Intimate molecular contact at joint interfaces is essential for the extremely localized surface forces to result in adhesion exceeding the cohesive strength of the joined materials. Liquids, however viscous, are perhaps a more important class of adhesives in biology than in any other field. Attention is focused on the spreading of well-defined liquids over rigid or coherent phases of potential biological interest. The contact angle (T) of liquids on solids provides an inverse measure of liquid spreading. Rectilinear plots of cos T vs liquid surface tension (L) define the critical surface tension of wetting (Lc) for each solid. Direct, simple correlations exist between Lc and solid surface composition. Wetting and adhesion can be completely changed by adsorbed films, even monolayers; adsorbed water, for example, can markedly decrease Lc. Wettability properties and Lc concept are pertinent to current adhesional and biomedical problems. Coupling agents have a potential role in bioadhesion. (Author).

Adhesion in Biological Systems summarizes the knowledge of adhesion in the presence of moisture, a condition required in almost all biological systems. Organized into four parts with a total of 17 chapters, this book begins with the principles of adhesion in biological systems. Then, it describes the various biological adhesives, as well as the adhesives for soft and hard tissues. Scientists in a number of fields, including physics, chemistry, zoology, botany, engineering, medicine, and pharmacy, will benefit from this book.

This vol\.Dl\e of Advances in Experinental ~dicine and Biology is based on an Arrerican Chemical Society SympositUII entitled: "Surface Chemistry of Biological Systems", which took place in New York on September 11-12, 1969. Thanks to the special photo offset process used by the publishers, the papers are appearing very soon after their presentation, and at a lower cost than usual. These advantages are appreciated by the scientific community. As the title of the vol\.Dl\e indicates we have attempted to bring the scientific approach and techniques of surface chemistry to the complex problems of biological systems. Two previous sym posia in this field have been published, one in the Journal of Colloid and Interface Science (24:1-127, 1967) and the other in the Journal of General Physiology (52:187S-252S, 1968). The previous publication outlets, a chemical and a biological journal, help to emphasize the interdisciplinary nature of the material and also the appropriateness of the choice of Advances in Experinental Medicine and Biology for the C1.lr'rent symposium.

Using scanning electron microscope techniques, the author examined the succession of microorganisms which constitute the marine microfouling community in Monterey Harbor, California, upon stainless steel substrates. He found that solitary diatoms appeared during the first 4 hours and became numerous by 48 hours of immersion. They were followed by colonial diatoms which appeared during the first 24 hours and by hydroids and bryozoans during the first 96 hours. Bacteria first became evident upon substrates which had been immersed for 48 hours. A well-established community, including, metazoa, and many unidentified forms was formed during the first 3 weeks of immersion. Observations of microfouling upon aluminum, brass, and copper substrates were obscured by the formation of a thick crust, possibly of corrosion products.

Many creatures use adhesive polymers and structures to attach to inert substrates, to each other, or to other organisms. This is the first major review that brings together research on many of the well-known biological adhesives dealing with bacteria, fungi, algae, and marine and terrestrial animals. As we learn more about their molecular and mechanical properties we begin to understand why they adhere so well and with this comes broad applications in areas such as medicine, dentistry, and biotechnology.