consisting of, or containing, cells.-the substance which constitutes the essential part of the solid framework of plants, of ordinary wood, linen, paper, etc. it is also found to a slight extent in certain animals, as the tunicates. it is a carbohydrate, (c6h10o5)n, isomeric with starch, and is convertible into starches and sugars by the action of heat and acids. when pure, it is a white amorphous mass. see starch, granulose, lignin.