This volume surveys the chemistry, biochemistry, biosynthesis, metabolism and pharmacological properties of lectins. Lectins, which are most commonly found in plants, are widespread natural products with striking biological activities. Their specific ability to recognise and bind to simple or complex saccharides facilitates their role as effective information protein molecules. As agents of cell-to-cell recognition, lectins promote symbiosis between plants and specific nitrogen-fixing soil bacteria. As natural defensive molecules, they can protect plants against predators such as bacteria, fungi and insects. As part of our diet, lectins are powerful exogenous growth factors in the small intestine and influence our health, the digestive function and the bacterial ecology of the alimentary tract. Lectins are also important research tools in preparative biochemistry and cell science.