The classification of chronic arthritis is a problem that has interested students of medicine for many years. Twelve years ago, L. F. Barker1published a comprehensive review of the subject in which he said: Despite the real progress which has been made, it must be confessed that the arthropathies are still veiled in deplorable obscurity; and, as we shall see, the dimness, while due chiefly to our inability as yet to look at the processes from an etiological viewpoint, is to some extent dependent upon an intervening dust-cloud of terminology. Dr. Barker's remarks still hold true today. The etiology of many cases of chronic arthritis is still unknown, and the terminology for the various types is still in a state of confusion. During the last four years, we have studied 612 cases of chronic arthritis in the Cornell Clinic. As our familiarity with the disease has increased, we have