This book consists of articles by a number of competent scientists on major special problems of aging. The list of the authors and chapter headings will give a good general idea of the authorship and the scope of the book: William Crocker, aging in plants; H. S. Jennings, senescence and death in protozoa and invertebrates; L. O. Howard, aging of insects; T. Wingate Todd, aging of vertebrates; Clark Wissler, human cultural levels; Louis I. Dublin, longevity in retrospect and in prospect; A. E. Cohn, cardiovascular system and blood; E. B. Krumbhaar, lymphatic tissue; A. C. Ivy, digestive system; Jean R. Oliver, urinary system; T. Wingate Todd, skeleton, locomotor system and teeth; F. D. Weidman, aging of the skin; A. J. Carlson, the thyroid, pancreatic islets, parathyroids, adrenals, thymus and pituitary; Edgar Allen, female reproductive system; Earl T. Engle, male reproductive system; G. V. Hamilton, changes in personality and psychosexual phenomena