This name was chosen, firstly in consequence of its etymological signification, which implies the idea of exudation; secondly, because the blood condition underlying the diathesis is probably similar to, if not identical with, that concerned in the production of rheumatism and gout; and thirdly, because the vulgar name salt-rheum, so commonly used in this country, embraces the affections under consideration.

The first point to be considered is, whether the condition which we have called the rheumic diathesis really exists; second, we must consider its nature; and third, the propriety of assigning to it the three affections mentioned.

Argument in support of the existence of the rheumic diathesis would hardly seem to be necessary were it not for the fact that it is denied in toto by the Vienna school; a school whose many valuable contributions to dermatology entitle its views to our highest respect.

Looking to the past, we find that from early times in the history of medicine there has been a more or less prevalent belief in the existence of a general condition intimately connected with certain cutaneous affections, and which was recognized by the Greeks under the name of psora. This term, though frequently used with great vagueness, still represented a prominent idea, and corresponded to the "scabies" of the Romans (Celsus), the affection to which the name eczema is to-day applied.

Paulus AEgineta included psoriasis, as well as eczema, under the term psora.

Rhazes describes two kinds of "scabies," the moist and the dry, and places "pruritus" in intimate connection with them. He attributes them ail to "humores adustos" and originating "ex sanguine et phlegmate falso." The "scabies" here mentioned was equivalent to the ancient psora or modern eczema, and the "pruritus" probably corresponded to the lichen or papular eczema of the present day.

Leaving the distant past and coming to the dawn of modern systematic dermatology, we find Plenck * using the term "scabies" with very great looseness, making no less than eight varieties, of which but one, "scabies verminosa," + corresponds to the affection now called by this name. The "scabies capitis" of Plenck, however, plainly includes eczema and "est critlca evacuatio humoris acrimoniosi, qui per glandu-las capillitii excernitur."

Later we find that, instead of the Roman "scabies" or eczema being the principal feature of psora, the modern scabies or itch proper, by a curious confounding of terms, became its chief synonym. The itch, then, became the representative of psora, and, although by most regarded as a local affection, was still by many believed to be of constitutional origin. This view was especially elaborated by Hahnemann,++ and carried to such extravagant lengths that reaction was the natural consequence. The idea of the constitutional nature of the itch was finally overthrown by Re-nucci's ** demonstration that the acarus scabiei was unquestionably the cause of the affection, and from that time the idea of psora as a constitutional disease no longer existed in the minds of the majority. Mod-scabies was the parasite which destroyed the diathetic claims of the ancient and more respectable psora, and hence the German notion of the local nature of all these affections.

Turning to England, we find the original idea prevalent in the early part of this century. Parr, | speaking of psoriasis, says, "It is more strictly the dry itch, which, in compliance with authors, we have mentioned under the last article" (Psora). "It is always apparently connected with some disorder in the constitution, often with gout and rheumatism. The seminium of the disease is apparently in the consti-tutioi

Later this use of the term psora became corrupted, as in Germany; and we find Plumbe * confounding it with parasitic scabies. The constitutional nature, however, of the affections which it formerly included, is still maintained in England.

* Doctrina do Morbis Cutaneis, p. 41, Vienna), 1770.

+ Est Scabies. in qua Vermiculi seu Acari reperiunfor," p. 42.

** Die chmnischen Krankheiten. Dresden u Leipzig, 1828.

** Gras, Recherches sur l'acarua, Paris, 1834. | London Medical Dictionary, American edition, Philadelphia, 1819.

In France we find a cutaneous diathesis, distinct from syphilis and scrofula, accepted almost without dissent; this diathesis is commonly known as the "dartrous" and, synonymous with dartre, we find a revival of the ancient term herpes.

Hardy + believes that the term dartres may, with propriety, be applied to a very natural family of cutaneous affections, possessing many common characteristics, to which he alludes. In general terms he describes those subject to this diathesis as "in appearance enjoying all the attributes of good health, but who are yet in a peculiar state which cannot be considered perfectly sound. Their integument is habitually dry, and perspiration is diminished. The skin is often the seat of lively itching, even in the absence of eruption. The appetite is generally well developed, and it is well known that the dartrous eat a much greater quantity of food than other patients in analogous conditions. Another important peculiarity is the extreme sensibility of the skin, and the facility with which it is influenced by the lightest and most fugitive impressions. Sometimes general excitement, alcoholic excess, watching, use of coffee, of certain kinds of food; sometimes a local excitement, irritating frictions or the application of a plaster, will give rise to an eruption, often ephemeral, and not dartrous in character, but which reveals a particular predisposition of the economy, and the existence of a latent vice which needs but a favorable occasion to manifest itself." To this diathesis Hardy ascribes eczema, lichen, psoriasis, and pityriasis.

Gigot-Suard, ++ under the title of herpetism, includes the affections just mentioned, and, in addition, a few others whose claims to this position appear to me to be somewhat doubtful.