John W. Rowe

Wood as found in trees and bushes was of primary importance to ancient humans in their struggle to control their environment. Subsequent evolution through the Bronze and Iron Ages up to our present technologically advanced society has hardly diminished the importance of wood. Today, its role as a source of paper products, furniture, building materials, and fuel is still of major significance. Wood consists of a mixture of polymers, often referred to as lignocellulose. The cellulose micro fibrils consist of an immensely strong, linear polymer of glucose. They are associated with smaller, more complex polymers composed of various sugars called hemicelluloses. These polysaccharides are embedded in an amorphous phenylpropane polymer, lignin, creating a remarkably strong com posite structure, the lignocellulosic cell wall. Wood also contains materials that are largely extraneous to this lignocellulosic cell wall. These extracellular substances can range from less than 1070 to about 35% of the dry weight of the wood, but the usual range is 2% -10%. Among these components are the mineral constituents, salts of calcium, potassium, sodium, and other metals, particularly those present in the soil where the tree is growing. Some of the extraneous components of wood are too insoluble to be ex tracted by inert solvents and remain to give extractive-free wood its color; very often these are high-molecular-weight polyphenolics.

Chemicals Extraneous to the Lignocellulosic Cell Wall

Natural Products of Woody Plants

Edward L. Schneider

Handbook of The Biology of Aging, Third Edition provides a general overview to a wide scientific audience of some of the most important topics in biomedical gerontology. The book discusses methodologies for biological aging studies and on animal models. Protein modifications with aging, special senses, circadian rhythms, and the adrenocortical axis are tacked in the book as well. Gerontologists, psychologists, health care professionals, and graduate students will find the book useful.

John W. Rowe

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