The Challenge of Facts. Selected Public Health Papers of Edgar Sydenstricker

entities. The data presented in this book help explain why some dystrophies may vary in the degree of musculoskeletal involvement compared to others, since the extracellular environment of the skeleton, in addition to its biochemical factors, also is affected by biomechanical stresses that vary depending upon the age and area. Undoubtedly this combination of factors plays a role on the abnormal cellular gene expression. The papers are extremely well presented and well illustrated and vary from articles that are primarily reviews of previous work to the presentation of very concise biochemical data. The editors have obviously expended considerable effort to compartmentalize the papers in a meaningful fashion. This work obviously will become an important reference source in the future. JOHN OGDEN Department ofSurgery Yale University School ofMedicine