Abstract
The fine structure of the mass defect curve has been studied, especially with reference to the nuclear symmetry character. From the analysis it has been found possible to obtain satisfactory empirical curves for the functions L and E0 appearing in Wigner's theory. The behavior of these curves allows deductions to be made regarding nuclear shells, and binding energies of both known and as yet unknown, unstable, nuclei. About 150 masses have been computed in this way.