ORIGINAL LECTURES.

CLINICAL LECTURES

ON

DISEASES OF THE SKIN.

ILLUSTRATED BY COLOURED ENGRAVINGS.

By WM. JENNER, M.D.

Physician to University College Hospital, and to the Hospital for Sick Children.

LECTURE I. (a)

GENTLEMEN,-Students constantly leave the Hospital without being able to name, or recognise with certainty, the most common diseases of the skin. They seem to be deterred even from attempting to acquire a knowledge of these diseases by their barbarously sounding nomenclature, their innumerable divisions, and countless subdivisions. There is no class of ailments, however, with which, for the patient's sake as well as for your own success, it is more desirable that you should be precisely acquainted; and for these among other reasons:-Diseases of the skin are exceedingly common, and those who suffer from them know at once that they are the subject of them, and can appreciate, as well as you can, every change in them. They are unsightly; and even those who are the plainest in other people's eyes will strive hard to preserve what they consider their beauty unimpaired. A large number of the diseases of the skin are very tractable; at the same time, some are almost or quite incurable; and to confound the one group with the other is a serious matter for the patient, as well as for your own reputation. So much attention has been paid to affections of the skin, and the local disease is so patent to direct treatment, that the therapeutics of this branch of pathology is decidedly in advance of that of any other. Remember, however, that to avail yourself of the labours of others-of the vast materia medica at your command-you must be able, not only to give a name to the disease under your eye, but also must know by what name it has been described by others. Again: some skin diseases are merely the outward signs of constitutional derangements, derangements of which the patient complains but little, or, it may be, not at all, and for which he certainly would not think of seeking Medical advice; and yet of derangements which you must detect, or all your endeavours to cure the superficial ailment will be made in vain.

All diseases attended with an eruption on the surface, or with any change from the healthy structure, function, or colour of the skin, are skin diseases; and all abnormal states of the hair and nails, inasmuch as the hair follicle is one of the structures of the skin, and the nail a modification of the epithelium, are ranked in the same category. But then, in a few of the diseases attended with an eruption on the surface, the constitutional disease is so profound, and the skin-affection so insignificant a part of the ailment, that it seems unwise longer to speak of them at any length among diseases of the skin. I have already directed your attention to particular cases of small-pox, scarlet, typhus, and typhoid fevers, and I shall now, therefore, only enumerate these diseases and others of a like kind in their place. In other diseases of the skin, the subcutaneous tissues are so deeply involved, that the skin affection constitutes a very small part of the local disease, and the propriety of classing such affections with ordinary skin diseases is more than questionable. The same is true in regard of certain diseases attended with deviation from the healthy functions of the skin.

I trust the fact of my treating of Diseases of the Skin as a special group will not lead you to consider them as differing essentially from diseases of other organs, for they owe their origin to the same kind of causes, agree with them pathologically, run a like course, and have like terminations. In re(a) During the summers of 1855 and 1856 I delivered at University College Hospital a short series of clinical lectures for the purpose of making the Student practically acquainted with diseases of the skin. The Lectures themselves were illustrated by cases, and the cases compared in the theatre with casts, and published and unpublished drawings, so that the value of these latter might be duly appreciated. The Medical Times and Gazette having proposed to give plates printed in colours of the genera described in the Lectures, I have been induced to agree to their publication, and, at the same time, to add somewhat to the course, so as to render it more systematic and complete than was possible in a clinical theatre.

Vol. XXXV. No. 901.-NEW SERIES, No. 310.

ference to the majority of diseases of the skin, as of other diseases, you have to consider the constitutional state that disposes to the affection, the local condition that renders the skin susceptible, so to say, of the special disease, and the locally acting cause which determines the occurrence of the disease. Diseases of the skin are as much a speciality as are diseases of the lungs, heart, or liver, but not more so. Like disease of all other organs, diseases of the skin are disposed to by certain constitutional states, and by diseases of other parts, and, like all other organs, the skin, when extensively diseased, leads, perhaps through the medium of the blood, to abnormal conditions of parts not anatomically related to it. For practical purposes, the genera and species of the diseases of the skin that you need to remember are really neither very numerous nor very difficult to recognise, and separate from each other. As this is to be a course of Lectures on the subject, I must have an arrangement; but, as the Lectures are to be essentially clinical, I shall have to deviate from my arrangement, seeing that it will not always be possible to obtain, at a given hour and on a particular day, cases to illustrate the points that at that time ought, if we adhered to our arrangement, to come before us. So, having laid down an order for the arrangement of diseases of the skin, I shall have to select diseases from that order irregularly, always keeping in view, that my object is to enable you, at the end of the course, to distinguish practically from each other, and to treat all the more ordinary forms of diseases of the skin, to name them, and to understand what others signify by the same name, or by what name they have described the same affection.

No doubt, theoretically considered, the best and primary division of diseases of the skin is into essentially local diseases and essentially constitutional diseases. And this division would be practically the best, if we could arrange all diseases of the skin under the one or the other head; because you would then know, by the position assigned to any particular disease, its most important pathological character, and also the most important point to be kept in view in its treatment. But this arrangement is impracticable. Our knowledge of diseases of the skin is not precise enough to enable us to refer them severally to the one or the other of these two heads.

We can say that itch is essentially a local disease, and small-pox a constitutional affection; but where shall we place miliaria, seeing that the miliary eruption is excited by some abnormal conditions of the perspiration, e. g., such as occurs in rheumatism? Again, where shall we group urticaria? Urticaria is sometimes excited by certain articles of diet; that is to say, during the digestion of these articles a material enters the blood, or the blood is so modified as to excite the disease of the skin called urticaria. Now, does the fact of the blood being contaminated in this way from the food constitute a claim for urticaria to be ranked as a constitution affection? It manifestly does so. But, then, the application of certain irritants to the skin produces a disease identical, anatomically, with that induced by the ingestion of substances to which I have just adverted. So that urticaria may be a purely local affection, or the local manifestation merely of a constitutional state. The inconvenience of separating two cases of what is one genus, when considered anatomically, is manifest. If the diseases of the skin of parasitic origin, and those induced by the external application of direct irritants, be excluded, there are very few of them which are not more or less dependent on constitutional derangement. Nay, even parasitic diseases seem to take little hold on the constitutionally sound, and many of those primarily excited by local irritants are kept up by constitutional abnormities.

A second method of dividing skin diseases into orders is founded on the supposed pathological nature of the local affection, e.g., inflammation-hypertrophy, the orders thus formed being divided into genera according to the structure supposed to be first affected, e.g., the sudoriferous ducts, the sebaceous follicles, the hair follicles, the epithelium. But the fact is, that our knowledge is not yet sufficiently advanced to enable us to determine in the majority of cases either the primary pathological process, or the part of the skin, anatomically considered, first affected. So that this division, which when first proposed to us charms by its appearance of scientific accuracy, is in the present state of medicine practically impossible. The time may come when it will be as useful as it is theoretically pleasing, but to-day is not that time.

The division of skin diseases which I shall adopt is sub