[AS., saep.\ The fluid which flows through plants. The raw or crude sap consists of much water, with plant-food dissolved in it, entering through the roots. It rises through the outer part of the stem into the leaves, and is there converted into various non-nitrogenous sub-stances, composed chiefly of carbon, hydrogen, and oxygen, such as starch, gum, sugar, cellulose, and oil. In the sap there are also formed substances containing nitrogen, such as albumen and gluten. These substances are distributed to every part of the plant, helping to form and to fill new cells, and so aiding the life of the plant.