_The Stomach._ The stomach was sectioned in three regions, as shown in Figure 35: (1) in the cardiac region very near the opening of the œsophagus; (2) in the middle or fundic region; and (3) in the region near the opening of the pylorus. The first two sections are in the first or large region of the stomach; the third section is in the second or small region of the stomach (Fig. 35). The wall as a whole is thickest in the fundus, being there practically twice as thick as in the pyloric and half again as thick as in the cardiac region. This great thickening is due mainly to a thickening of the middle or oblique layer of muscle, which is here remarkably developed. The mucosa is of nearly uniform thickness in the different regions and will be described later. Since there is no striking difference beside that of thickness in the general structure of the wall of the different regions, the pyloric region, as seen under low magnification, will now be described (Fig. 45). The mucosa, _m_, consists of fairly long glands underlaid by a well-marked muscularis mucosa, _mm_, the latter exhibiting a compact circular layer over a wider but more scattered layer of longitudinal fibers. A considerable amount of fibrous connective tissue lies among the muscle fibers. The circular layer of the muscularis mucosa sends towards the surface numerous strands or septa between the glands; six or eight of these are seen in the figure. These strands are not nearly so numerous in the large region of the stomach. As was said, the outer or longitudinal layer of the muscularis mucosa is wider but less compact than the circular and its bundles of fibers are seen in the figure as a layer of large, scattered dots just beneath the circular layer. The submucosa, _sm_, is of average thickness and density. In the fundic and cardiac regions it seems to extend between the circular and oblique layers; at any rate, there is a considerable layer of connective tissue between these two muscular layers. The circular muscular layer, _cm_, is of only moderate thickness and is of rather a loose character. In the pyloric region it is not very distinct from the underlying oblique layer, but in the other regions, as has just been said, it is separated from the oblique layer by a considerable layer of connective tissue like that of the submucosa. The oblique layer, _om_, even in this section of the pyloric region is the thickest of the three muscle layers; while in the cardiac, and especially in the fundic, regions it is of great thickness, as was noted above, and is made up of larger bundles with less intervening connective tissue. [Illustration: FIG. 45. A transsection through the wall of the pyloric region of the stomach of the feeding animal, under low magnification; _m_, mucosa; _om_, oblique muscles; other letters as in Figure 42.]