554 F. W. CARPENTER 
gastric pain accompanying excessive inflation, gastric ulcers, 
and chronic obstruction is due to the mechanical stimulation of 
hypersensitive nerves or nerve endings in the muscularis or sub- 
mucosa by excessive distention or contraction.” 
Neurohistologists on the other hand, have been unable to 
verify by direct observation the presence, of sensory nerve end- 
ings in the smooth muscle of the abdominal viscera. As far as 
the writer is aware, no figures or descriptions of such structures 
are to be found in the text-books of neurology or general his- 
tology. Barker (’01), in his ‘Nervous System’ refers to a variety 
of pain characteristic enough to be designated as ‘smooth muscle 
pain,’ but leaves it to further investigation to determine the 
afferent elements among the numerous fibrils supplying smooth 
muscle membranes. Herrick (’15) recognizes the presence of gen- 
eral visceral receptors in visceral muscles, but points out that their 
endings have not been differentiated histologically from the 
simple terminations of the effector fibers. In their recently 
published “Text-book of Histology,’ Jordan and Ferguson (’16) 
describe only motor nerve endings in smooth muscle, although 
they, too, agree that “many of the nerve fibers in smooth muscle 
are undoubtedly of sensory function.’”’ In their chapter on the 
histology of the digestive system they give a diagram (from 
Kuntz, 713) illustrating the probable relationship of sympa- 
thetic neurones in the myenteric and submucous plexuses. 
This scheme shows sensory fibers distributed, outside the plex- 
uses, to the epithelium and tunica propria of the mucosa only; 
no afferent fibers are represented as ending in the muscular coat. 
In searching the special literature of the subject one meets, 
as haS been intimated, with exceedingly few references to nerve 
endings in smooth muscle that give evidence of being sensory. 
Practically all the endings described, such as the terminations 
in involuntary muscle figured by Huber and DeWitt (’98) are, 
by general agreement, regarded as motor in function. Schultz, 
in 1895, described multipolar nerve cells, which he believed to be © 
sensory elements, in the muscularis of the frog’s stomach. His 
observations, however, have not been confirmed, and Huber 
and DeWitt were doubtless right in regarding these as specialized 
