I05 6 THE SENSES 



the night. After the first day of starvation the hunger sensation 

 referred to the epigastrium was almost continuous, and did not 

 wholly disappear during the intervals between the periods of 

 vigorous gastric contractions. This feeble continuous hunger sen- 

 sation was obviously associated with the increased tonus and the 

 more or less continuous, although weak, rhythmical contractions 

 that correspond to the periods of relative quiescence of the empty 

 stomach during prolonged starvation. The precise manner in which 

 the hunger contractions of the stomach arouse the pangs or pains 

 of hunger remains in doubt. Since the sensation has a specific 

 character, it is to be supposed that it is subserved by a special 

 sensory apparatus with receptors in the stomach. The vagi dp not 

 seem to be concerned. But the gastric contractions during digestion of 

 a meal notoriously do not cause such sensations, and therefore it has 

 been suggested that the nervous mechanism associated with the 

 local sensation of hunger becomes more and more excitable in the 

 absence of food, until at last the threshold is reached at which the 

 stimulus connected with the hunger contractions becomes effective. 

 It comes to the same thing to say that the presence of food in some 

 way inhibits the discharge which leads to the sensation. This, 

 however, is only another way of saying that the true explanation is 

 still to seek. 



Carlson was unable to confirm the common statement that 

 hunger disappears after the third day of starvation, although there 

 was certainly some decrease in the sensation of hunger, and especi- 

 ally in appetite, on the fourth and fifth days. As has been often 

 shown, the deprivation of food for long periods, or even till death, 

 when water is allowed, is not associated with acute suffering. 



Appetite -is distinguished from hunger by those observers who 

 have studied the question most precisely, but of the physiological 

 basis of the sensations that constitute appetite we know even less 

 than we do of the physiological basis of hunger. The taking of 

 food blunts the appetite, as it stills hunger. Fasting evokes both. 

 Yet during a prolonged fast, appetite, the desire for food and the 

 pleasure in the thought or at the sight of it, may disappear, or be 

 much lessened, while the hunger pangs are still sharp. The smell 

 and taste of agreeable food and the mental representations of these 

 sensations are elements in appetite, and even the associations con- 

 nected with the time and place of a customary meal and with those 

 who share it. But there is a gastric element as well: the mere 

 filling of the stomach apart from the passage of nutrient material 

 into the blood helps to satisfy the appetite; the emptying of the 

 stomach in the course of digestion seems of itself to take a part in 

 restoring the appetite for the next meal. To what extent, if at all, 

 the gastric element in the sensation of appetite is dependent upon 

 the same mechanism as the gastric element in hunger is unknown. 



