1. (1 -> 4)-|3-D-glucans are very long linear polymers in which (1 -> 4)-B-D-glucosyl moieties are linked by inter- and intramolecular hydrogen bonding to form microfibrils. These microfibrils form the fibrillar component of most higher plant cell walls. The proportion of cellulose is very small in seed cell walls which contain large deposits of stored polysaccharides.