Why prepare a treatise on Heartwood and Tree Exudates? Why consider both topics together? What approach should be taken in their treatment? The exudates were one of the earliest items of trade between family, tribal, and racial groupings in prehistoric times. They became used extensively as items for the manufacture of implements and as commercial goods for illumination, for cosmetic, religious and magical purposes. Later heartwood from various trees entered intra­ and international trade for prestigious and religious buildings (when cedars were used), for the furniture (e.g., ebony, mahogany) of the nobility, for boats and vehicles. Consideration of their relevance to anthropology, and to the origin of technological developments in different primitive cultures, would satisfy a personal life-long interest. Attention to such a topic is urgently needed now that the development and destruction of land and forests is increasing and wiping out the traces of earlier people to meet the demands of the rapidly enlarging populations of today. The latter represents an even more urgent need. Increasingly, mankind will depend on renewable,resources produced at low energy cost. Forest products are one of these and the greater demands for them will require their growth and utilization with reduced loss and waste.

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1 Introduction.- 1.1 Prehistoric and Ancient Use.- 1.2 Changing Uses of Forests.- 2 Definitions and Descriptions.- 2.1 Introduction.- 2.2 Sapwood.- 2.2.1 Definitions.- 2.2.1.1 Sapwood.- 2.2.1.2 Included Sapwood.- 2.2.2 Area of Sapwood in Log Cross-Sections.- 2.2.3 Variation of Area of Sapwood.- 2.2.3.1 In a Species.- 2.2.3.2 In Different Species.- 2.2.3.3 Due to Age of Tree.- 2.2.3.4 Due to Rate of Growth.- 2.2.3.5 Due to Environment.- 2.2.4 Sapwood Contents.- 2.2.5 Discolored Sapwood.- 2.3 Intermediate Wood.- 2.3.1 Description.- 2.3.2 Occurrence.- 2.4 Transition Zone.- 2.4.1 Definition.- 2.4.2 Description.- 2.4.3 Occurrence.- 2.4.3.1 Heartwood Boundary Stain.- 2.5 Heartwood.- 2.5.1 Definition.- 2.5.2 Description.- 2.5.2.1 Appearance.- 2.5.2.2 Level of Maximum Area.- 2.5.2.3 Regular Heartwoods.- 2.5.2.4 Irregular Heartwoods.- 2.5.2.5 Variations in Appearance.- 2.6 Tree Exudates and Extracellular Materials.- 2.6.1 Definitions.- 2.6.1.1 Intercellular Secretory Spaces, Cavities, and Shakes.- 2.6.1.2 Intercellular Canals.- 2.6.1.3 Pitch Tubules and Stones.- 2.6.1.4 Pockets, Veins, and Streaks.- 2.6.2 Types of Exudate or Deposit.- 2.6.2.1 Resin.- 2.6.2.2 Gum.- 2.6.2.3 Kino.- 2.6.2.4 Latex.- 2.6.2.5 Manna.- 2.6.2.6 Amber.- 2.6.2.7 Balsam.- 2.6.2.8 Maple Sugar.- 2.6.2.9 Crystalline Compounds.- 2.6.3 Rate of Formation.- 3 Historical Aspects.- 3.1 The Use of Durable Woods.- 3.2 Exudates.- 3.3 Varnishes and Lacquers.- 3.4 Gums.- 3.5 Tannins.- 3.6 Dyes.- 3.7 Perfumes.- 3.8 Rubber.- 3.9 Medicines.- 3.10 Lessons from History.- 4 Influence of Forestry Aspects.- 4.1 Variation of Heartwood Volume.- 4.1.1 Heritability.- 4.1.2 Effect of Growth Rate and Crown Size.- 4.1.3 Influence of Environment.- 4.1.4 Influence of Injury and Health.- 4.2 Formation of Exudates.- 4.2.1 From Bark and Wood.- 4.2.2 From Wood.- 4.2.3 Addition of Stimulants.- 5 Chemical Features.- 5.1 Water and Gases.- 5.2 Inorganic Compounds.- 5.3 Storage Substances and Intermediates.- 5.4 Nitrogenous Compounds.- 5.5 Ethylene.- 5.6 Type of Extractives.- 5.6.1 Galactans and Cyclitols.- 5.6.2 Terpenoids.- 5.6.3 Fatty Acids and Related Compounds.- 5.6.4 Phenolic Compounds.- 5.6.4.1 Simple Phenols and Phenolic Acids.- 5.6.4.2 Lignans.- 5.6.4.3 Stilbenoids.- 5.6.4.4 Flavonoids.- 5.6.4.5 Quinones.- 5.6.4.6 Polymerized Polyphenols.- 5.6.4.7 In Different Tissues.- 5.7 Amount of Extractives.- 5.7.1 Position of Sample in the Tree.- 5.7.2 Effects of Rate of Growth 1ll.- 5.7.3 Effect of Site.- 5.7.4 Genetic Differences.- 5.7.5 Crystals.- 5.8 Reagents for Heartwood Detection.- 5.9 Exudates.- 5.9.1 Resin.- 5.9.2 Gum.- 5.9.3 Kino.- 5.9.4 Latex.- 5.9.5 Manna.- 6 Biological Features.- 6.1 Sapwood.- 6.1.1 Wood Tissues.- 6.1.2 Lumen Volume.- 6.1.3 Deposition of Extractives on Wall Surfaces.- 6.1.4 Impregnation of Cell Walls.- 6.1.5 Parenchyma.- 6.1.5.1 Volume.- 6.1.5.2 Cell Wall.- 6.1.5.3 Cytology.- 6.1.6 Respiration and Enzymes Activity.- 6.2 Transition Zone.- 6.2.1 Seasonal Variations.- 6.2.2 Appearance.- 6.2.3 Water Content.- 6.2.4 Pit Aspiration and Tylosis Formation.- 6.2.5 Cytology of Parenchyma Cells.- 6.2.6 Respiration.- 6.2.7 Enzyme Activity.- 6.2.8 Formation of Extractives.- 6.3 Heartwood.- 6.3.1 Seasonal Formation.- 6.3.2 Appearance.- 6.3.3 Respiration and Enzyme Activity.- 6.3.4 Location of Extractives.- 6.4 Wound Wood and Chemically Affected Wood.- 6.4.1 Wound Wood.- 6.4.2 Paraquat-Treated Woods.- 6.4.2.1 Biochemical Changes Due to Paraquat.- 6.4.3 Ethylene-Treated Wood.- 6.4.4 Knots.- 6.5 Exudates.- 6.5.1 General.- 6.5.2 Resin Formation.- 6.5.2.1 Anatomy of Pockets.- 6.5.3 Gum Formation.- 6.5.4 Kino Formation.- 6.5.4.1 Anatomy of Veins and Pockets.- 6.5.4.2 Chemistry of Kino Formation.- 6.5.5 Rubber Tapping.- 7 Function, Formation, and Control of Heartwood and Extractives.- 7.1 Function and Volume of Sapwood.- 7.1.1 Function.- 7.1.2 Volume.- 7.2 Types and Formation of Heartwood.- 7.2.1 Introduction.- 7.2.2 Types of Heartwood.- 7.2.2.1 Regular Heartwoods.- 7.2.2.2 Other Types.- 7.2.3 Conclusions.- 7.3 Features of Heartwood and Woundwood.- 7.3.1 Some Theories of Heartwood Formation.- 7.3.1.1 Natural Causes.- 7.3.1.2 Accumulation of Gas and Control of Water Content.- 7.3.1.3 Initiation by Fungi and Hormones.- 7.3.2 Anatomical Changes.- 7.3.3 Occurrence of Extractives.- 7.4 The Transition Zone and its Formation.- 7.5 Function of Extractives and Exudates.- 7.6 Formation of Exudates and Extractives.- 7.6.1 Differences in Composition.- 7.6.2 Site of Formation.- 7.6.2.1 Exudates.- 7.6.2.2 Extractives.- 7.6.3 Amounts.- 7.6.4 Type of Extractives in Tissues.- 7.7 Initiation of Formation of Heartwood, Extractives, and Exudates.- 7.7.1 Initiation by Displacement of Water.- 7.7.2 Initiation by Changes in Ethylene Levels and in Hormonal Balance.- 7.8 Factors Controlling the Nature of Extractives and Exudates.- 7.9 Activities at Cellular Levels.- 7.10 Conclusions.- References.