Technical Abstract: Cellulose properties and structure are reviewed, with a primary focus on crystal structure and polymorphy. This focus highlights the conversion from cellulose I to cellulose II, which converts the molecules to being all parallel to each other in the crystal to being antiparallel. This has been controversial for many years. To reinforce the antiparallel arrangement of cellulose II, its correspondence with small fragments of cellulose, namely methyl cellotrioside and cellotetraose, is demonstrated by highly similar powder diffraction diagrams. A new drawing was prepared for this work that compared calculated diffraction patterns from the three crystals. Using calculated data allowed identical crystallite sizes to be utilized. Molecular models, from cellobiose to crystals of realistic sizes were mentioned.