OEGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 427 



proportion of blood contained within these two sets of vessels ; and so long 

 as the circulation is natural, the colour will be uniform. But the instant 

 that any cause is developed which shall interfere with the free circula- 

 tion of either, there will be an immediate diversity in the colour of the 

 lobule. 



Thus, if there be any impediment to the free circulation of the venous 

 blood through the heart or lungs, the circulation in the hepatic veins will 

 be retarded, and the sublobular (or supralobular) and intralobular veins 

 will become congested, giving rise to a more or less extensive redness in the 

 centre of each of the lobules; while the marginal or non-congested portion 

 presents a distinct border of a yellowish white, yellow, or green colour, 

 according to the quantity or quality of the bile it may contain. " This is 

 'passive congestion' of the liver, the usual and natural state of the organ 

 after death ;" and, as it commences with the hepatic vein, it may be called 

 the first stage of hepatic venous congestion. 



But if the causes which produced this state of congestion continue, or be 

 from the beginning of a more active kind, the congestion will extend through 

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

 in the interlobular fissures, but not to those in the spaces, 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 

 congestion 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. It is situated in the sublumbar region, across the aorta and 

 posterior vena cava, 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 from above to 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 faces present the lobulated aspect of salivary glands. The superior 

 adheres by cellular 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 responds to the base of the caecum and the fourth portion of the 



