ointment morning and evening; or a lotion of the hyposulphate of soda, in the proportion of half an ounce to seven ounces of water, with which the affected surface should be bathed two or three times in the course of the day. The external application of mercury, whether as an ointment or a lotion, will seldom fail to succeed. As regards internal remedies, when the patient perspires in excess, and is out of health, quinine, with the mineral acids, may be advantageously given; but in other cases the arsenite of potash will prove a more appropriate remedy, by its action on the skin. Although pityriasis versicolor is not, I believe, ever a truly syphilitic affection, we nevertheless sometimes find it co-existing with certain syphilitic eruptions, as psoriasis palmaris or plantaris. In such a complication, we should do well to treat the latter constitutionally, while at the same time we endeavour to reduce the parasitical disease by one of the preparations of mercury, rather than by sulphur.

Icthyosis.

General characters.

CHAPTER IV.

ICTHYOSIS.

THE last of the squamous affections to be described is icthyosis, a curious disease, when seen in well-marked examples. The name is derived from a fancied resemblance of its scales to those of a fish, being peculiarly disposed, like so many small squares; but instead of presenting an imbricated arrrangement, more nearly approach those of a Saurian reptile. They are very thick, generally of a muddy or greenish, and sometimes of an almost black colour from exposure; they are especially developed in certain situations, as the knees, loins, and abdomen, and occasionally, in females, about the circumference of the nipple. The vicinity of the hips and ankles is more or less always involved. Little or no pain is experienced; and as the scales are detached, the surface is left of a whitish hue. A good illustration of icthyosis is afforded in the following instance of S. B., a girl 14 years of age, admitted an in-patient at the Skin Hospital, October 8th, 1864, under Mr. Startin. The scales covered every part of the body, except the soles of the feet and the palms of the hands, where the skin was only rough; they were also absent on the ball of the thumb and the upper lip. Their greatest development was attained in such situations as the hips and elbows; but the neck, back, and outer side of the limbs, showed the complaint in a severe form. The large scales were

irregularly fissured, and some of them curled at their margins. Thickest at the knees, they existed in large flakes on the abdomen and the thighs. The forearms,. on either aspect, were covered with dark rectangular scales, which became circular or oval towards the wrist, and slightly depressed in their centre. Usually congenital, icthyosis is never contagious; and in every case should be regarded rather as a malformation than a disease. According to Simon and Rayer the scales are com- Chemical composition posed of hypertrophoid cuticle. In a case that was of the recently under treatment at the Skin Hospital, I was scales. enabled, without difficulty, to collect a sufficient quantity for analysis, which Dr. Marcet kindly undertook. The results, he gave, are as follows:

"The principal points of interest in my analysis are the large proportion of ash, insoluble in water, consisting mainly of lime, magnesia, and iron (91 per cent. of the whole ash is insoluble), and the absence of chlorides and phosphates. There is also a large quantity of fat present.

100 parts of the dry scales contain

"Substances insoluble in water consist chiefly of lime and magnesia, apparently combined with organic matters, as the ash evolves carbonic acid when treated with hydrochloric acid. There is also some iron present."

Comparing this with the previous analysis of the skin, the proportion of fat in the latter, 11.32, is not widely different from that found in the icthyosis scales, 13-88 per cent. It is, however, in the inorganic or mineral matter that the distinction is most evident, being 1.63 per cent. in the one, compared with 8.55 per cent. of the other. From these results it would follow that icthyosis

was something more than a mere excess of cuticle, being rather a special morbid growth.

Although the distinctive characters of icthyosis are sufficiently apparent, there is another and more common form of the disease, termed congenital pityriasis and icthyosis, which represents the intermediate grade or link between the general pityriasis alluded to in the last chapter, and icthyosis in its perfect type. The scales are thinner, and more abundantly diffused and spread over the trunk and limbs than in true icthyosis, although the transition between the latter and congenital pityriasis is frequently so gradual, that it is impossible to draw the line of demarcation absolutely between them. The complaint, of which I am now speaking, is invariably congenital; and as such, it differs from congenital psoriasis and lepra in not being developed, as far as I have seen, at the time of puberty, and in one instance only, was it delayed as late as the second dentition. The most usual period for its first manifestation is from the third to the sixth month, and seldom is it deferred beyond the first year. It commences generally on the scalp and face, sometimes on the loins, and extends from thence over the entire surface, and varies from one to two or more years before its development is completed. In some of the worst instances of its occurrence, it is associated from birth with a deficiency of the eyebrows and eyelashes, and in cases less pronounced, these may be but partially present. Although, at its origin, the face is commonly involved, the disease, in its progress, sometimes appears to forsake this part, and finally settles on the back, and front of the legs. The patient's garments or bed clothes, as in psoriasis inveterata, will be constantly covered with numerous scales, which are regenerated almost as soon

as shed. The whole skin feels unusually rough and thickened, not excepting the hands and feet; and one distinguishing element of the complaint to be often noted, consists in that absence of perspiration, which, in cases of severity, would seem to be complete, the skin retaining its dry character even in the hottest day. As might be anticipated, the condition of the patient in congenital pityriasis and icthyosis is dependent, in no slight degree, upon the seasons-the disease being found to yield to the influence of warm weather, while, on the other hand, it is readily affected by the cold. In winter, or in a piercing wind, the patient is pretty sure to suffer, particularly on any surface exposed, as the hands and face, which become red and chapped; or, should he afterwards approach the fire, or become otherwise heated, the same parts tingle and smart. Sometimes the feet, around the heel, become fissured and painful, or the patient may experience much distress from the friction of the scales at the groin. It is stated that the subjects of icthyosis are, more than others, predisposed to such complaints as inflammation of the lungs, or diarrhoea; but the evidence on this point, in a given number of cases, shows the supposed liability to be the exception rather than the rule; indeed, patients with icthyosis possess quite an average share of good health, and it is yet a mooted point how far the disease may tend to shorten life.

the sexes.

In 35 cases of congenital pityriasis and icthyosis which Relative frequency have come within my notice, 16 were to the male and between 19 to the female-a result at variance with the conclusions of most continental writers, who remark upon the special frequency of icthyosis in the male. Instances are not uncommon of congenital pityriasis and icthyosis affecting both sexes in the same family, or leaving