The Harvey Lectures for 1928-1929 cover, as in previous years, a wide range of topics. Every one of the essays is, however, stimulating to thought and representative of biologic and medical progress. The opening essay by Dr. C. M. Child on "Senescence and Rejuvenescence from a Biological Standpoint" indicates how far from realization are the hopes of any one who would change the biologic nature of the cell. Dr. Felix d'Herelle discusses the ultrafiltrable viruses, and Dr. Constantin Levaditi the treatment of the spirochetoses by metallic substances. Other essays concern nephritis, constitution and disease, calcium and phosphorus metabolism, digitalis, and tuberculosis. This series of lectures has been from the first well organized and of uniform grade.