INFLUENCE OF NERVES ON THE INTESTINE. 319 



5. The continued application of strong stimuli causes complete 

 paralysis of the intestine, such as occurs after violent peritonitis, or 

 inflammation of the musculature or mucous coat in man. In this con- 

 dition, the intestine is greatly distended, as the paralysed musculature 

 does not offer sufficient resistance to the intestinal gases which are 

 expanded by the heat. This constitutes the condition of meteorism. 



Influence of Nerves. With regard to the nerves of the intestine, 

 stimulation of the vagus increases the movements (of the small intes- 

 tine), either by conducting impressions to the plexus niyentericus, or 

 by causing contraction of the stomach, which stimulates the intestine in 

 a purely mechanical manner (Braam-Houckgeest). The splanchnic is 

 (1) the inhibitory nerve of the small intestine (Pfliiger), but only as long 

 as the circulation in the intestinal blood-vessels is undisturbed, and the 

 blood in the capillaries does not become venous (Sigm. Mayer, and 

 von Basch) ; when the latter condition occurs, stimulation of the 

 splanchnic increases the peristalsis. If arterial blood be freely sup- 

 plied, the inhibitory action continues for some time (0. Nasse). Stimu- 

 lation of the origin of the splanchnics, of the spinal cord in the dorsal 

 region (under the same conditions), and even when general tetanus has 

 been produced by the administration of strychnia, causes an inhibitory 

 effect. 0. Nasse concludes from these experiments that the splanchnic 

 contains (2) inhibitory fibres which are easily exhausted by a venous 

 condition of the blood, and also motor fibres which remain excitable for 

 a longer time, because after death, stimulation of the splanchnics always 

 causes peristalsis, just like stimulation of the vagus. (3) The splanch- 

 nic is also the vaso-motor nerve of all the intestinal blood-vessels, so that 

 it governs the largest vascular area in the body. When it is stimu- 

 lated, all the vessels of the intestine, which contain muscular fibres in 

 their walls, contract ; when it is divided, they dilate. In the latter 

 case, a large amount of blood accumulates within the blood-vessels of 

 the abdomen, so that there is anaemia of the other parts of the body, 

 which may be so great as to cause death owing to the deficient supply 

 of blood to the medulla oblongata. (4) The splanchnic is the sensory 

 nerve of the intestine, and as such, under certain circumstances, it may 

 give rise to extremely painful sensations. 



As stimulation of the splanchnic contracts the blood-vessels, von Basch has 

 raised the question, whether the intestine does not come to rest, owing to the want 

 of the blood, which acts as a stimulus. But, when a weak stimulus is applied 

 to the splanchnic, the intestine ceases to move before the blood-vessels contract 

 (van Braam-Houckgeest) ; it would therefore seem that the stimulation diminishes 

 the excitability of the plexus myentericus. 



According to Engelmann and v. Brakel, the peristaltic movement is chiefly pro- 

 pagated by direct muscular conduction, as in the heart and ureter, without the 

 intervention of any nerve-fibres. 



