1016 DIGESTION 



be brought to bear either upon the muscle tissue or upon the nervous 

 tissue. The early experiments of Bayliss and Starling^ have led 

 strength to the first view, which is embodied in the so-called myogenic 

 theory of the origin of peristalsis, because it could be shown that the 

 application of nicotine does not destroy these movements. The 

 experiments of Cohnheim^ and Magnus,^ on the other hand, favor the 

 neurogenic theory, which holds that the nervous tissue is the recipient 

 element. Thus, it was found that isolated segments exhibited these 

 movements even after the removal of their mucosa and submucosa, 

 and that the separation of the inner and outer coats of muscle tissue 

 destroyed them only in that layer which was disconnected from the 

 plexus of Auerbach. In addition, Yanase^ has shown that the intes- 

 tines of the embryo rabbit and human fetus do not begin to move 

 until the aforesaid nervous elements have made their appearance. 



While this controversy seems to favor the neurogenic theory, it 

 may be best to confine ourselves for the present to the statement that 

 the peristaltic movements result in consequence of the stimulation of 

 the intestine by the fecal material and that they may arise in any one 

 of its different segments. The result is a diphasic wave, consisting of a 

 zone of constriction which is anteceded by a zone or relaxation. Con- 

 sequently, the peristaltic movement represents a true reflex response 

 which is made possible by the coordinated action of the local nervous 

 mechanism. The latter may in turn be influenced by afferent impulses 

 arising in other parts of the body, because it is a matter of common 

 experience that emotions or sensory impressions of different kinds 

 may inhibit or accelerate the activity of the intestinal musculature. 

 These impulses, in all probability, descend through the vagus system 

 and terminate in the mesenteric ganglion of the solar plexus, whence 

 they are relayed to the intra-intestinal mechanism by way of the mes- 

 enteric plexus. Regarding the latter, it has been proved by Burton- 

 Opitz^ that it contains efferent as well as afferent fibers for the 

 intestine. The fact that the vagus nerve constitutes the preganglionic 

 path of these musculomotor impulses seems definitely proved, because 

 its stimulation evokes strong contractions of the intestine. The claim 

 that the splanchnic nerve is the musculo-inhibitor nerve of the intes- 

 tine, need not be discussed at length, because it lacks a satisfactory 

 experimental basis. As has been stated above, the flaccidity of parts 

 ensuing in consequence of the stimulation of this nerve, may be due to 

 its vasoconstrictor action and the anemia resulting therefrom. To 

 summarize : (a) the intestine is in possession of a local nervous mech- 

 anism which renders it relatively independent of the central nervous 

 system, (6) systemic reflexes are made possible by the communications 



1 Jour, of Physiol., xxvi, 1901, 125. 



2 Zeitschr. fiir Biol., xxxii, 1899. 



3 Ergebn. der Physiol., 1908. 



4 Pfluger's Archiv, cxix, 1907, 451. 

 6 Ibid., cxxxv, 1910, 245. 



