Abstract
Summary 1. Evidence that virus disease may develop a latent state is reviewed with an account of the reports of successful activations of latent infections. 2. Nineteen instances of precipitation of latent herpetic infection in rabbits by anaphylactic shock are presented. 3. Recovery of Herpes simplex virus from rabbit central nervous system during periods of (a) quiescence, (b) chronic encephalitis, (c) spontaneous exacerbations, and (d) anaphylactically induced precipitations of encephalitis is reported.