NERVOUS INFLUENCES AFFECTING INTESTINAL MOVEMENTS. 287 



the usual amount of gases gives rise to the quiet peristaltic movement 

 of the healthy individual euperistalsis. 



All stimuli transmitted to the my enteric plexus increase peristalsis, 

 which finally may progress to violent movement, with rumbling in the 

 intestines (borborygmus), and may even cause involuntary discharge 

 of feces and spasmodic contraction of the intestinal musculature. This 

 condition, which corresponds to dyspnea, may be designated dysper- 

 istalsis. 



This condition may be caused (a) by interruption of the circulation in the 

 intestines, ft matters not whether anemia, as after compression of the aorta, or 

 venous hyperemia is thereby induced. The exciting agent here is the deficiency 

 of oxygen, or the excess of carbon dioxid. Even slighter circulatory disturbances 

 in the intestinal blood-vessels, as, for instance, venous stasis in connection with 

 abundant transfusion into the veins, whereby transitory overdistention of the 

 venous system, and therefore stasis in the portal system occurs, give rise to in- 

 creased peristalsis. This takes the form of noises and rumbling in the intestines, 

 together with involuntary defecation, if, in consequence of transfusion of hetero- 

 geneous blood, stasis becomes marked, as a result of thrombosis of the intestinal 

 blood-vessels. Landois explains in this way the irresistible inclination to stool 

 and the increased peristalsis that attend certain forms of cardiac weakness of acute 

 onset and sclerosis of the coronary arteries, in consequence of which the circulation 

 in the intestines suddenly ceases. A similar state of affairs is observed even under 

 normal conditions. Landois believed that the persistent pressure in constipated 

 individuals induces the evacuation that eventually takes place, as much by exciting 

 peristalsis through the venous stasis in the intestines as by mechanical pressure 

 upon the intestinal canal. Also the increased peristalsis that constantly attends 

 approaching death depends, undoubtedly, upon circulatory disturbances and thus 

 upon an alteration in the amount of gases in the blood in the intestines. The 

 same statement is applicable to the increased intestinal movement that attends 

 certain emotional disturbances, as, for instance, fear. Here the stimulation of 

 the brain passes through the medulla oblongata (containing the center for the 

 vasomotor nerves) to the intestinal nerves and causes circulatory disturbances in 

 the intestines (coincidently with pallor). Restoration of the normal circulatory 

 condition restores the intestines to quiet peristalsis. Salvioli caused blood to 

 flow artificially through excised pieces of intestine by means of cannulas intro- 

 duced into the blood-vessels, and found that blood rich in oxygen caused intestinal 

 rest, while interruption of the circulation caused contractions of the intestines. 

 B6kai was able to overcome the dysperistalsis induced by the introduction of 

 carbon dioxid into the intestines by introducing oxygen into the intestinal cavity. 



(6) Direct irritation of the intestine causes movement not only of the part 

 directly affected, but also of the neighboring part of the intestines, especially that 

 lying toward the pylorus. The cumulative effect of stimuli is shown here ; that is 

 feeble stimuli, which are too weak to excite movement when applied but once, 

 do so on persistent repetition, as exposure of the intestines to the air, in more 

 marked degree in the presence of carbon dioxid and chlorin, the introduction of 

 certain irritating substances into the intestine, marked distention of the intestinal 

 canal, especially with coincident difficulty in or obstruction to defecation (which 

 occurs frequently in human beings), or direct irritation of different kinds, also 

 inflammatory processes involving the intestine either from within or from without. 

 In this connection, the observation is of interest that induced currents applied 

 to a hernial sac containing intestine excite active peristalsis in the hernia. Local 

 irritation of a portion of the intestine with a tetanizing induced current causes 

 a circular constriction, which advances especially toward the stomach when the 

 current is of considerable strength. The shortening of the longitudinal fibers that 

 are stimulated at the same time extends in both directions. 



With increasing temperature intestinal rest first results from irritation of the 

 splanchnic nerves; when the temperature reaches 43 C. intestinal movement is 

 resumed. 



All persistent stimuli of moderate strength cause cessation of dys- 

 peristaltic intestinal movement from overstimulation. This condition 

 may be designated intestinal exhaustion or intestinal paresis. 



