The evidence outlined would indicate that chronic rheumatoid arthritis may well be the result of a multiple mutant infection. The hypothesis is in line with the clinical course of the disease which, at the onset, may have all the earmarks of an acute infection (the streptococcic phase) before lapsing into the usual chronic form. Remissions, separated by shorter or longer periods of intermission, may be the clinical manifestations of the intricate immunological relationship of the streptococcic-dissociation forms,—the micrococcic-diphtheroid phase.

Up to two years ago, we could not satisfactorily explain why the serum of arthritic patients frequently reacted to a variety of apparently unrelated micro-organisms. The percentage of staphylococcic fixations in our records has always been high. Others have reported a variety of agglutinins for streptococcus hemolyticus as well as streptococcus viridans, for pneumococci and staphylococci.

If we were actually dealing with a specific, immutable micro-organism with stable immunogenic properties, the course of the disease should not deviate from that of other acute infections,—that is, recovery, if the system is able to use its reactive defensive forces effectively, or death, in case it is overwhelmed by the extreme virulence of the invading organism. But if we have a streptococcus capable of dissociating into microbic forms that are less resistant to the immune mechanism, we feel that the natural tendency of the host would be to encourage such a metamorphosis. The bacteriological records of the twenty-one cases outlined support this hypothesis,—the active forms always yielding streptococci; the moderately active, micrococci, either alone or with diphtheroid bacilli; the less active, diphtheroid bacilli; and, finally, the inactive or sclerotic forms being culturally sterile.

In concluding, we feel that, through a clear understanding of the mechanism of the immunological processes to which the human system resorts in bringing on these bacterial metamorphoses, we may some day have the main basis of a rational therapy for such chronic ailments.