TS 



In fact, the presence cf food is necessary to determine an action fcf the 

 parietes of the stomach, and as long as it is empty, there is nothing to 

 call forth such action. 



Those who think that hunger is mechanically produced by the weight 

 of the spleen and liver that keeps pulling down the diaphragm, which the 

 empty stomach no longer bears up, observe, that it may be appeased, for 

 a time, by supporting the abdominal viscera by means of a tight girdle ; 

 that hunger ceases as soon as the stomach is full, before the food can 

 have yielded to it any materials of nutrition. On this hypothesis, which 

 is purely mechanical, as that which explains hunger by the irritation of 

 the gastric juice, by the lassitude of the contracted muscles, by the com- 

 pression of the nerves, how shall we explain the fact, that when the hour 

 of a meal is over, hunger ceases for a time ? Ought not hunger, on the 

 contrary, to be considered as a nervous sensation which exists in the sto- 

 mach, is communicated by sympathy to all the other parts, and keeping 

 up an active and continuous excitement in the organ in which it is prin- 

 cipally seated, determines into it the fluids from all parts ? This pheno- 

 menon, like all those which depend on nervous influence, is governed by 

 the laws of habit, by the influence of sleep, and of the passions of the 

 mind, whose power is so great, that literary men, absorbed in meditation 

 and thought, have been known entirely to forget that they required food. 

 Every thing which awakens the sensibility of the stomach, in a direct or 

 sympathetic manner, increases the appetite, and occasions hunger. Thus, 

 bulimia depends, sometimes, on the irritation of a tape-worm in the or- 

 gans of digestion. The application of cold to the skin, by increasing, 

 from sympathy, the action of the stomach, has been known to "occasion 

 fames canina^ of which several instances are related by Plutarch (Life of 

 Brutus.) Ardent spirits and highly seasoned food, excite the appetite, 

 even when the stomach is overfilled. Whatever, on the contrary, 

 blunts or renders less acute the sensibility of the stomach, renders more 

 endurable or suspends the sensation of hunger. Thus, we are told by 

 travellers, that the Turkish dervises and the Indian faquirs, endure long 

 fasts, because they are in the habit of using opium, and lull, in a manner, 

 by this narcotic, the sensibility of the stomach. Tepid and relaxing 

 drinks impair the appetite; the use of opiates suspends suddenly the ac- 

 tion of the stomach. 



V. OfThirtt. The blood deprived of its serosity, by insensible per- 

 spiration and by internal exhalation, requires incessant dilution, by the 

 admixture of aqueous parts, to lessen its acrimony; and as the serosity 

 is incessantly exhausting itself, the necessity for repairing that loss is ever 

 urgent*. The calls of thirst are still more absolute than those of hunger, 



* As hunger seems to depend upon a certain condition of, or impression made upon, 

 these cerebral nerves distributed to the stomach, so thirst appears to arise from an alter- 

 ed state of the fluids, which state modifies the functions of the vessels, diminishes or 

 otherwise alters the condition of the fluids secreted in the mouth and fauces, and im- 

 presses the nerves of sensation, in these situations, in such a manner as to give rise to 

 tiie phenomenon under consideration. 



As the sense of thirst is induced by a state of the circulating fluids, which would be- 

 come hurtful to the system were it to continue for any .considerable period, so this sen- 

 sation is to be.regarded in the light of a watchful guardian, which both points out that 

 state, and the only way in which it can be removed. 



The super-abundance of saline or stimulating substances in the blood, is readily indi- 

 cated by the sensation induced in the mouth and fauces, which are the first, parts to 



