In pregnancy, the teeth suffer particularly because of disturbances of the endocrines. The saying, "A tooth for every child," is said to have its equivalent in every language. The bicuspids and second permanent molars erupt around puberty, when profound readjustments are going on among the glands of internal secretion. They consequently suffer with their abnormalities or divergences from type. The teeth thus furnish a good deal of information concerning the distribution of the balance of power among the hormones. THE SKIN The skin is influenced in its color, moisture, hairiness, texture, fat content and disease vulnerability by the endocrines. The question of color is very interesting, for it is probably the expression of the blending action of the different internal secretions. Davenport, the American student of heredity and eugenics, has shown that neither white nor black skins are either perfectly white or perfectly black, but are mixtures in various proportions of black, yellow, red and white. The exact percentages of the pigments in each particular skin, can be determined by means of a rotating disc. Thus a white person's skin may have the following composition: Black 8% Red 50% Yellow 9% White 33% The composition of the skin of a very black negro may be: Black 68% Red 26% Yellow 2% White 7% Now the fact that in Addison's disease in which the adrenals are destroyed there occurs a coincident increase in the black in the skin, and other evidence pointing to adrenal implication in dark complexioned white people, as well as in those possessing pigmented spots, seems to indicate the adrenals as controllers of the black and white factors. Davenport has concluded that there are two double factors for black pigmentation in the full-blooded negro which are separately inheritable. The determinants of the red and yellow have still to be worked out. The moistness of the skin, as perspiration, depends upon the number and activity of the sweat glands. It varies with the water content of the body, the state of the vegetative nervous system, and the body temperature. Thus the skin of the hyperthyroid and the subadrenal is soft and moist, because of their antagonistic effects upon the sympathetic system. The subthyroid and the hyperadrenal have dry and harsh skins for the same reason, if no other glands intervene. However, in both of the latter, if there is a persistent thymus, the skin will retain the bland quality of adolescence.