214 
arising from the outer longitudinal muscle coat and running up on the 
common bile-duct can, however, be demonstrated in this specimen. 
The Cystic Duct of Man. 
In consideration of the apparent diversity of opinion as to the 
presence of a sphincter muscle in the cystic duct or at the neck of 
the gall-bladder, the results of our work on the cystic duct of man 
will be given. 
Macerations of the cystic duct in a mixture of nitric acid, glycerine 
and water showed the arrangement of smooth muscle to be plexiform. 
Longitudinal celloidin sections of the cystic duct demonstrated smooth 
muscle running in three directions, viz. transverse, longitudinal, and 
diagonal. The transverse bundles are most numerous; the longitudinal 
and diagonal bundles are about equal in number. In that portion of 
the cystic duct nearest the neck of the 
gall-bladder, the amount of muscle is con- 
siderable, but this gradually diminishes in 
amount as the common bile-duct is appro- 
ached. At the junction of the cystic, hepatic 
and common bile-duct the quantity of 
muscle present is very small. These sec- 
tions also show muscle fibres in those folds 
of the cystic duct which are known as the 
valves of Heister. The fact that muscle 
is present in these folds has been noted 
before by Mac ALISTER and he does not 
undertake to describe the course pursued 
by the muscle bundles. 
In a set of serial longitudinal sections 
of the entire human cystic duct, I have 
found the arrangement represented by the 
schema given in Fig. 17. It is based upon 
study of the serial sections, and shows: 
1) That the transverse muscle bundles 
of the cystic duct are not limited to the 
Fig. 17. The cystic duct of man, showing the 
Heisterian valve; also, a diagram of the musculature 
of the Heisterian valve. 
wall proper, but at the level of the valves of HEISTER also run around 
in the valve in a circular direction. It is just as if the wall of the 
duct had been invaginated at this level and as a res sult the circular 
muscle fibres were carried out into the fold thus formed. 
