PHYSIOLOGY. 



" As this common account, therefore, is not satisfactory, I be- 

 lieve that hunger is produced merely by the state of contraction 

 of the muscular fibre, to which the emptiness of the stomach 

 gives rise. This contraction gives a sensation of consciousness, 

 which in cases of spasmodic contractions is very painful, and, 

 though it does not amount to the same degree here, still may 

 be a cause of uneasiness, and sometimes of pain. Hence, in 

 order to account for the sensation of hunger, it is only necessary 

 to shew by what means this contraction is actually produced, 

 and how it comes to be connected with a state of emptiness in 

 the system. 



" But I must first observe, that another account of this sensa- 

 tion has been given by imputing it to the operation of certain 

 acrid matters upon the sensible coat of the stomach. I allow 

 that acrid matters may occur in the stomach, especially in its 

 most empty state, when they will also be applied in the greatest 

 proportion to the surface of the stomach, which, towards the end 

 of digestion, is diminished in extent. I also believe that these 

 acrid matters have a share in exciting the appetite, because this 

 effect can be produced by introducing analogous acrid matters, 

 such as acids, into the stomach. But it is very improbable, that 

 a state of acidity, or any other acrimony should be present in 

 the stomach, regular in quantity and proportion, considering 

 the varieties of aliment and of digestion ; but hunger is very re- 

 gular in its action, which leads me to believe that its return is 

 not caused by those acrimonies. Supposing, however, that they 

 have a share in producing hunger, it is still a question whether 

 they act by giving a degree of pain, or whether they do not, in 

 the first place, excite the state of contraction on which I say that 

 appetite essentially depends. 



" This view, therefore, will not disturb the general theory which 

 I wish to establish, that hunger depends on a contraction of the 

 muscular fibres of the stomach. I have to remark, that the 

 above accounts are especially defective in not pointing out the 

 state of appetite as connected with the general state of the sys- 

 tem, and with the evacuations that daily occur and occasion 

 the waste which requires to be daily supplied. 



" It is certain that where the appetite is remarkably deficient, 

 the evacuations also are diminished ; and this is so suitable to 



