Owing to this extreme simplicity of organization, a hydra may be cut into pieces, each of which will become a perfect animal. But in proportion as we ascend in the scale of creation, the organization becomes more complicated, and the functions more numerous and also more dependent on each other; so that, when we arrive at man--the highest of all--we find that the loss or injury of any vital organ puts a stop to, or impairs, the action of all the rest. It is impossible, however, in an elementary work like this, to trace the gradation through the different series of animals. We must confine our examination to man, and only borrow from other creatures such illustrations as may be necessary for throwing light upon the human structure. In man, then, the stomach is a large membranous and muscular bag, lying under the convexity of the lower ribs of the left side, and stretching towards the right a little beyond the hollow commonly called the pit of the stomach. In shape it somewhat resembles the bag of a bagpipe, as will be seen from the figure on page 67; its left or larger extremity being in contact with the ribs, and its right or narrow extremity situated under the pit of the stomach. The position of the stomach (St^m.) relatively to the chest, bowels, and liver, will be understood by inspecting the figure on the next page. It is separated from the cavity of the chest by the diaphragm or midriff DD, with which its upper surface is in immediate contact, and through which the gullet passes to enter its left extremity. Its right or _pyloric_ extremity, marked P in the cut on the opposite page, lies close to the lower surface of the liver (Liv^r.), the latter being a little displaced to shew its situation. On the lower surface it has the appearance of resting on the intestines, as if imbedded among their folds. [Illustration] The parts of the stomach which have received names and require to be noticed, are,--the _cardiac_ orifice (marked C in the next figure, and so named from being near the κεαρ, _kear_, or heart), in which the gullet terminates, and through which food and drink are introduced; P, the _pylorus_, or pyloric orifice (from πυλωρος, _pyloros_, a _gate-keeper_, because it allows none but digested food to pass out), where the intestine called the _duodenum_ begins, and through which the chyme passes after digestion is completed, and which, when the stomach is full, is nearly on a level with the cardia, although when empty it is lower; SS, the _smaller arch or curvature_; and GGG, the _greater arch or curvature_. The spleen is attached to that part of the larger arch marked with dotted points. From the situation of the cardia C, and its connection with the gullet, it will be at once perceived that this forms one of the points of attachment by which the stomach is retained in its place. [Illustration]