Among the causes of burns are: steam; hot water; melted glass, wax, rubber, sugar; molten metal; red-hot metal; gas and flame; burning wood, paper, clothing; electricity; X-ray; ultra-violet ray; chemicals; acid sulphuric, trichloracetic acid, common lye; alkalis; carbolic acid; iodin; croton oil, mustard, cantharides. From these various causes there is very little difference in symptoms, course, pathology, and treatment. The molten lead burns are usually small in area, but of the third degree. The underlying tissues are often devitalized, especially around the feet, making a deep, pale, slow-healing ulcer. The same is true of many burns from electricity. The effects of X-ray burns are only seen after several days or weeks and stubbornly resist treatment. Ultra-violet ray burns may not show any effects at first, but develop symptoms in about six hours, sometimes accompanied by great pain. Such burns may be due to sunburn or powerful electric light. The epidermis contains no blood vessels, but the mucous layer has lymph spaces between the cells, draining into the lymph spaces and channels of the dermis. Nowhere in the body are nerves more abundant than in the skin. Here we have nerves of motion to the muscles of the skin; nerves of pain, temperature, and touch; forming an intricate plexus of nonmedulated fibres sending their branches upward into each papilla, and even to the mucous layer of the epidermis. Vasomotor nerves supply the coats of most blood vessels of the skin, and trophic nerves are everywhere controlling the nutrition of each part. When it is considered what a complex organ the skin really is; how delicately its parts are adjusted to the body; how extremely sensitive its nerve supply, slight stimuli bringing responses and causing reflex action in far distant organs; how many the uses of the skin (protection, excretion, expression, and sensation in various forms), it can readily be understood how great is its importance, and the far-reaching results of its serious injury. Burns are classified into three degrees: first, second and third. In every burn there are two layers of tissue to be considered: _first_, the layer destroyed—the dead flesh; _second_, the layer injured—the sick flesh. +BURNS OF FIRST DEGREE+ +Pathology.+ (1) Destruction of the cells of the horny layer. (2) Injury of the cells of the mucous layer with an excess of lymph. No blistering. (3) Congestion of the subpapillary plexus with some destruction of the hemoglobin. (4) Closing of the ducts of the sweat and oil glands. (5) Slight edema of the underlying dermis. +Clinical Stages.+ 1st stage—hyperemia and pain. 2nd stage—edema. 3rd stage—peeling and staining the skin. 4th stage—cells of the horny layer replaced by pushing upward of cells from stratum lucidum. BURNS OF THE SECOND DEGREE +Pathology.+ (1) Destruction of cells of horny layer and sometimes of the germinal layer.