194 ANTHROPOLOGY. 



gus, and extending towards the duodenum. The second layer consists of 

 fibres running circularly in nearly parallel rings, beginning at the left 

 extremity. The third set of fibres take a very irregular or oblique direction, 

 and appear as a continuation of the circular fibres of the oesophagus. The 

 internal or mucous coat, also called villous, from its velvety appearance, is 

 continuous with that lining, the oesophagus, and duodenum. When fresh 

 and healthy, it is of a rosy or pinkish color. It is always thrown into folds or 

 wrinkles, some of w^hich are nearly parallel to the long axis of the stomach, 

 and thus permit the distension of this organ ; other folds intersect these, so 

 as to cause an areolated appearance. At the cardiac orifice this membrane 

 is folded longitudinally, and somewhat festooned. Corresponding to the 

 pylorus is a circular fold, with a small aperture in the centre, the pyloric 

 valve, encircled by a strong band of sphincter fibres ; during life, when the 

 sphincter acts, it can efiectually separate tlie stomach from the intestine. 

 When the stomach and duodenum are inflated and dried, the valve will be 

 seen to present an appearance not unlike that of the iris. On carefully 

 cleaning the inside of the stomach from all mucus, it will exhibit numerous 

 projecting papilhe, and between them small pits or depressions, studded with 

 minute holes. These pits are more or less circular, and most distinct 

 towards the pyloric orifice ; they secrete the gastric juice, the mucus being 

 probably furnished by the papillae. 



The stomach is freely supplied with blood from the coeliac axis ; the 

 coronary and epiploic arteries, with the vasa brevia, inclose it in a network 

 of inosculation. The numerous large veins enter into the portal system. 

 The eighth nerves expand on its surface, and form a plexus round the car- 

 diac orifice. Numerous nerves also are derived from the solar plexus of the 

 sympathetic. 



The mucous coat of the stomach secretes the peculiar anti-putrescent and 

 powerfully solvent liquid known as the gastric juice. By its action, aided 

 by the temperature of the body and the motion of the stomach, food intro- 

 duced through the oesophagus is, after a time, converted into a grey pulpy 

 mass termed chyme. It is probable that the saliva (mixed with which the 

 food comes to the stomach) performs an important part in the operation of 

 digestion. 



2. The Duodenum is the next portion of the alimentary canal. It is so 

 named from its length (from eight to nine inches), being about equal to the 

 breadth of twelve fingers. This is the first and shortest, but most dilatable 

 division of the small intestine ; it extends from the pylorus to the root of the 

 mesentery, where the jejunum commences. The su2)erior transverse portion 

 ascends from the pylorus backwards and to the right, where it makes a sud- 

 den or acute turn, and the middle or perpendicular p'ortion then descends in 

 front of the right kidney as low as the third lumbar vertebra ; here it makes 

 a second turn, from which the inferior transverse portion extends obliquely 

 across the spine. The biliary and pancreatic ducts perforate the inner side 

 of the perpendicular division of the duodenum. These' pass through its 

 coats very oblic^uely, and open into the intestine, sometimes separately, 

 sometimes together, on a small papilla opposite the inferior angle. In the 

 900 



