Abstract
A new analysis is presented of the results obtained by Borrmann and Hildebrandt on anomalous transmission in a crystal subject to a thermal gradient. Penning and Polder's theory failed to explain the observed intensity decreases. It is pointed out that a simple fanning out of the lattice planes without curvature does produce an effect on the wave fields, contrary to Penning and Polder's conclusion. Machine calculations using Taupin's differential equations exhibit substantial agreement with experiment.