CUTANEOUS AND INTERNAL SENSATIONS. 291 



was filled with food. It is possible, of course, that in such cases 

 the sensations of hunger are not produced by general changes in the 

 tissues, but are due to some chemical change in the blood that 

 affects the hunger apparatus of the stomach. What we usually 

 mean by hunger is a sensation that is referable to changes in the 

 stomach and disappears normally when the stomach is supplied 

 with food. Cannon and Washburn* have shown that when the 

 stomach is empty the hunger sensations may appear and disappear 

 at certain intervals, and they have demonstrated experimentally 

 that the appearance of a hunger pain is simultaneous with a con- 

 traction of the musculature of the stomach. They propose the 

 theory that hunger sensations or hunger pains are caused by con- 

 tractions of the stomach, the contractions affecting presumably 

 some as yet undescribed sensory apparatus. Carlson f has reported 

 observations upon a man with a permanent gastric fistula, which 

 corroborate the results of Cannon and Washburn. As soon as 

 the stomach is empty these hunger contractions make their appear- 

 ance, but mechanical or chemical stimulation of the mucous 

 membrane of the mouth, esophagus, or stomach causes them to 

 disappear through a reflex inhibition. The efferent fibers con- 

 cerned in this inhibition run in the splanchnic nerves. Since the 

 hunger contractions occur after section of both vagi and splanch- 

 nics, it is evident that the essential mechanism concerned is 

 wholly intrinsic, involving, probably, the local nerve plexuses 

 in the walls of the stomach. The vagi exert a tonic influence on 

 the apparatus, while, as just stated, its activity is readily in- 

 hibited through the splanchnic paths. Since the hunger pains 

 and the hunger contractions disappear when food is eaten, and 

 while the stomach is in active digestion, it seems evident that the 

 ordinary movements of the stomach during digestion are of a 

 different order from those contractions that cause hunger pains. 

 It is suggested that the latter involve mainly the fundus or body 

 of the stomach. Some confusion has existed in regard to the sig- 

 nificance of the terms "hunger" and "appetite." Most writers have 

 been inclined to use these terms to indicate different degrees of 

 activity of the same sensory apparatus, appetite being employed 

 to describe the milder forms of hunger as contrasted with the 

 stronger and more disagreeable sensations designated as hunger 

 pains or hunger pangs. Other authors consider that hunger 

 and appetite constitute two different sensations mediated pre- 

 sumably by two different physiological mechanisms. Thus, 

 Cannon and Washburn define appetite as a kind of pleasurable 



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

 t Carlson, ibid., 31, 151, 1912, and 31, 175, and 212, 1913; also vols. 32, 33, 

 34, and 36. 



