REFLEX ACTIONS. MOVEMENTS OF STOMACH. 303 



part of the oesophagus in the neck is made to contract peristaltically from 

 above downwards, by irritation of the roots of the first three Cervical nerves, 

 and of the cervical portion of the Sympathetic, through which last the former 

 evidently operate. The thoracic portion of the oesophagus is made to con- 

 tract, by irritation of the lowest Sympathetic ganglion of the neck, and of 

 the higher thoracic ganglia, and also of the roots of the lower Cervical spinal 

 nerves. Muscular contractions of the stomach are produced, by irritation of 

 the roots of the 4th, 5th, 6th, and 7th Cervical nerves, and of the first tho- 

 racic in the rabbit ; so that a distinct furrow is evident between the cardiac 

 and pyloric portion of the viscus ; and the lower the nerve irritated, the 

 nearer the pylorus do the contractions extend. Irritation of the first thoracic 

 ganglion of the Sympathetic produces the same effect. Contractions of the 

 intestinal tube, varying in place according to the part of the Spinal Cord ex- 

 perimented on, may be excited by irritation of the roots of the dorsal, lumbar, 

 and sacral nerves, and of the trigeminus ; and similar effects are produced by 

 irritation of the lower part of the thoracic portion, of the lumbar, and of the 

 sacral portions of the Sympathetic, also of the splanchnic, and of the gastric 

 plexus. 



389. From these facts it is evident, that the movements of the Intestinal 

 tube may be influenced by the Spinal Cord ; and that what is commonly 

 termed the Sympathetic nerve, is the channel of that influence, by the fibres 

 which it derives from the Spinal system. But it by no means thence follows, 

 that the ordinary peristaltic actions of the muscles in question are dependent 

 on a stimulus reflected through the spinal cord, rather than on one directly 

 applied to themselves. It is clear that, although these movements are of the 

 first importance to the welfare of the system, such means of sustaining them 

 are feeble, compared to those which we find provided for the maintenance of 

 the distinctly-reflex actions of deglutition, respiration, &c. The difficulty 

 with which any evidence can be obtained of the connection, is a sufficient 

 proof of this. On the other hand, we do know that these peristaltic move- 

 ments are influenced by particular states of mind, or by conditions of the bodily 

 system ; and the connection just traced satisfactorily accounts for this, and is 

 itself sufficiently explained. The intestinal tube, then, from the stomach to 

 the rectum is not dependent upon the Spinal cord for its contractility, but is 

 enabled to propel its contents by its own inherent powers ; still we find that 

 here, as in other instances, the nervous centres exert a general control over 

 even the Organic functions, doubtless for the purpose of harmonizing them 

 with each other, and with the conditions of the organs of Animal life. 



390. The Muscular Coat of the Bladder appears, like that of the Intestinal 

 tube, to be ordinarily excited to contraction, rather by direct stimulation than 

 by the agency of the Spinal nerves. It is not, however, altogether removed 

 from the influence of the Spinal Cord ; for the experiments of Valentin have 

 shown that a connection exists, as in the former case, through the Sympathetic 

 nerve, affecting not only the bladder but also the ureters. That physiologist 

 states, that a very distinct and powerful peristaltic action of the ureter, pro- 

 ceeding from the kidneys to the bladder, may be produced, by irritating the 

 abdominal ganglia of the Sympathetic, or the roots of the superior abdominal 

 Spinal nerves ; and that strong contractions of the bladder are excited, by irri- 

 tation of the inferior portion of the abdominal Sympathetic, but especially of 

 its sacral portion, and of the roots of the middle and inferior nerves of the 

 Spine. In these, as in former cases, no effect is produced by irritation of the 

 Spinal Nerves, unless the portion of the Sympathetic connected with the par- 

 ticular organ be entire. 



391. On examining the outlets by which the excretions are voided, we find 

 that they are placed, like the entrances, under the guardianship of the Spinal 

 Cord; subject, however, to some control on the part of the Will. In the 



