1. In the liver of portal cirrhosis there is a far freer communication between the arterial and portal currents than in the normal liver.
2. Factors contributing to the increased portal pressure in portal cirrhosis are (1) the direct communication of the arterial pressure to the portal vessels through dilated capillaries, (2) the larger volume-flow of the hepatic artery in proportion to the portal flow in cirrhosis as compared to that in the normal liver.
3. A portal cirrhotic liver gives passage to an amount of portal fluid proportionate to .its weight. There is no obstruction to the portal vessels from fibrosis in the large portal cirrhotic liver.
4. From an arterial inflow there is a free return flow through the portal as well as through the hepatic veins in both normal and cirrhotic livers.
5. From a portal inflow the return is through the hepatic vein only. The Gad's theory of valves and the arterial capillary network account for this fact.
6. The portal pressure has a decided influence on the arterial volume-flow and vice versa. This influence is more marked in the cirrhotic than in the normal liver.
7. The communication of the arterial pressure to the portal pressure is an important factor in an explanation of the increased portal pressure in portal cirrhosis.