† Present address: Department of Radiation Biology and Physics, Queen's College, University of St. Andrews, Dundee, Scotland.
* An earlier account of this work was presented at the Fifth International Congress of the International Union of Crystallography, Cambridge, England, in 1960; see published abstract (Low, B. W., A. S. McGavin, and J. R. Einstein, Acta Cryst., 13, 1056 (1960)).
This investigation was supported by a Senior Research Fellowship SF-246C to one of us (B. W. L.) from the Public Health Service, in part by a Public Health Service Research Grant A1320 C from the National Institute of Arthritis and Metabolic Diseases, Public Health Service, and in part by a research grant G3347 from the National Science Foundation. We are grateful to the Watson Scientific Computing Laboratory for IBM 650 computing facilities.