MOVEMENTS OF THE ALIMENTARY CANAL. 731 



and Doyon* has confirmed this result in cases in which the move- 

 ments and tonicity of the stomach were first increased by the action 

 of pilocarpin and strychnin. Cannon, in his observations upon cats, 

 found that all movements of the stomach ceased as soon as the 

 animal showed signs of anxiety, rage, or distress. 



Hunger Contractions. After the stomach has been empty for 

 a certain time we experience sensations of hunger that are more 

 or less of a subpainful character and are, therefore, frequently 

 designated as "hunger-pains." , These sensations appear and dis- 

 appear at irregular intervals until food is taken into the stomach. 

 Cannon and Washburn j first showed that these sensations appear 

 simultaneously with contractions of the stomach, and they sug- 

 gested that the hunger contractions cause the hunger-pains. 

 These particular movements have been investigated since by 

 Carlson J upon a man with a permanent gastric fistula. He finds 

 that the hunger contractions appear in groups, lasting for a certain 

 time, with intervening periods of quiescence. In each group the 

 beginning contractions are weak and slow, but there is an increase 

 in amplitude or vigor during the period, so that the climax is 

 reached at the end of the period. Chemical or mechanical stimu- 

 lation of the gastric mucosa or even the chewing of palatable food 

 inhibits the hunger contractions. The hunger contractions, like 

 the digestive contractions, continue when the extrinsic nerves are 

 severed. Presumably, therefore, both kinds of movement are 

 initiated and controlled through the intrinsic nervous apparatus. 

 The chief difference in character between the digestive and the 

 hunger contractions seems to lie in the fact that the former involve 

 mainly the antral end, while the latter are described as starting 

 from the region of the cardiac orifice and spreading as a peristaltic 

 wave over the whole stomach. It is stated that as the stomach 

 empties itself after a meal the peristaltic waves of contraction arise 

 nearer and nearer to the cardiac end and pass over gradually into 

 the hunger contractions characteristic of the empty stomach. 



Movements of the Intestines. The muscles of the small and 

 the large intestine are arranged in two layers, an outer longitudinal 

 and an inner circular coat, while between these coats and in the 

 submucous coat there are present the nerve-plexuses of Auerbach 

 and Meissner. The general arrangement of muscles and nerves is 

 similar, therefore, to that prevailing in the stomach, and in accor- 

 dance with this we find that the physiological activities exhibited 

 are of much the same character, only, perhaps, not quite so complex. 



* " Archiv de physiologie normale et pathologique," 1895, p. 374. 

 t Cannon and Washburn, "American Journal of Physiology," 29, 441, 1912. 

 j Carlson, "The Control of Hunger in Health and Disease," Chicago, 1916, 

 and numerous papers in "The American Journal of Physiology," vols. 31-42. 

 Rogers and Hardt, "American Journal of Physiology," 38, 274, 1915. 



