The anatomy, physiology, and general hygiene of the skin, have been considered in the first part of this work, and hence space need not be devoted to this part of the subject in this connection.

Many popular errors are prevalent respecting diseases of the skin, which originated at a time when the diseases of this portion of the body were very little understood. Modern investigations in this branch of medicine, through the aid of the microscope, have brought to light many interesting facts which explain much that was formerly very obscure. Among the numerous popular errors with reference to this class of diseases, one of the most common is the idea that all eruptions of the skin indicate an obscure state of the blood. While it is true that many diseases arise from morbid conditions of the blood, this is by no means universally the case; in fact, the majority of skin diseases are distinctly local in character. The skin is not affected by morbid conditions of the blood more frequently than are the liver kidneys, lungs, nervous system, and other parts of the body. Another error which prevails very extensively, is the idea that internal maladies of a serious character are likely to occur from the "striking in" of eruptions of the skin. We have frequently been asked by patients sufering from troublesome eruptions, whether it would be safe to cure the disease, the impression being that the eruption would occur upon the mucous membrane of the stomach, bowels, or lungs, or that some serious internal malady would be developed. The opinion of those who have had the largest experience in the treatment of skin diseases is decidedly opposed to this theory; and it is probable that there is no more reason for thinking that an internal malady might be developed by curing a disease of the skin, than the contrary; namely, that disease of the skin might result from curing some internal disorder. It is probable that in most, if not all, of the instances in which internal disease seems to result from disorders or eruptions of the skin, the relation of the two is wholly due to coincidence.