OF HUNGER AND THIRST. STARVATION. 391 



2. Of Hunger and Thirst; Starvation. 



412. The want of solid aliment, arising out of the several sources of demand 

 formerly enumerated ( 374-6), is indicated by the sensation of Hunger; and 

 that of liquid by Thirst. The former of these sensations is referred to the sto- 

 mach, and the latter to the fauces; but although certain conditions of these 

 parts may be the immediate cause of the sensations in question, they are really 

 indicative of the requirements of the system at large. For the intensity of the 

 feelings bears no constant relation to the amount of solid or liquid aliment in 

 the stomach ; whilst, on the other hand, it does correspond with the excess of 

 demand in the system, over the supply afforded by the blood ; and it is caused 

 to abate by the introduction of the requisite materials into the circulating fluid, 

 even though this be not accomplished in the usual manner by the ingestion of 

 food or drink into the stomach. 



413. That the sense of Hunger, however, is immediately dependent upon 

 some condition of the Stomach, seems to follow from the fact that it may be 

 temporarily alleviated by introducing into the digestive cavity matter which is 

 not alimentary. Of the precise nature of that condition, however, we have no 

 certain knowledge. It is easy to prove that many of the causes which have 

 been assigned for the sensation, are but little, if at all, concerned in producing 

 it. Thus, mere emptiness of the Stomach cannot occasion it; since, if the pre- 

 vious meal have been ample, the food passes from its cavity some time before 

 the uneasy feeling is renewed ; and this emptiness may continue (in certain dis- 

 ordered states of the system) for many hours or even days, without a return of 

 desire for food. Besides, the stomach may be filled with food, and yet Hunger 

 may be intensely felt, if, from disease of the pylorus or any other cause, there 

 be an obstacle to the passage of the aliment into the intestine, and to the com- 

 pletion of the processes of chylification and absorption, so that the system needs 

 that which the digestive apparatus is unable to provide for it. Again, the sense 

 of Hunger cannot be due, a& some have supposed, to the action of the gastric 

 fluid upon the coats of the stomach themselves; since this fluid is not poured 

 into the stomach, except when the production of it is stimulated by the irrita- 

 tion of its secreting follicles. It is thought by Dr. Beaumont that the disten- 

 sion of these follicles with the secreted fluid is the proximate cause of hunger; 

 but there is no more reason to believe, that the secretion of gastric fluid is accu- 

 mulating during the intervals when it is not required, than there is in regard to 

 saliva, the lachrymal fluid, or any other secretions, which are occasionally poured 

 out in large quantities under the influence of a particular stimulus; and, more- 

 over, it is difficult to imagine how mental emotion, or any impression on the 

 nervous system alone (which is able, as is well known, to dissipate the keenest 

 appetite in 'a moment), can relieve such distension. It may, perhaps, be a more 

 probable supposition, that there is a certain condition of the Capillary circula- 

 tion in the Stomach, which is preparatory to the secretion, and which is excited 

 by the influence of the Sympathetic nerves, that communicate (as it were) the 

 wants of the general system. This condition may be easily imagined to be the 

 proximate cause of the sensation of hunger, by acting on the nervous centres. 1 



1 It was maintained by Brachet, that the senses of Hunger and Satiety are annihilated 

 by section of the Pneumogastric nerves ; which, if true, would strongly confirm the view 

 that the immediate source of these senses lies in the condition of the Stomach. But the 

 researches of other experimenters, particularly those of Dr. John Reid (" Edinb. Med. and 

 Surg. Journ.," April, 1839, and "Physiological, Anatomical, and Pathological Researches," 

 pp. 234-239), do not confirm this view ; for they seem to show that after the immediate 

 eifect of the operation has subsided, animals take food with no less avidity than previously. 

 It appears, however, from Dr. Reid's observations, 'as well as from those of Valentin, that 



