Although exact science does not demonstrate that poisonous matters are eliminated through perspiration, still some very noted men, like Ortner and Goldscheider, are convinced of it. Arloing contends that the perspiration of even a healthy man is toxic, whereas Queirolo admits this to be so only in the case of sick persons. We shall also be able to realize the great importance of the skin as an eliminating organ for toxic products after a little consideration on the origin of skin diseases, which we believe are due to two principal causes: Firstly, the invasion of microbes into the skin after a diminution of its resistance, which, in turn, is dependent upon the condition of its nutrition by the blood. This is the external cause. Secondly, by the elimination of toxic products which are formed in the body and then pass through the skin. These may have originally been introduced from the outside, either by food or by drugs, or they may have been produced in the body through products arising from certain glands, such as the thyroid, sexual glands, etc. The waste products of metabolism, such as uric acid, may also be included in this category. This is the internal cause of skin diseases. Both of these causes may stand in relationship; thus the existence of the second may favor the development of the first. For the subject now under consideration the second cause is more important, and we will say a few words on the matter as showing the importance of the skin as an eliminating organ for toxic products. We may frequently see persons who are affected by eruptions on the skin after eating certain kinds of food, as oysters or strawberries; and especially after eating oysters which have not been absolutely fresh. In our own case, and in many others which we have observed, an eruption of acne on the face has followed the eating of cheese. A similar state of things may result from taking certain drugs; thus, after bromine or iodine very often acne may be observed on the face. This interesting fact we have experienced personally and have noted in patients who have taken thyroid tablets in certain quantities, which also contain iodine. If we examine acne eruptions we find in them certain microbes, such as the bacillus of Unna, etc. In gout, which is caused by the retention of uric acid, skin diseases are very frequent. Sufferers from Graves’s disease, in which there is, as has been so often mentioned, a hyperactivity of the thyroid gland, have very frequently cutaneous eruptions, including acne, and often also a very irritating pruritus. Also in diabetes, in which thyroid hyperactivity plays a prominent rôle, it is not so much the sugar as the factor I have referred to, which is the cause of the great frequency of skin diseases. Here also a number of toxic products are eliminated through the skin.