becoming thin and transparent, smooth on their external surface, and furnishing a serous secretion. Not unfrequently, inflammatory action in this tissue terminates in suppuration; and the pus, secreted by the membrane, accumulates in the most dependent part of the cavity. By collections of matter, whether serous, sero-purulent, or purulent, within a serous cavity, the functions of the contained viscera are deranged, much impeded, and in many instances morbid actions are excited in them. The inflammation, whether it terminates in resolution, or proceeds to serous effusion, adhesion, or purulent secretion, is attended with constitutional disturbance, and the symptoms are proportioned to the original intensity of the action, and the extent and kind of its termination. The effusion of lymph, and consequent adhesion, is, however, in many circumstances, a highly salutary process, as in wounds and injuries of the hollow viscera: effusion of their contents being thereby prevented, and the patient being saved from the danger attending violent inflammation of those cavities and their coverings, caused by the escape of a greater or less quantity of irritating extraneous matter. Purulent collections also, in the solid internal viscera, are thus allowed to discharge themselves externally. The nature, symptoms, and consequences of inflammation of serous membrane, will be more fully considered under the diseases of particular parts. OF INFLAMMATION OF TISSUES COMPOSING THE ARTICULATIONS. Inflammation of the synovial surface occurs in consequence of wounds, bruises, or sprains, and often from exposure to cold; from the latter cause, the knee and elbow joints most frequently suffer, as they are generally more exposed to its influence, and not so well covered with muscular substance as the others. Constitutional diseases, such as certain fevers, are followed sometimes by effusion of serous fluid into joints. Purulent matter is also deposited in joints during certain forms of suppurative fever; and this is attended by rapid change of structure.