in all organisms. The similar X-ray diffraction diagrams of ramie and other fibrous celluloses support this. The subtle differences in the structures of different celluloses may, however, never be fully characterized. The only hope lies in the refinement with electron diffraction data, provided that a significant increase in the amount of data can be realized.Acknowledgment. This work has been supported by the National Science Foundation (Grant No. CHE7727749).Supplementary Material Available: Tables II (most probable models after initial cycles of refinement for space group P2i), IV (Cartesian atomic coordinates of the parallel structure), and V (comparison of observed and calculated structure factors for the parallel structure) (10 pages). Ordering information is given on any current masthead page.