Erratum.
On page 1426 of the report "Association of parvoviruses with rheumatoid arthritis of humans" by R. W. Simpson et al. (30 Mar., p. 1425), a portion of the text beginning on line 18 of the first full paragraph in column 3 was incorrectly printed. It should have read, "We were unable to detect 24-nm particles in brains of normal mice from our colony or mice intracerebrally inoculated with extracts of synovial cells from patients with noninflammatory degenerative joint disease (DJD). More conclusive evidence for the identity of RA-1 as a parvovirus comes from our recent success in demonstrating that CsCl gradient fractions containing the infectious 24-nm particles can be extracted for a single-stranded DNA which is approximately 4.5 kilobases in size."