The skin is one of the chief clues to the adrenal personality. The relation between the adrenal and the skin dates way back in the evolutionary scale, for adrenalin has been isolated directly from pigment deposits in the epidermis of frogs. Skin pigment bears a direct relation to the reaction of the organism to light, especially the ultraviolet rays, to the radiation of heat, and hence to the fundamental productions and consumptions of energy by the cells. So the gland of energy for emergencies writes its signature always all over the skin. In an adrenal personality, the epidermis is always slightly, somewhat, or deeply pigmented. The pigmentation is due to a dark brown deposit lightly or thickly scattered over the skin. With the general diffuse pigmentation or darkening there are often the black spots, the pigmented birth marks, or the lighter ones of freckles. The latter signify some permanent or transitory adrenal inadequacy in the past, ante-natal or post-natal, of the individual, and presage the same in his future. These spots have been frequently observed to appear after an attack of diphtheria or influenza. There seems to be more tuberculosis among those who have them than those who do not. We therefore say that diphtheria, influenza and tuberculosis stand out as adrenal-attacking diseases, which have a greater power to kill, cripple or hurt those with defective adrenal constitutions than others. The hair of the adrenal type is characteristic: ubiquitous, thick, coarse and dry. It is prominent over the chest, abdomen and back, and has a tendency to kink. Often its color is not the expected: an Italian's will be yellow, a Norwegian's jet black. It has been stated that most red-haired persons are adrenal types. Such persons also have well-marked canine teeth which is another adrenal trait. They also have a low hair line. When the adrenal type has a properly co-operating pituitary and thyroid, he possesses a striking vigor, energy and persistence. With a fortunate combination, he develops into a progressive winning fighter, arriving at the top in the long run every time. Brain work is pretty well lubricated in the well-compensated adrenal type. Brain fag is closely associated with, if not dependent upon, adrenal fag, particularly of the cortex. Brain tissue and adrenal cortex tissue are near relatives, and a normal human brain never develops without a normal adrenal cortex. The adrenal type with an hypertrophied adrenal cortex is always efficient.