Maximum water intake occurs both with anoxia and with exposure to oxygen when animals have received no food during 20 to 24 hours. It diminishes almost immediately after the ingestion of food and is least after 8 to 10 hours when digestion is nearly complete. These changes coincide with the passage of amino acids from the gastrointestinal tract to the liver by way of the blood.

Movement of water into the liver cells is favorable to the entrance of dissolved substances and when it is greatest with approaching anoxia the movement promotes the diffusion of oxygen into the cells.