What is it that maintains some infections and makes them chronic? This question is particularly pertinent to a disease like pyelonephritis in which organisms often cannot be cultivated by usual methods, particularly between acute episodes. The same could be asked about Reiter's disease and other chronic or recurrent conditions which seem to start as bacterial infections.
These and related questions have occupied the attention of the editor of this volume for a number of years. During this time he has been exploring a model for pyelonephritis in rats and has been concerned with the disease in humans. These encounters have inevitably turned his attention to the problems of protoplasts, spheroplasts, and L-forms, which are the configurations assumed by bacteria that have completely or largely lost the rigid cell walls responsible for their normal shape and size.
The present volume is the result of Guze's effort to corral a group of