PHYSIOLOGY. 



Digestion. Is a function common to all 

 animals, by which foreign substances, in- 

 troduced into their bodies, and submitted 

 to the action of certain organs, change 

 their qualities and form a new compound, 

 fit for the purposes of nourishment and 

 growth. Animals alone are provided with 

 digestive organs ; all, from man to the 

 polype, have an alimentary cavity, and 

 its existence is, therefore, an essential 

 character of animals. The loss which the 

 body sustains in performing the various 

 actions that take place in the living ani- 

 mal machine, is supplied by means of the 

 food. Hunger and thirst admonish us of 

 the wants of our frame, and the pleasures 

 of the palate are a no less strong induce- 

 ment to the procuring and taking of 

 food. 



The cause of hunger has been placed 

 in the mutual attrition of the rugae of the 

 empty stomach ; in the irritation produc- 

 ed by the gastric juice, Sec. Perhaps it 

 may be derived more justly from a sym- 

 pathy between the stomach and the body 

 at large. For when, in diseases of the 

 pylorus, the food cannot be transmitted 

 into the intestines, and does not there- 

 fore enter the system, great hunger is 

 experienced, even although the stomach 

 may be filled. Much depends on habit, 

 and on the operations of mental cau- 

 ses : hunger is felt at the usual periods 

 of our repasts ; and, if it be not then re- 

 moved by eating, will often cease spon- 

 taneously. The man of letters, absorbed 

 in meditation, often forgets the natural 

 wants of his body. Whatever diminishes 

 the sensibility of the stomach makes hun- 

 ger more tolerable. Thus, the Indian 

 and Turkish fanatics (Mollahs and Fa- 

 kirs) are said to support their long fasts 

 by the habitual use of opium. Thirst 

 seems to consist more in a very trouble- 

 some dryness of the fauces and oesopha- 

 gus, and in a peculiar irritation of these 

 parts from the admixture of acrid, and 

 particularly saline matters, with the food. 

 The necessity of obeying both these calls 

 varies according to the age, constitution, 

 and particularly the habits of individuals : 

 yet we may state, on the whole, that a 

 healthy adult could not abstain from food 

 for a whole day without bringing on con- 

 siderable weakness ; and that this absti- 

 nence could not be continued to the 

 eighth day without the most imminent 

 risk of life. Continued abstinence dimi- 

 nishes the weight of the body to a de- 

 gree which becomes sensible in twenty- 

 four hours, causes absorption of fat, great 

 prostration of strength, increased sensi- 



bility with watchfulness, and a most pain- 

 ful dragging at the epigastric region. 

 Hunger is more speedily fatal in proper- 

 tion to the youth and strength of 1 the 

 individual. Thus, the wretched father, 

 whose dreadful history is immortalised by 

 Dante, shut with his children in a dun- 

 geon, perished last, on the eighth day of 

 confinement, after witnessing the death 

 of his four sons, amid the convulsions of 

 rage and cries of despair. We meet 

 with a large collection of examples of 

 long abstinence in the great work of 

 Haller ; but they do not seem to possess, 

 in every instance, the requisite authenti- 

 city. Many of the subjects were weak 

 and delicate women, living in a state of 

 almost complete inaction, where the 

 powers of life, almost extinct, were only 

 evinced by a very low pulse and respira- 

 tion repeated at long intervals. They 

 might be compared to hybernating ani- 

 mals, where the waste, occasioned by the 

 functions of active life, does not take 

 place, and where consequently the usual 

 supplies cannot be needed. Although the 

 admonitions of thirst are very imperious, 

 yet drink does not seem so necessary to 

 life and health as solid food. The mouse, 

 quail, parrot, and several other warm- 

 blooded animals never drink, and in- 

 stances have been known in the human 

 subject. Thirst always becomes greater 

 when any watery secretions are much 

 augmented, as in dropsy, and particularly 

 in diabetes. 



In the dispute, whether man be natu- 

 rally carnivorous or herbivorous, we are 

 inclined to suppose that truth lies on 

 neither side. That the structure both of 

 the teeth and intestines, as well as of the 

 joint of the lower jaw, occupies a middle 

 place between the two just mentioned, 

 and constitutes him an omnivorous ani- 

 mal. This, indeed, seems to follow ne- 

 cessarily from the unlimited extent of his 

 habitation ; he can dwell in every coun- 

 try and climate of the globe ; and makes 

 use, in various situations, of every variety 

 of alimentary matter, furnished by the 

 animal and vegetable kingdoms. 



The food of man, and probably of every 

 animaj, is derived from organized matter. 

 Nothing seems capable of furnishing 

 nourishment that has not lived : the mi- 

 neral kingdom, indeed, supplies some ar- 

 ticles of seasoning, which are mixed with 

 our food, and various medicines and 

 poisons, which do not seem to be nu- 

 tritious. 



As .man on the one hand is a most truly 

 omnivorous animal, and capable of con- 



