The term wood extractives covers a large number of different compounds which can be extracted from wood by means of polar and non-polar solvents. In a narrow sense extractives are those compounds which are soluble in organic solvents, and in this sense the term extractives is used in wood analysis (-» 3.2.4.). But watersoluble carbohydrates and inorganic compounds also belong to the extractable substances.The portion soluble in organic solvents amounts to only few percent in the wood of trees from temperate zones, but the concentration can be much higher in certain parts of a tree, e.g. in branch bases, heartwood, roots, areas of sore irritation. Relatively high amounts of extractives are found in certain tropical and subtropical woods (Table 3-6). Various studies are concerned with the artificial induction of a high extractive production (up to 15%) in pines. In the case of treatment with the herbicide paraquat or similar compounds before harvest, areas soaked with resin (lightwood) are formed within the stem (Conner et al. 1977; Zinkel, McKibben 1978) (-» 18.7.).