Carbohydrate as the primary product of photosynthesis has a vital role in the maintenance of life on this planet. Until relatively recently, interest in complex carbohydrates focussed on their structural role in the extracellular matrix/ cell wall of animal, plant, and microbial cells and on their role as energy sources (e.g., starch and glycogen) and struc- tural components (e.g., cellulose) in natural products. There was, however, indirect evidence that carbohydrates could play an informational role; this evidence was from the find- ing last century that plant lectins caused specific...