Harry Baker and Rosalind Ridley have done an admirable job in assem bling this collection of articles that describe the methodology frequently used to study a group of CNS illnesses often referred to as the "prion diseases." Research on prions and the disorders that they cause has progressed relatively rapidly over the last decade since the discovery of the prion protein (PrP) that allowed the application of modem molecular biological and genetic tools. The power of these techniques is awesome and their use in deciphering the once mysterious prion diseases has brought a wealth of new...