Bazin ** separates the dartre or herpetis of Hardy and the majority of French writers, into two principal diseases, which he calls respectively dartre and arthritis, and between which he endeavors to draw distinctions, which are in many cases so delicate as to be hardly appreciable. He adds to the list of affections a number which appear to be accidental rather than essential to either of these diatheses.

In Italy, where cutaneous diseases have been studied with great zeal and scientific care, we find a general acceptance of the herpetic and arthritic diatheses.

Coming finally to-America, we find a very widespread belief in the existence of a constitutional condition manifested by certain cutaneous eruptions, which have received the common name of salt-rheum. It is this diathesis, equivalent to the dartre of Hardy, the herpetism of Gigot-Suard, the herpetis and arthritis of Bazin, and Italian writers, and the psora of the ancients, for which I propose the term Rheumic as a designation.

The existence of this diathesis cannot be considered completely proved, as the very nature of the case renders an absolute demonstration impossible. In this, as in most other theoretical questions in medical science, we are obliged to form our opinions by the preponderance of probability on one side or the other, and the ability of the theory to explain the observed phenomena. In favor of this diathesis, we have the concurrent opinions of many intelligent and experienced observers, running through long periods of time, and by its acceptance a means of explaining many occurrences which would otherwise be inscrutable.

* Practical Treatise on the Diseases of the Skin, fourth edition. London, 1837. + Lecons theoriques et pratiques sur les maladies de la peau. Paris, 1860. ++ L'Herpetisme. Paris, 1870. ** Lec. theoriq. et cliniq. sur les aff. cut. de nat arth. et dart. Paris, 1868.

The second question, which requires consideration in this connection, is the nature of the Rheumic diathesis. This is not simply a matter of theoretical interest, but is of the utmost practical importance from a therapeutic point of view, since a correct understanding of the nature and etiology of the affections depending on it enables us to conceive and apply rational methods of treatment.

The older views upon this subject are not of much value, and even when we come to the present century we find very little clearly formulated. The English writers, as a rule, favor the idea that it usually depends upon the condition which gives rise to gout. Schonlein held that it, or at least one of its manifestations (psoriasis), was due to uroplania (an excess of certain urinary ingredients in the blood). This view Hebra expressly condemns. Hardy attributes the diathesis to a peculiar vice of the constitution, of the nature of which he is ignorant; Bazin, so far as his arthritides are concerned, to the same general blood-conditions which predispose to inflammation of the joints, both rheumatic and gouty; Gi-got-Suard to uric, sometimes to oxalic acid. It will be seen, then, that all the decided opinions which have been expressed, concerning the nature of the diathesis, by those who believe in its existence, are one in idea if not in words, and imply the existence of some materies peccans as the efficient cause of its manifestations. The views above stated are in the main based upon clinical observation, with the exception of Gigot-Suabd's,* which derives additional weight from the results of experimental investigation (detection of uric acid in the scales and secretions in these affections, and the induction of similar cutaneous lesions, by the ingestion of uric and oxalic acids). My own view, derived from observation, study, and experiment,+ harmonizes with those mentioned. It may therefore be formally stated that the affections pertaining to this diathesis are, in all probability, due to the accumulation in the blood of an excess of certain excrementitious substances, and presumably those which are also efficient in the causation of gout and rheumatism, with perhaps the addition of a few others whose relations to morbid conditions have not as yet received much attention. Although it is far from being susceptible of demonstrative proof, it is more or less probable that the following are the noxious agents, namely: uric acid, lactic acid, oxalic acid, cretin, creatinin, and possibly others. The first, fourth, and fifth of these are always derived from pre-existing albuminoid substances; the other two sometimes from albuminoids, and sometimes from substances belonging to the amylaceous and saccharine groups, and all of them represent either steps or side-products of the processes which bring about the metamorphosis of food in tissue, and that again into substances ready for excretion. Our present knowledge of physiological chemistry will not enable us to trace the ex-act processes and successive steps which lead to the formation of these bodies, but I think it will warrant the assertion that the general process is.

* of oil. and l'Uricemie. Park, 1875.

+ In the blood of two out of three psoriasio patients I found oxalic acid by dialyz-ing the serum. A dilute solution of chloride of calcium was placed in the outer vessel, and the result was a crop of octohedra, dumb-bells, and "spherites" of oxalate of lime. 9 one of oxidation. In other words, that albuminoids (e.g., roast-beef) entering the body as food, finally leave it as urea, mainly through the in-strumentality of oxidation, and, if the oxidation of the received albuminoids is incomplete, we have a diminished proportion of urea, and an increased proportion of uric acid, etc. This condition may be conveniently denominated, after Bence Jones,* one of suboxidation.

This incomplete oxidation appears to be, to a certain but limited extent, a normal condition, and suboxidized products are found in very small proportion in healthy blood, and ready for removal by the kidneys; and it is only when they accumulate unduly that they prove harmful. Some of these bodies are themselves, or form in the blood, compounds which are less soluble than the urea, and are not so readily excreted, and hence tend to accumulate. This accumulation occurs whenever renal action is deficient, although the production of the uric acid, etc., may be in normal quantity. Or, on the other hand, overaccumulation may occur from overproduction, even when the kidneys are removing from the system the usual proportion of these excreta.