This book reports a symposium on fundamental concepts of disease from the viewpoint of the cytologist, cellular physiologist, microbiologist, virologist, and immunologist. It is divided into three parts: materials and methods, current concepts of the host-parasite relationship, and discussion. Each paper is followed by an excellent discussion and an exhaustive bibliography. Microphotographs with use of the electron and light microscopes are abundant. This small volume contains the current basic knowledge available in the field of infection and immunity and is intended for the research worker, for whom it should be invaluable. The clinician who eventually uses these laboratory discoveries should also benefit by reading this little book, in bringing himself up to date in current basic concepts of disease.