NERVE ENDINGS, STOMACH AND SMALL INTESTINE 559 
As is also true of the skeins and end nets in the stomach of the 
cat, these intestinal endings of the dog are confined in all. the 
preparations studied to the outer or longitudinal muscle coat and 
to the adjacent connective tissue of the serous coat. All three 
types of ending are thus so placed that they would doubtless be 
directly affected by the contractions or distentions of the smooth 
muscle tunic within which the majority of them lie. As has been 
pointed out above, stimuli arising in this manner are, in the opin- 
ion of the physiologists quoted, the source of most of the sensa- 
tions, including pain, associated with the alimentary canal. 
SUMMARY 
1. Terminal structures in the form of, 1) skeins and, 2) nets, 
both composed of fine fibrils with numerous varicosities, occur in 
the longitudinal muscle coat of the cardiac stomach of the cat. 
A few are present in the serous coat. These endings are con- 
nected with unmyelinated, varicose nerve fibers, the source of 
which has not been determined. 
2. Terminal structures in the form of tufts of exceedingly deli- 
cate fibrils exhibiting more plainly differentiated varicosities in 
great abundance occur in the longitudinal muscle coat of the small 
intestine of the dog, and also to some extent in the subperitoneal 
connective tissue. These end tufts terminate fine non-medul- 
lated nerve fibers which appear of smaller caliber than the motor 
fibers supplying the smooth muscle cells. They have been traced 
centrally into the myenteric plexus. 
3. Structurally these endings conform to the sensory rather 
than to the motor type of nerve terminations. Their presence 
in the muscular coat, but not in the mucosa or submucosa, is 
consistent with the results of recent physiological experimenta- 
tion on the sensibility of the alimentary canal. 
