  We discuss Einstein's field equations in the presence of signature change
using variational methods, obtaining a generalization of the Lanczos equation
relating the distributional term in the stress tensor to the discontinuity of
the extrinsic curvature. In particular, there is no distributional term in the
stress tensor, and hence no surface layer, precisely when the extrinsic
curvature is continuous, in agreement with the standard result for constant
signature.
