SEROUS AND SYNOVIAL MEMBRANES. 



535 



devoid of fibrine, and, in respect of composi- 

 tion, closely resembling some of the dropsical 

 fluids previously described. 



Organization of the effusion. In some 

 very few 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 effusions, 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 stroma 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 experiences 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 surface, 

 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 ta 

 avoid the confusion caused by designating 

 two such different diseases with one name, 

 Mr. Simon has suggested that of " granular 

 peritonitis," a term which avoids this ob- 

 jection, but equally indicates the peculiar form 

 which the fibrine exhibits. 



When the plastic material has 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. 



In most instances, the serum having been 

 absorbed, and the walls of the cavity having 

 been united by coagulable lymph, the latter 

 becomes slowly organized into a substance 

 which resembles areolar tissue, but contains 

 comparatively little of the yellow fibrous ele- 

 ment. Cotemporaneously with this change-,, 

 vessels are developed in the mass by a series 

 of processes, which, in all probability, closely 

 approximate to those of their formation in 

 the embryo. The resulting structure occu- 

 pying what was previously the cavity of the 

 serous membrane, effectually prevents the re- 

 petition of such an effusion ; although there 

 is no reason to believe that it confers an ab- 

 stract immunity as respects the inflammatory 

 process. 



The suppurative inflammation of the serous 

 membranes frequently offers, in its symptoms 

 or causes, few differences from the adhesive 

 variety ; but the formation of pus is sometimes 

 discoverable at so early a stage of the dis- 

 order, as to render it doubtful how far it may 

 not be considered, not so much a mere form or 

 termination of the disease, but an inflamma- 

 tion sui generis. Where pus has been re- 

 ceived into the bloodvessels, and circulated 

 with their contents, large collections of this, 

 fluid are sometimes seen in these tissues } 

 these are, however, to be distinguished from 

 the suppuration which occurs primarily as. 

 the result of an inflammatory process. In the 

 latter case, the cavity of the inflamed serous, 

 membrane is usually lined by a soft, irregular, 

 and membraniform exsudation, resembling the 

 wall of an abscess, to which the altered tissue 

 may, under these circumstances, be fairly com* 

 M M 4 



