In these polyarticular forms the most distinctive joint deformities are those met with in the _hands_ or feet, more particularly the former. The excrescences produced are the outcome of successive _uratic deposits_. These latter when massive can scarcely be confused with any other disorder, for the superjacent skin, distended by the ever-increasing underlying uratic deposits, becomes thinned and purplish red in hue, and occasionally ulcerates. I have at present in my wards a case of this nature, and the subject hoards up the exuding “chalk” in a small bottle. Fortunately such marked examples are relatively rare, though easily recognised; but it is the less marked types that occasion difficulty in diagnosis. The point at issue of course is the differentiation of moderate-sized or small tophaceous swellings from bony outgrowths. Frequently the task is impossible of achievement without resorting to puncture, when, if anything can be withdrawn, microscopic examination may reveal the presence of _biurate_ crystals. For the rest, attention to the following points will prove helpful in enabling us to differentiate clinically between gouty arthritis and other chronic joint disorders attended by deformities:— (1) Tophi when of recent incidence are _soft_, and when of long standing are never so dense or so hard as bony outgrowths. (2) The overlying skin is thin, and through its substance the subjacent white concretions may sometimes be discerned. It may be adherent, or the seat of ulcers. (3) Uratic deposits are _not located exactly at the level of the articulation_. They do not adapt themselves to the contour or shape of the bone-ends. (4) Unlike osseous growths, they may be slightly movable in lateral directions. (5) Tophi may _soften_ or _disappear_ after exacerbations of arthritis. DIFFERENTIAL DIAGNOSIS The conditions likely to be confused with chronic polyarticular gout are osteoarthritis, rheumatoid arthritis, and the multiple arthropathies met with in affections of the central nervous system. OSTEOARTHRITIS Its chief characteristics may be summarised as follows:—It is a disease rarely met with under forty years of age. The mode of onset is generally insidious, never really acute. In this respect it contrasts with gout, the initial outbreak of which is invariably acute. Osteoarthritis attacks both sexes equally. Although it may be polyarticular, its specific tendency is towards a mono- or, more accurately speaking, oligo-articular distribution, with no marked leaning to symmetry. It has a pronounced predilection for attacking the _hip_, the _shoulder_, and the _spine_—sites rarely, if ever, attacked by gout. Unlike gout, constitutional symptoms, pyrexia and so forth, are generally absent; muscular atrophy is slight, hardly ever pronounced, likewise muscular spasm and contracture. LOCAL CHARACTERS OF JOINT SWELLINGS