct and to bend around and run down in the 
duodenum, X. Other sections show these lateral fasciculi terminating 
by mixing superficially with the muscle fibres of the inner circular 
muscular coat. It is to be noted that the lumen of the common bile- 
duct is partially filled with folds of mucous membrane at this point. 
Fig. 5 is taken at a point further away from the mouth of the 
common bile-duct. In this section only one lumen is present, that of 
the common bile-duct. The lateral fasciculi which have origin in the 
ring of muscle about the mouth of the common bile-duct, and which 
bend around and run down the duodenum are, however, shown here 
quite well. The mass of muscle to which the lateral fasciculus runs 
(on the left) probably represents the point d’appui noted in the 
macerated specimens. 
Fig. 6 is taken at a point about midway in the course of the 
common bile-duct through the intestinal wall. The structures show 
the division of the inner circular muscular coat of the intestine. Part 
passes over and part passes under the common bile-duct. Where the 
