1. By using adrenaline during the perfusion of the portal system of the liver it has been shown that the radicles of this vein possess motor activity.

2. Stimulation of the distal end of the hepatic plexus during the perfusion, as well as in an animal possessing a normal portal circulation, has proved that this motor mechanism is innervated by the aforesaid plexus.

3. It has also been established that the portal mechanism is distinct from the one located in the terminals of the hepatic artery, and that it embraces not only the distributing tubules, but also extensive areas of the central or collecting channels.