Hutchinson’s views regarding the essential difference between gout and rheumatism are crystallised in his statement that in rheumatism there is an arthritic susceptibility to weather, in gout an arthritic susceptibility to diet. Osteoarthritis also seems to have been included as one of the gouty diseases, probably because _post-mortem_ examination revealed uratic deposits in the disorganised cartilage. This, however, would appear to be an epi-phenomenon, and must not be allowed to obscure the essential distinction between true gout and osteoarthritis. It is a sign of articular disorganisation of _long standing_, and is the homologue of the similar deposition of crystals, etc., already referred to as occurring in the eye as the result of chronic disease therein. _The significance of tophi_, as the touch-marks of gout, is undoubted, but even if they are detected in the eyelids or elsewhere, we are skating on thin ice if we rashly declare that a coexisting intra-ocular disorder is gouty. Most forms of iritis betray the same clinical _facies_, although the etiological causes are diverse. But in none do we find any appearances pathognomonic of gout. The argument that because a patient has tophi therefore the iritis is also gouty does not hold good, for gout does not confer immunity from other diseases, and even though we cannot prove an alibi for the diathesis, we can often in these cases also indict gonorrhœa, pyorrhœa or some other pathogenic agent. The favourite site for tophi is one in which blood-vessels are sparse; but, although the cornea is void, imbibition of blood from the marginal looped plexus of capillaries and an abundant lymph supply provide amply for nutrition, and tophi are not found in this locality. The sclerotic, however, has a meagre supply of vessels, and for some unexplained reason tophi rarely invade it. In the eyelids, on the other hand, possibly from the cartilage being rich in sodium, tophi are occasionally seen. If we accept the tophus as the one unequivocal criterion of gout, we are not justified in labelling an iritis as gouty in its absence. If we do, our diagnosis is presumptuous and not absolute. Strictly speaking, the diagnosis cannot be made. We may the more readily admit our limitations, inasmuch as they are a blessing in disguise, and suggest a further etiological search.