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Since closed lines of {\it accidental} electronic degeneracies weredemonstrated to be possible, even frequent, by Herring in 1937, no furtherdevelopments arose for eight decades. The earliest report of such a nodal loopin a real material -- aluminum -- is recounted and elaborated on. Nodal loopsemimetals have become a focus of recent activity, with emphasis on otherissues. Band degeneracies are, after all, the origin of topological phases incrystalline materials. Spin-orbit interaction lifts accidental banddegeneracies, with the resulting spectrum being provided here. The geometricphase $\gamma(C)=\pm\pi$ for circuits $C$ surrounding a line of such degeneracycannot survive completely unchanged. The change depends on how the spin isfixed during adiabatic evolution. For spin fixed along the internal spin-orbitfield, $\gamma(C)$ decreases to zero as the circuit collapses around the lineof lifted degeneracy. For spin fixed along a perpendicular axis, the conicalintersection persists and $\gamma(C)=\pm\pi$ is unchanged.

Accidental Degeneracy in k-space, Geometrical Phase, and the Perturbation of $\pi$ by Spin-orbit Interactions