The first layer of fibrine thus deposited on the inner surface of the membrane forms, if it is complete, a kind of sac, in which the more serous part of the exsudation is included. But this liquid part generally contains a con siderable further portion of the fibrinous element ; and the resulting phenomena appear to depend in some measure on its amount. Thus, if the exsudation be almost wholly of plastic material, large irregular masses of fibrine are found in the cavity of th'e mem brane ; the serous fluid being only in sufficient quantity to moisten these loose coagula. If the serutn be superabundant, the fibrine may remain almost or entirely dissolved in it ; or may only be visible as a slight disturbance of its transparency, imparting to it a white colour, or forming a few scattered flakes which float hither and thither in the fluid. A medium between these two extremes is perhaps more common, in which the plastic element coa gulates in a loose irregular kind of net-work, the meshes of which enclose the serum. And with this more general precipitation there is usually a special deposit upon the peripheric or oldest layer before mentioned, which imitates its irregular or shaggy form. But as this process of coagulation is often a very slow one, the extent of lamination is by no means limited to these two layers ; five, ten, or twenty thin strata often appearing to be laid down from the fluid, one after another. In all these cases, the denser and stronger layer, in contact with the surface of the serous membrane, is the original plasma, the first which was deposited, and the earliest to be organized. Rarely the completeness of this coagulation leaves the serous part entirely devoid of fibrine, and, in respect of composi tion, closely resembling some of the dropsical fluids previously described.
Organization of the In some very fevv instances, in which the exsudation is only in a limited quantity, absorption occurs prior to the deposit of the fibrinous portion ; but after this change has once occurred, and the fluid has been separated into a serous and solid portion, the former only is susceptible of removal, the latter or fibrinous constituent being either absolutely incapable of absorption, or, what is perhaps more probable, being re moved so slowly as to be replaced by the organization of new tissues long before its withdrawal is completed. When the quantity of fibrine is small, organization is on the whole both less frequent and rapid. Still it may occur; and even where this substance is re tained in solution, the fluid containing it is susceptible of this- change.
But although the products of inflammation generally progress towards organization, yet the steps and results of this further develop ment differ very widely from each other.
In the majority of these effiisions, one of two processes occurs. In one class of cases, the free surfaces of the membrane are glued together by the coagulable lymph effused upon them ; and this cementing substance is either itself converted into a permanent structure which obliterates the cavity, or it forms a nidus or strotna in which the structure is developed.
In another set of cases, the plasma experiences a rapid development into a number of cells, floating in a thin fluid. These are termed the adhesive and suppurative forms of in flammation respectively ; or sometimes, with perhaps less correctness, the " terminations " of this process.
In some instances, however, a process similar to the first of these takes place inde pendently of adhesion. Sometimes, the plastic layer on the inner aspect of a serous mem brane ex,periences a transition into a structure which resembles areolar tissue, and presents an irregular or shaggy surface, like the fibrine for which it is substituted. In other instances, a thinner layer, with a more regular surfitce, is formed, and clothes the normal structure with a new serous or fibro-serous membrane, which can readily be peeled off from the subjacent tissue. This layer is rarely of uniform thickness, and when limited to small isolated patches forms the " white spots " which are so frequently seen in the peri cardium. In these instances, the effusion is evidently in very small amount, and probably consists almost wholly of the plastic materials of the blood, with very little accompanying serum, Another class of cases may be mentioned here which, in respect of the absence of ad hesion, are somewhat similar to this condition. They differ from it, however, in the fact of their presenting a large quantity of a serous or little fibrinated fluid, and in the very slow organization of their solid matter, which, in some instances, advances so little in a con siderable lapse of time, that we might almost doubt the occurrence of any further deve lopement. In these instances, the small amount of plastic material present is irregu larly deposited here and there in the shape of small granules of fibrine which are scattered over the surface of the serous membrane. This condition frequently occurs in the peri toneum, and has been called " tubercular peritonitis." It ofFers, however, such wide distinctions from the really tuberculous in flammation, that it is difficult to imagine that the term was ever used to express more than the shape of the deposit ; and in order to avoid the confusion caused by designating two such different diseases with one name, Mr. Simon has suggested that of " granular perifonitis," a term which avoids this ob jection, but equally indicates the peculiar form which the fibrine exhibits.
When the plastic material bas been mainly deposited on the walls of the cavity, and has included a considerable quantity of serum in its interior, an absorption of this fluid neces sarily precedes the contact and adhesion of the opposed surfaces. But in the more diffuse and irregular coagulation previously alluded to, in which the serous portion occupied the meshes or interstices of the fibrinous net-work,. the latter may become organized, and may thus form cyst-like cavities, which are perma nently filled with this fluid.