The Intestines. 229 



tudinal and the circular muscular coats. The latter pre- 

 sides over the movements of the intestine, but both are 

 governed by branches from the solar plexus, which itself 

 is controlled by the splanchnics and the right pneumo- 

 gastric. The action of the fibres of the latter is, when irri- 

 tated, to affect the activity of Auerbach's plexus so as to 

 stimulate the movement of the intestine, while the former, 

 i.e., the splanchnic, is the great vasomotor controller of all 

 the abdominal viscera. This nerve (the splanchnic) 

 contains, in addition, sensory fibres for the intes- 

 tine as well as inhibitory fibres, i.e., fibres that lessen or 

 inhibit the intestinal movement. Normally, the pre- 

 sence of the usual intestinal contents stimulates 

 Auerbach's plexus and the unconscious peristaltic 

 movements of the bowel result. Should, however, 

 any irritating substance be present, the afferent or sen- 

 sory fibres of the sympathetic convey the impression up 

 to the solar plexus, and the efferent fibres, which run 

 from the pneumogastric filaments in the solar plexus to 

 Auerbach's plexus in the intestinal wall, excite increased 

 peristaltic movements, but, if the irritation be more mark- 

 ed, the afferent nerves carry the impression past the solar 

 plexus and onwards to the cerebrum and the effect of this 

 disturbance of the sensory fibres is appreciated as pain, as 

 in colic. Further, should the irritation be still more 

 pronounced, as in severe inflammation, the local centre will 

 be overstimulated and a paralytic condition of the intes- 

 tinal muscles result, and, inasmuch as the paralyzed mus- 

 cles will offer imperfect resistance to the action of the intes- 

 tinal gases, meteorism, or gaseous distention of the bowel 

 occurs. The sensory fibres of the splanchnic nerve may 

 be affected in lead poisoning, in which condition the pain 

 is referred to the terminations of these sensory fibres in 

 the intestine, and colic is experienced, whilst reflex dis- 



