CHAPTER II.

THE APPETITES OF HUNGER AND THIRST.

Hunger and Thirst, what they are--Generally referred to the stomach and throat, but perceived by the brain--Proofs and illustrations--Exciting causes of hunger--Common theories unsatisfactory--Hunger sympathetic of the state of the body as well as of the stomach--Uses of appetite--Relation between waste and appetite--Its practical importance--Consequences of overlooking it illustrated by analogy of the whole animal kingdom--Disease from acting in opposition to this relation--Effect of exercise on appetite explained--Diseased appetite--Thirst--Seat of Thirst--Circumstances in which it is most felt--Extraordinary effects of injection of water into the veins in cholera--Uses of thirst, and rules for gratifying it, 11–39