Two of the many conditions commonly called " rheumatism" are actual joint diseases?(I) osteo-arthritis, a nuisance but not a calamity, and (2) rheumatoid arthritis, the most crippling of all. In two others there is no joint disease: (3) primary fibrositis, a periarticular or intramuscular condition producing aching and stiffness, and (4) " psychogenic rheumatism "?a psychoneurosis affecting the...