502 TEE DIGESTIVE APPARATUS IN MAMMALIA. 



lobular venous plexuses " into those branches of the portal vein situated in th€ 

 interlohuJar fissures, but not to those in the sjmces, which, being larger, and giving 

 origin to those in the fissures, are the last to be congested." In this second stage 

 the liver has a mottled appearance, the non-congested substance is arranged in 

 isolated, circular, and ramose patches, in the centres of which the spaces and 

 parts of the fissure are seen. This is an extended degree of hepatic venous 

 congestion ; it is " active congestion " of the liver, and very commonly attends 

 disease of the heart and lungs. 



These are instances of partial congestion ; but there is sometimes general 

 congestiot of the organ. " In general congestion, the whole liver is of a red 

 colour, but the central portions of the lobules are usually of a deeper hue than 

 the marginal portions.") 



Development. — The liver of the foetus is remarkable for its enormous 

 development. Its function commences early, for at birth the intestines are filled 

 with meconium — a product of the biliary secretion. A more detailed description 

 will be given when the general development of the foetus comes to be studied. 



2. The Pancreas. 



This organ has the greatest resemblance to the salivary glands in its structure 

 and physical properties ; and for this reason it has been named the abdominal- 

 salivary gland.. 



Situation — Weight. —It is situated in the sublumbar region, across the aorta 

 and posterior vena cave, in front of the kidneys, and behind the liver and 

 stomach. Its weight is seventeen ounces. 



Form and Relations. — The pancreas is rather irregular and variable in form, 

 according to the kind of animal. Flattened above and below, traversed obliquely 

 from its inferior to its superior face by an opening for the passage of the portal 

 vein, and which is named the pancreatic ring, this gland is sometimes triangular, 

 sometimes oblong, and curved on itself ; it is under the latter form that we will 

 notice it. 



Its fifces present the lobulated aspect of salivary glands. The superior 

 adheres by connective tissue to the aorta, posterior vena cava, coeliac trunk, solar 

 plexus, splenic vessels, and the right kidney and supra-renal capsule ; it is 

 covered by the peritoneum for a certain portion of its extent. The inferior is 

 related to the base of the caecum and the fourth portion of the colon, through 

 the medium of a thick layer of connective tissue. The anterior border, concave 

 and undulating, is in contact with the duodenum and the left extremity of the 

 stomach. The posterior is very convex, especially to the right, and near its 

 middle it presents a notch for the reception of the portal vein before its entrance 

 into the ring. The right extremity (or head) — the thinnest — adheres to the 

 duodenum, and shows the excretory ducts of the gland. The left is carried 

 towards the base of the spleen, in passing between the left extremity of the 

 stomach and the kidney of the same side. 



Structure. — Superficially, it resembles the salivary glands, but in reality it is not 

 a racemose gland. It is an acinous gland in which the elongated culs-de-sac, filled 

 with polyhedral cells, have their axis occupied by a vessel and a cord of connective 

 tissue. The excretory vessels disappear on reaching these culs-de-sac, so that the 

 secreted products are infiltrated between the cells to reach the duct of Wirsung. 



The gland receives its blood by the hepatic and great mesenteric arteries ; 

 the nerves come from the solar plexus. 



