Paul de Krulf has frequently served in the role of the a medical detective -- and popularized the results of his findings so that the uninitiate of the lay public could feel cognizant of what was going on in the field of medical research. This time he has taken as his goal the much-disputed subject of what testosterone, ""the male hormone"" could achieve, in raising the level of vitality in manhood. He traces the 86 years of experimentation and research -- and the findings. Today testosterone can be administered in tablet form; it boosts waning muscle power; it eases pain in certain forms of heart trouble; it relives fatigue symptoms; it renews the tissues of old men; it produces growth, -- sexual, muscular, etc, to eunchoids, retarded males, mental cases where the cause lies in male hormone huger. Its dangers and shortcoming and failures are indicated -- this is no panacea for rejuvenation. Paul de kruif writes in very human terms of the scientists who have followed the gleam; he illustrated with actual cases. The book seems however to lack the cohesion of his earlier work; it is repetitive and at times padded; and the style is almost too too jovial and smart alecky to give the materia the serious significance he desires. Certainly not a book for a general public -- young and old, male and female.