THE M rONOMIC NERVO M 385 



ergotoxine, however, a reversed effecl is observed; namely, inhibition 

 instead of augmentation. By taking advantage of this fact, Dale 



□ able to demonstrate in the hypogastric nerves inhibitory fibers to 

 the uterus, and Elliotl has demonstrated the inhibitory action i 

 nephrine on the muscles of the ureter in the 'l"'-r. Inhibitory fibers I 

 also been discovered by these methods in the great splanchnic nerves, in 

 the nerve roots supplying the kidney, and in the cervical sympathi 

 supplying the blood vessels of the mucous membrane of the mouth, i 

 thai is, in nerve trunks which previously were believed to contain only 

 augmentory tihers. The accompanying diagram from Jackson will give 

 an idea of the currently accepted views concerning the distribution of 

 augmentory and inhibitory fibers. * Fig. 233. 



THE AFFERENT FIBERS OF THE AUTONOMIC SYSTEM 



It has long been known that the exposed viscera are remarkably ins< 

 sitive. This experience is in accord with the observation that the supply 

 of afferent fibers to the viscera is relatively very small. In the hypo- 

 gastric and probably in the great splanchnic nerve, Langley computes 

 that only about one-tenth of the medullated fibers are afferent. At the 

 two ends of the alimentary canal, where cooperative i - betwi 



the somatic musculature and the viscera are of import iter 



number of afferent fibers are found in the autonomic ner 

 ample, in the pelvic nerve about one-third of the fibers are afferent, and. 

 as Ave have frequently seen, the vagi contain large numbers of them 

 coming from the lungs, stomach, and no doubt from other viscera. 



The afferent visceral fibers, as above stated, arise like thos the 



voluntary system, from the ganglion cells of the posterior roots. They 

 travel in company with the connector fibers through the white ramus 

 communicans, so that the stimulation of the central end of one of t ; 

 may cause reflex rise in blood pressure and other movemenl 



It is found that, after opening the abdominal cavity under local 

 anesthesia, cutting and suturing of the viscera may be continued without 

 causing any pain. When the viscera are inflamed, how. ind on 



certain conditions of stimulation, such as the distention • bile du 



with biliary calculi, or the violent contraction of the inti ici- 



ating pain may be evoked. This pain is frequently not localized in the 

 viscera, but is referred to certain parts of the SU1 E the 



it has been shown by Mackenzie and by Head that it • the 



area of skin which is supplied witl >ry nerves by the same segment 



as that to which the afferent autonomic til- ticular via 



run. It lias further been shown that vascular 



