The author gathered leaves from pine trees and from broad-leaved evergreen shrubs monthly through 3 years, crushed out the sap and tested it for freezing point depression. In summer when sap flows freely it is relatively thin and could be frozen easily. As autumn comes the starch in the leaves is converted into sugars and oil, changing the sap into a sirupy emulsion difficult to freeze. Greatest density of the sap occurred in late January and February. Deciduous trees show some sap thickening in late autumn, but apparently the sugars are transferred into the tree before the leaves drop, as sap pressed from leaves just fallen was easily frozen, whereas sap from leaves not quite ready to fall resisted the effects of considerably lower temperatures.