Mall1, 2 appears to have been the first to record the portal venous pressure in animals under experimental conditions. The later determinations by Burton-Opitz3, 4, 5 were shortly followed by Tiger-stedt's6 records. These observers used the technically difficult T-cannulation of the portal vein, although this itself probably interfered with the normal pressure under investigation. In the experimental animal, we7 have employed cannulation of the divided inferior mesenteric vein, cannulation of a divided splenic vein (as suggested by Bayliss and Starling), and T-cannulation of the portal vein itself. The height of a column of physiologic saline solution above the portal vein sustained in a vertical tube attached to the cannula was taken as the portal pressure. In our animal, the portal pressure was always about 10 cm saline higher than the venous pressure simultaneously determined in the lower extremity. This communication is intended to record a series of portal venous pressures determined at laparotomy in...