When small dosages of adrenalin are perfused by way of the portal vein through the excised, surviving liver of the rabbit, cat and vervet monkey, the outflow of liquid through the inferior vena cava becomes markedly accelerated and the vol. of the organ diminishes. Atropine produces a similar result. Large doses of adrenalin reduce hepatic outflow and diminish liver vol. Pilocarpin, eserine and acetyl-[beta]-methyl-choline chloride ("Mecholyl"-Merck) produce swelling of the liver and reduction of the outflow of liquid through the inferior vena cava. The effects of pilocarpin, eserine, acetyl-[beta]-methylcholine chloride and small doses of adrenalin can be explained in terms of the action of a complex valve (sluice valve) consisting of the walls of the sublobular veins and the small and large endothelial tubes (sluice channels) which enter these veins more or less perpendicularly. Pilocarpin, eserine and acetyl-[beta]-methylcholine chloride (in proper dosage) cause the musculature in the walls of the sublobular veins to contract and thereby close (partially or totally) those portions of the endothelial tubes which are situated in the walls of these veins. The lumina of the large endothelial tubes (the central veins) also become greatly narrowed as the result of the contraction of the musculature in the walls of the sublobular veins. The "sluice valve" may be opened up widely by atropine or small doses of adrenalin.