digestion is vigorously carried on. Fourthly, the food must be in a form in which it does not irritate the stomach, provoking an outflow of acid out of proportion to the pepsin which accompanies it. Experience alone can teach the foods which are to be avoided on this account. But speaking generally, it may be said that the stomach resents the presence of substances which cannot be amalgamated into chyme. Its task is the reduction of the mixture of foods which compose a meal to the consistence of a smooth cream. Hot buttered toast or pie-crust are made of wholesome constituents enough, but, fat being melted into the starch, the fragments are impermeable to the gastric juice. They act mechanically as irritants of the mucous membrane. Again, it may be said that “pure” foods are apt to provoke acidity. Nothing could be more wholesome than eggs or pounded meat or custard pudding; but taken by themselves these articles of diet over-stimulate the mucous membrane. They need to be diluted with starch-foods, or even with cellulose. And this calls attention to the dietetic value of vegetables. Vegetables, which consist chiefly of innutritious cellulose, distribute the digestible constituents of a meal and increase its bulk, greatly favouring its progress through the alimentary canal. Especially in herbivora is it important that the bulk and looseness of the food should be well maintained. Rabbits thrive on sugar, starch, and albumin, mixed with such an absolutely indigestible substance as horn-shavings. If the inert substance be omitted, they die of intestinal inflammation, although fed on the same mixture of pure foods. Other rules which govern digestion might be mentioned; and it is needless to point out that, when the mechanism is deranged, steps adapted to the particular malady must be taken to bring it back to a normal condition. There is, however, one precaution upon which, in a certain number of cases, it is impossible to lay too much stress. The digestion of proteins is seldom carried out satisfactorily when much sugar, and especially much cane-sugar, has been eaten at the same meal. Excessive lactic fermentation prevents the proper peptonization of meat. The chemistry of digestion is not sufficiently well understood to enable the physiologist to say what is amiss; but probably by-products of peptic digestion are produced. To many people this is of little consequence; but to those who exhibit a gouty tendency it is, unfortunately, a most serious matter. Civilized races are particularly subject to the uric acid diathesis. In the course of nitrogenous metabolism uric acid is formed in place of fully oxidized and easily soluble neutral urea. Although the chemical sequence has not been discovered as yet, there is no question but that imperfect gastric digestion means the formation of uric acid, with all its lugubrious results: malaise, neck-ache, emotional depression. Birds and reptiles