Muller has justly observed that these experiments of Magendie have thrown considerable light on the causes and the mode of treatment of the gout and calculous disorders. The subjects of these diseases are generally persons who live well and eat largely of animal food; most urinary calculi, gravelly deposits, the gouty concretions, and the perspiration of gouty persons, contain an abundance of uric acid, a substance in which nitrogen is contained in a large proportion. Thus, by diminishing the proportion of azotical substance in the food, the gout and gravelly deposits may be prevented. The experiments of Tiedemann and Gmelin have confirmed those of Magendie, whose curious observations on the necessity of varying diet I shall transcribe. 1. A dog fed on white bread, wheat, and water, did not live more than fifty days. 2. Another dog, who was kept on brown soldiers' bread did not suffer. 3. Rabbits and guineapigs who were fed solely on any one of the following substances--oats, barley, cabbage, and carrots,--died of inanition in fifteen days; but they did not suffer when these substances were given simultaneously or in succession. 4. An ass fed on dry rice, and afterwards on boiled rice, lived only fifteen days; a cock, on the contrary, was fed with boiled rice for several months with no ill consequence. 5. Dogs fed with cheese alone, or hard eggs, lived for a long time; but they became feeble and lost their hair. 6. Rodent animals will live a very long time on muscular substances. 7. After an animal has been fed for a long period on one kind of aliment, which, if continued, will not support life, allowing it the former customary food will not save it: he will eat eagerly, but will die as soon as if he had continued to be restricted to the article of food which was first given him. Dr. Paris is of opinion that all that these experiments tend to prove is, that animals cannot exist upon highly-concentrated aliment. Horses fed on concentrated aliment are liable to various disorders, originating from diseased action of the stomach and liver, broken wind, staggers, blindness, &c. Professor Muller has given an excellent definition of indigestion. "It is a state of the digestive organs in which either they do not secrete the fluid destined for the solution of the aliment, or they are in such a condition of irritability or atony, that by the mechanical irritation of the food, painful sensations and irregular motions are exerted."