Gelatin as prepared for the table contains a considerable proportion of water; as little as one per cent. of gelatin in water will cause it to gelatinise on cooling. Isinglass obtained from the floating bladder of the sturgeon is an example of the purest kind of gelatin; glue is an inferior sort, made from bones, etc. Gelatin is only a cheap food when obtained, for instance, from bones which cannot otherwise be utilised. When made from veal it is costly out of proportion to its dietetic value. The =Flesh= of various animals is one of the main sources of our nitrogenous and fatty food. Meats may be divided into two kinds, viz., =red meat= and =white meat=. These gradually merge into one another. As common examples of red meats, we have beef, mutton, pork, game, wild fowl, and salmon. The common fowl and turkey, most fishes, rabbits, crustaceans, and molluscs, are examples of white meat. As a rule white meats are more digestible than red, having more delicate fibres, and containing a smaller proportion of nitrogenous matter. Flesh consists almost entirely of muscular tissue, of which there are two kinds, striped and unstriped. The striped is the variety most commonly used as food. Unstriped muscle has a softer texture, but is not so easily masticated as striped, and for this reason may be indigestible. _Tripe_ is composed of the unstriped muscle and connective tissue of the stomach of the cow, and if well cooked forms a cheap and easily digested dish. _The influence of feeding_ on the quality of the meat is great. In ill-fed or old animals, connective tissue is more abundant, and the meat is tougher. Well-fed and fattened meat contains for equal weights much more nutritious matter than non-fattened meat, the fat which is deposited in the muscle replacing water and not proteid. Hence the gain in nutritive value is an absolute one, and is not attained at the expense of the proteid part of the meat. Young animals, again, contain more water and fat and a larger proportion of connective tissue than the full-grown, and are consequently not so nourishing. Meat ought to be eaten either before the onset of _rigor mortis_, or near its end, before putrefaction has commenced. During _rigor mortis_ it is denser, tougher, and more difficult to digest than after it. The proportion of fat in meat varies greatly in different individuals of the same species, in different animals, and in different parts of the same animal. According to Dr. Ed. Smith, the proportion of fat in fat oxen is ⅓, in fat sheep ½, in calves ⅙, lambs ⅓, and fat pigs ½.