AGES. PHIVATE. PUBLIC. TOTAL

to 2 yrs. . .

Total . . .

Comparing this table wiLh the preceding one it will be seen that the largest number of cases in any period of five years was that observed between the âges of 20 and 25 years, where there were 88 cases, the largest number in the preceding table being between the âges of 25 and 30. There is also seen to be a large number between the âges of 10 and 20 years, which gave 157 cases, or nearly 33 per 100 of the entire number. It will be also noted that in

19 instances it was recorded that the éruption had begun by or before five years of âge, and in nearly half lhe cases the éruption had begun by or before

20 years of âge. It will also be seen, however, that in a certain number of instances the éruption may firsl develop even at an advanced period of life, two cases being recorded as first appearing between 65 and 70 years of âge and two cases between 60 and 65 years of âge. The total number, however, first developing after the âge of 50 years is very small, hardly 4 per cent, of the entire number.

It is a little curious to note that while in the period between 10 and 15 years of âge the females are considerably in the prépondérance, during the next five years the males are greally in excess, and during the period between 20 and 25 years of âge there were 60 males to 28 females ; a possible suggestion miglit be drawn from this in regard to the effect of the later development of the sexual functions in males than in females.

Appendice

Taking thé décades of life, we fmd that in 31 instances the éruption flrst developed during the flrst decade, in 157 instances in the second decade, 152 in the third decade, 68 in the fourth decade, 34 in the flfth decade, 15 in the sixth decade, and 4 in the seventh decade. These facts appear quite opposed to the statement of Neumann (1), who asserts that the éruption generally flrst appears about the sixth year of life.

The earliest period at which the disease manifeste d itself was in a male, in the case of a young gentleman 17 years of âge, in whom the éruption hâd existed since he was weaned, before he was two years old. The youngest female was in a giii already mentioned, seen at the âge oftwo years, seen soon after the development of the éruption. Wilson (2) States that he has observed the disease at the âge of three months, his next youngest patient being 2 1-2 years of âge. He States also that he has known psoriasis to make its flrst appearance at 85 years of âge, and also in another patient at 73 years of âge. Kaposi (3) has seen an eight months old child with psoriasis, the falher also havingthe same disease severely.

The natural history and termination of psoriasis is a subject of very considérable interest and one upon which as yet very little light has been thrown. We hâve already seen from the preceding table that it may begin at any period of life, although in almost one half the cases the éruption was found to begin before the âge of twenty years. Having once begun, the disease shows itself to be one of the most rebellious of ail affections of the skin, tending to remain indefinitely, with little if any inclination to spontaneous recovery. Beginning early in life it may persist, in spite of active and prolonged treatment, even to advanced âge, although aftér middle life it often becomes less pronounced and in certain cases may become confined to a few lésions giving little annoyance. In a certain small proportion of cases it will seem to disappear even without treatment and to remain absent for varying periods, perhaps entirely. Such cases, however, are extremely rare, and even appear to dépend on some radical change in the mode of life or on a change of abode. A prolonged résidence in a warm climate will sometimes sufflce to completely arrest the disease, but it may again develop when the patient returns to a colder or more changeable climate. There does not seem to be any favorable influence exerted on the disease by puberty, the éruption manifesting itself quite as severely during and after that period as before ; indeed, in some instances the disease seems to be aggravated thereby.

Little can be stated in regard to the antécédent conditions leading to the disease, it making its appearance most uuexpectedly under the most diverse conditions of life and under the greatest possible variations of circumstances ; not only will it appear after exhaustive diseases and in those debilitated by various excesses, but it cornes equally in subjects who are apparently in the very besf health and enjoying ail the éléments of a healthy and proper life. A study of the historiés of the cases here analysed fails to diseover any single cause or element or even combination of causes or éléments to which the disease may be attributed ; although, as will be mentioned later,

(1) Neumann. Lehrbuch der Haulkrankheiten , Wien, 1873, p. 259.

(2) Wilson. Lectures on Dermatology, 1871-3, London, 1873-1876.

(3) Kaposi. Pathol, und Therap. der Hautkr., Wien, 1883, p. 394.

Appendice

several distinct types of the éruption may be made out, as found in those exhibiting the scrofulous, gouty, and rheumatic diatbeses.

The éruption of psoriasis is seen clinically to develop ip various manners, and with quite different degrees of severity. In some very young subjects, even, it appears as quite a sudden outburst, affecting simultaneously or in rapid succession the various parts of the body and extremities ; in other instances a few spots appear here and there, and develop but slowly, taking very considérable time before a large surface is affected ; in some instances the éruption remains confined to a particular locality, as the scalp or backor chest for some considérable period, often for years, and then from unknown causes more or less suddenly develops so as to involve very much of the surface.

However or whenever the éruption began, the analysis of these cases shows it to hâve been most chronic and rebellious, lasting in many instances even during the entire life of the patient in varying degrees of severity.

The following table exhibits the duration of the disease before the patient came under treatment :