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

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS surface by a variety of techniques employing gas flow chambers, scintil- lation counters, etc. (5) Reparative activity after injuries ranging from simple Scotch Tape removal of the horny layer to full thickness excisions. (6) Quantitative responses to physiologic and pharmacologic agents which elicit characteristic responses such as sweating, whealing, blanch- ing, and erythema. (7) Responses to allergenic and irritant stresses viz. blistering produced by cantharidin, pustules to croton oil, necrosis after acids and alkalis, erythema to solvents, etc. (8) Thermal, mechanical and radiation responses. (9) Biochemical and histochemical analysis of scales, epidermis, dermis, etc. (10) Physical measurements of hygroscopicity of the horny. layer, "porosity" of the dermis, elasticity, thermal contraction, conductance, and impedance. To these ten can be added, in logarithmic proportions according to one's lust for measurement, other items whose characteristics can be assessed without the use of the human eye. I hope to be alive when the first blind medical graduate applies for residency training in dermatology if he is as confident as I now am that sightlessness will be an inconvenience rather than a insuperable disability, the golden age will have begun.