A small division of the right lobe of the liver stands out between the main lobes. In this is located a long, narrow _gall-bladder_. Open the bladder by a longitudinal ventral incision. The opening into the _bile duct_ will be found near the anterior end of the bladder.
In Eugaleus, which does not possess such a median lobe, the gall-bladder lies hidden in the right lobe of the liver. It can be opened and explored, but the connection with the duct can usually be demonstrated only by scraping. Do this later.
The bile duct passes along the dorsal side of the gall-bladder and the edge of the gastro-hepatic and duodeno-hepatic omenta to the junction of the duodenum and large intestine, where it opens into the alimentary canal. Trace its oblique course through the wall of the intestine. The bile duct and the collecting (hepatic) ducts of the liver will be traced in the liver at a later stage of the dissection.
The _pancreas_ consists of two lobes; a slender lobe lying dorsal to and parallel with the stomach, and a flattened oval lobe lying upon the ventral surface of the duodenum, connected with the dorsal lobe by a slender bar of glandular tissue.
The _pancreatic duct_ passes from the extreme right end of the duodenal lobe obliquely through the wall of the intestine, opening into the anterior end of the large intestine. Free the edge of the lobe from the peritoneum and follow the duct.
Open the proximal limb of the stomach by a ventral incision which shall not cut any large blood vessels. Wash out the interior. Observe the three coats of the stomach; the outer peritoneal, the middle muscular, and the inner mucous coats. In the anterior portion of the stomach the mucous coat projects in the form of large papillae (absent in Eugaleus). Posterior to these, observe the irregular folding of the mucous coat, depending upon the degree of contraction of the muscular coat.
The muscular coat consists of an outer circular and an inner longitudinal layer of muscle fibres. Separate the two layers from each other and from the mucous coat; observe the network of blood vessels between the longitudinal muscles and the mucosa.
Open the pyloric end of the stomach, continuing the cut through the pylorus into the intestine. Examine the coats as before, observing especially that an outer layer of longitudinal muscle fibres is frequently developed, and that the pyloric valve is formed by an increase in the thickness of the coat of circular fibres.