PLATE XVIII.

CHAPTER X.

THE STOMACH, GALL-BLADDER, &c.

FIG. 1. a, the stomach; b, the cardia; c, the pylorus. The gastric juice is a secretion derived from the inner membrane of the stomach, and digestion is principally performed by it. In the various orders of animated beings it differs, being adapted to the food on which they are accustomed to subsist. The food, when properly masticated, is dissolved by the gastric fluid, and converted into chyme; so that most kinds of the ingesta lose their specific qualities; and the chemical changes to which they would otherwise be liable, as putridity and rancidity, &c. are thus prevented.

In this plate, h, the liver is turned up, in order to show the gallbladder which is attached to its concave surface; d, the duodenum; e, part of the small intestines; f, the pancreas; and g, the spleen.

FIG. 2. Explains the several ducts and their communication with the duodenum; a, the gall-bladder; b, the ductus cysticus; which uniting with, c, the ductus hepaticus, forms, d, the ductus communis ; which, after passing between the muscular and inner coats of the intestine, opens into it at e. f, the pancreatic duct. The bile is said to become more viscid, acrid, and bitter, from the thinner parts being absorbed during its retention in the gall-bladder.

PLATE XIX.

CHAPTER X.

THE LACTEALS, AND THORACIC DUCT.

The figure in this plate represents the course of the food, from its entrance at the mouth to its assimilation with the blood ; a, the œsophagus, extending from the pharynx to, b, the stomach; where the alimentary matter, having undergone the digestive process, is converted into chyme, a soft, homogeneous substance, and escapes at C, the pylorus, into, d, the intestines. In this plate a large portion of the latter is spread out to show a part of the absorbent system, called lacteals these collect and imbibe the chyle, or milky juice from the chyme, and transmit it through e, e, the mesenteric glands, into one general receptacle, f, (receptaculum chyli,) from which, g, the tho racic duct ascends in a more or less tortuous direction to the lower vertebræ of the neck, and after forming an arch, it descends and enters h, the left subclavian vein, at the point where that vein is united with the internal jugular. The absorbents of the right side frequently form a trunk, which enters the right subclavian vein.