Etching patterns in high purity zinc

Servi (1958) has observed certain ridges on an otherwise smooth surface produced by the action of a special etching agent on zinc. He interprets these ridges as showing the course of dislocation lines pre-existing in the specimen, suggesting that accumulated solute near the dislocation lines has made the metal more etch resistant. No other interpretation seems probable, but Servi confesses to being unable to interpret certain features in his second picture, which appears to show a 'Frank-Read source' in operation.