Phlegmonous inflammation is the active inflammation of the cellular membrane, one illustration of which is a common boil. The four principal symptoms are redness, swelling, heat, and pain; and then appears a conical, hard, circumscribed tumor, having its seat in the dermoid texture. At the end of an indefinite period, it becomes pointed, white or yellow, and discharges pus mixed with blood. When it breaks, a small, grayish, fibrous mass sometimes appears, which consists of dead, cellular tissue, and which is called the _core_. There are certain morbid states of the constitution which lead to local inflammation, subsequent upon slight injury; or, in some cases, without any such provocation, as in gout, rheumatism, and scrofula. One of the first results of the inflammation, in such cases, is a weakening of the forces which distribute the blood to the surface and extremities of the body. It is generally admitted that in scrofulous persons the vascular system is weak, the vessels are small, and because nutrition is faulty, the blood is _imperfectly organized_. The result is failure in the system, for if nutrition fails, there may be lacking earthy matter for the bones, or the unctious secretions of the skin; the sebaceous secretion is albuminous and liable to become dry, producing inflammation of the parts which it ought to protect. Disorder of the alimentary canal and other mucous surfaces are sometimes reflected upon the skin. We have occasionally observed cutaneous eruptions and erysipelas, when evidently they were distinct signs of internal disorder. Inflammation may be internal as well as external, as inflammation of the brain, lungs, or stomach, and it is frequently the result of what is called a _cold_. No matter how the body is chilled, the blood retreats from the surface, which becomes pale and shrunken, there is also nervous uneasiness, and frequently a rigor, accompanied with chattering of the teeth. After the cold stage, reaction takes place and fever follows. The sudden change from a dry and heated room to a cool and moist atmosphere is liable to induce a cold. Riding in a carriage until the body is shivering, or sitting in a draft of air when one has been previously heated, or breathing a very cold air during the night when the body is warm, especially when not accustomed to doing so, or exposing the body to a low temperature when insufficiently clothed, are all different ways of producing inflammation.