Section Iv. of the Pericardium.

The pericardium is subject to the same affections as other serous membranes, including inflammation, adhesions, effusions or morbid growths.

=Inflammation= of the pericardium or pericarditis, is characterized by an unusual dryness of the surface, with injection of the vessels in the early stage, while at a later period a layer of plastic lymph will be found adhering to the surfaces. The deposit may be limited to some small portion, or be distributed over the whole inner surface of the membrane and upon the exterior of the heart, giving them the appearance of having been smeared over with some sticky substance. Often the surfaces are rough or villous in appearance, like the mucous membranes of the intestines. Irregular calcareous patches are sometimes found in old chronic cases, developed within the thickened portions of the membrane.

=Adhesions= may also form between the surfaces in contact. The whole cavity may in this manner become obliterated, or bands of adhesion may be found here and there.

=Effusions= may be found in the pericardium, as in other serous cavities. When the result of pericarditis, the fluid will often contain floating shreds of lymph. Sometimes the fluid will be found highly albuminous, and again bloody or mixed with pus. This effusion may have taken place so early as to have prevented any adhesion of parts; or it may not have commenced until union had taken place at certain parts, when, from the distension of the sac, these bands may be found greatly elongated, and stretching across the cavity in various directions. When the effusion is but part of a general dropsy, it will be clear, while the surfaces of the membrane will be smooth and destitute of evidences of inflammation. In quantity, the fluid found in these cases may vary from a few ounces to a pint or more.

Blood may sometimes be found filling the pericardium, either from a wound of its walls, rupture of the heart, or from the bursting of an aneurism. In scurvy, purpura, etc., small patches of extravasated blood may be found in its walls.

=Morbid Growths.= The more common of these, found in connection with the pericardium, are cancers. They are usually secondary in their appearance, and generally will have first developed in the mediastinum.

Fibrous or cystic tumors have been noticed in a few rare cases, while tubercles of the miliary form, are not uncommon within this membrane.