=Adhesions.= The two layers of the pleura being in immediate contact, the consequence of this effusion of coagulated lymph will be an early adhesion of the applied surfaces. This is accomplished by a blending of the layers of coagulated matter in contact, and a gradual organization of the same by an extension of blood-vessels from the pleura into the new formation. At the same time that these changes are progressing, the watery part of the exudation trickles down to the most dependent portion of the cavity, and there forms a serous or sero-purulent accumulation. Adhesions are more frequent at the upper portion of the lungs, but may be found at any point, as between the inner surface and the mediastinum, or the lower surface and diaphragm; or, from repeated attacks of pleuritis, involving different portions of the serous membrane, the whole of the exterior of the lung may become united to the adjoining surfaces. The strength of the adhesions will be somewhat in proportion to their age, those of long standing requiring considerable force to break them up, and in many instances the lung tissues becoming lacerated before the attachments can be torn away. Unusual thickness of the pleura is often found at points where no adhesions exist, this being unquestionably the result of the effusion of plastic matter into the subserous tissue during an attack of inflammation. =Serous Effusion.= While in the majority of cases of pleuritic inflammation, we shall find _plastic effusions_ followed by adhesions of the inflamed with the adjoining surface, in some instances a serous or watery fluid is rapidly poured out, and, accumulating in the pleural sac, constitutes _hydrothorax_ or dropsy of the chest. The fluid in these cases may present a variety of shades of color, from a pinkish or light straw color, to a dark brownish shade. It may be transparent or opaque, and generally will be more or less albuminous. The quantity may vary from a few ounces to three, four, or five pints, or more. When in large quantity, the lung will be found more or less collapsed, shrunken, and pressed against the posterior walls of the chest and spinal column. In the general dropsy attending diseases of the heart, kidneys or liver, effusions may take place into the pleural cavities, to such an extent as to give rise to great dyspnœa from compression of the lungs. =Sero-Purulent or Puriform Effusions=, consist in the presence of a quantity of granular particles with albuminous matter, which subside to the bottom of the vessel when drawn off, and always contains floating flakes of lymph. It may be found in cases of both acute and chronic pleurisy, and, like serous effusions, may be found in large quantity.