When a new "progress" series appears in the medical and scientific literature, there is always concern that, if a need exists, it may not be met by the proposed annual volume. The issuance of the fourth annual Progress in Medical Genetics signifies that the series has been well received and has found a useful niche in the midst of our information explosion.
One is always curious as to who will be chosen to write a scholarly topical review. In some areas there are numerous choices; in others the choice narrows to one person or group of persons working together. The selection here has been unusually good, both in the past and in the present volume. The eight articles in the present volume combine accurate information with readability. The subjects are "Disorders of the Thymus and Other Lymphoid Tissues," R. D. A. Peterson, M. D. Cooper, and R. A. Good; "Genetics