JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 807 not more than 5%, of dermatologic patients will be found to possess internal disturbances which are relevant to their skin diseases. Derma- tologists, of course, must be cognizant of the possibility that the patient may have a systemic disorder in which the skin is participating, or indeed, that the patient may ½oncomitantly have some unrelated in- ternal disorder whose detection, cardiac or pulmonary disease, for instance, might be even more important than the skin manifestations. I am, however, proposing that the extensive and expensive work-up more or less as a matter of routine when there is no clue to suggest the possibility of internal disease is an action that is calculated, perhaps unconsciously, to be more helpful to the doctor than the patient. Once the biopsy is taken the average hospital has little more to offer in the way of studies directed to the skin itself with the exception of such elementary procedures as patch testing for contact allergy, photosensi- tivity and the like. If one can't study the skin in depth, one can at least call on the resources of the internist and request an evaluation of the heart, lungs, kidney, pancreas, bone marrow, blood, adrenals--the diagnostic possibilities are impressive and are very helpful in quieting the physician's anxieties concerning his credentials as a real doctor. The pressing need is for a quantitative methodology which will portray and reveal the dynamic disturbances in the skin. It is not enough to classify and identify the disorder on the basis of its gross and microscopic attributes. We need to know a great deal more about functional derangements. The changes are often subtle and well below the level detectable by the eye. After a single modest ultraviolet ex- posure or even after so transient and trivial a reaction as a histamine wheal, the skin may remain abnormal for many months, though there's nothing to suggest this by appearance alone. Of course, one needs sensitive methods to appreciate these subtleties in the case of ultra- violet light, a suitable reflection meter to demonstrate the persistence of venous congestion revealed by an elevated amount of reduced hemo- globin after whealing, a means of measuring skin temperature with great accuracy to show that the affected site does not react in quite the normal way when it is again subjected to histamine whealing. The great French dermatologist, Gougerot, wrote a little volume, all but unknown in this country, dealing with the "invisible" or "silent" dermatoses relating to skin diseases which were hidden from view. He clearly appreciated that skin disease may involve more than meets the eye. Now I shall reveal the meaning of my cryptic title, "Blind Man Dermatology." I believe that the golden age of dermatology is still

508 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS before us. To mine the treasure buried in skin disease will require the virtual elimination, though not necessarily the enucleation, of the eye as a diagnostic instrument. The point of this essay is that dermatology will enter the privileged domain of modern medicine when a blind man will not in the least be compromised in the practice or investigation of skin disease. I foresee the day when a blind dermatologist will have a good deal more "vision" than the best sighted of us now possess. Our happy blind man will rely on exteroceptive techniques that add immensely to what can be learned by looking. It is the utilization of instrumentation, gadgetry if you will, that will lead us to this kingdom. What kind of measurements will provide the information we avidly desire ? Galileo said, "Measure what you can measure, count what you can count, if there is no measurement, invent one." To specify meas- urements that will teach us more about the behavior of normal and abnormal skin requires an understanding of the complex nature of skin. It is in fact not a homogeneous organ it varies from region to region and from the surface downward. It is not a simple tissue but a com- pound one with adnexal specializations such as sweat glands, hair, and sebaceous glands. It is divided into horizontal compartments, the epidermis, dermis, and subcutaneous tissues, each with its unique and different functions. It contains nerves, vessels, lymphatics, all in complex relationships. It is, in fact, not an organ but a series of organs, not a species but a genus. A quantitative analysis of these diverse functions is entirely within reach of modern methodology. Each structure has attributes which can be characterized dynamically, that is, in terms of the function subserved. It would be tedious to do more than merely list some of the tools and methods which might provide a "profile" of the skin in health and disease. To name some of the more obvious activities which are susceptible to measurement: (1) Skin blood flow, by determining clearance of a freely diffusable ion such as radio-sodium. (2) Lymphatic flow t•y monitoring the rate of disappearance of radio-iodinated albumin. (3) Epidermal replacement time by thymidine labelling of DNA in the nuclei of the germinative layer. (4) Skin permeability by measurement of water diffusion rate utilizing electrical hygrometry alternatively, one can determine the penetration and absorption of radio-active substances from the skin