SEROUS AND SYNOVIAL MEMBRANES. 



539 



few weeks' or months' standing, they may 

 vary somewhat from this description by the 

 possession of a rough surface on one side, 

 which indical.es the seat of their previous 

 attachment to one of the bones of the leg. The 

 observations of Cruveilhier * have furnished 

 us with a knowledge of the stage which, at 

 least in some instances, immediately precedes 

 this condition. He has shown that, in some 

 cases, the development of these bodies occurs 

 in the subserous or rather subsynovial tissue ; 

 that their enlargement carries forward the 

 synovial membrane ; and that a peduncle is 

 thus formed, the rupture of which sets them 

 free, in the articular cavity. 



There are other cases which possibly re- 

 present a different class, and which are dis- 

 tinguished from these by the characteristics 

 of the greater number, lesser size, and, for 

 the most part, much softer consistence of 

 these bodies. Their general features have 

 long been known to anatomists, and recently 

 the minute descriptions of Bidder-)- and 

 Hyrtl J have added important, though appa- 

 rently conflicting, details concerning them. 



In the case which Bidder has narrated, 

 the morbid product was removed from the 

 knee-joint during the life of the patient, so 

 that the appearances of the synovial mem- 

 brane are necessarily wanting. The mass 

 consisted of granules, the shape of which 

 was always a flattened oval ; and their size 

 offered a similar uniformity, the length of the 

 oval being about one-eighth of an inch, and 

 this about double and treble its width and 

 depth respectively. Their surface was smooth 

 and shining, their colour yellowish-white, 

 and a viscid fluid in sparing quantity (probably 

 synovia) united them into small clumps or 

 masses. In consistence, they were softish, 

 yet highly elastic, resuming their original size 

 and shape immediately after the removal of a 

 flattening pressure. A microscopic exami- 

 nation showed them to consist of an uniform 

 substance, and to be entirely devoid of all 

 traces of organization. Their chemical re- 

 action was that of an albuminous solid; 

 viz. they were unchanged by water or ether, 

 were shrunken by the application of alcohol, 

 and were swelled out into a transparent mass 

 by acetic acid. The substances described by 

 Hyrtl differed in many important respects 

 from the preceding granules. The synovial 

 sheath of the flexor tendons was distended, 

 so as to form a protuberance above and below 

 the annular ligament of the wrist. Pressure 

 on either of these swellings alternately gave 

 rise to a predominance of the other one, and 

 was attended by a kind of crepitating sound. 

 On laying open the sheath, its interior was 

 found to be occupied by upwards of a hundred 



* Patholog. Anat. ii. 2. p. 211. 



f Henle mid Pfeufter's Zeitschrift, 1815, Band iii. 

 Ueber Entstehunp; fester Korper in den von Sy- 

 novialhaiiten gebildeten Hohlen. 



J Oesterreiche Medizinische Jahrbucher, Bd. 

 xxxix. S. 261. Anatomische Untersuchung einer so- 

 genannterHydatiden Geschwulst des Sehleimbeutels 

 cler Beugesebnen aru Carpus. 



small bodies, which in their colour and general 

 appearance seem to have greatly resembled 

 those described above ; but their consistence 

 appears to have been softer, their size less 

 uniform, varying from that of a hempseed to 

 a lemon-pip, and their flattened shape was, 

 in most instances, altered by the possession 

 of an elongated extremity, although others 

 were more globular. The sac itself exhibited 

 very interesting appearances. The tendons, 

 where they passed through it, were greatly 

 diminished in bulk. The parietal portion of 

 the sac appeared to consist of two layers, a 

 serous and a fibrous, the latter of which was 

 dense. (Probably this appearance was partly 

 due to a condensation or the neighbouring 

 areolar tissue by pressure into a membranous 

 form, similar to that seen in the sac of an 

 aneurism.) The synovial membrane, where 

 it covered the tendons, was looser than 

 natural, and had lost its smoothness and 

 polish, while in many places it had acquired 

 a villous appearance. In the subserous 

 areolar tissue, little knots were seen, many of 

 which projected into the sac, carrying before 

 them a covering of the serous membrane ; 

 others of them had rather a constricted neck; 

 and, finally, in others this constriction had 

 increased so as to form a peduncle of little 

 more than the thickness of a hair. The 

 severance of this connection brings these 

 bodies to the same condition as the granules 

 which were found free in the cavity ; but the 

 bulk of many of these was larger, while those- 

 yet in connection with the sac were uniformly 

 of small size. This larger size of the un- 

 attached bodies was also noticed by Mor- 

 gagni. The minute anatomy of both the 

 free and attached substances was the same. 

 Their surface was clothed with an epithelium 

 of angular flattened cells, and their interior 

 contained areolar tissue and fat, with a 

 grumous coagulated substance. These two 

 normal tissues, however, were not in a healthy 

 state; the fat cells were wrinkled, their con- 

 tents half solidified, almost opaque, and of a 

 sordid yellow colour ; the areolar tissue was 

 alike destitute of regular arrangement and of 

 its ordinary wavy lines ; while with all this 

 was mingled much amorphous debris. 



Concerning the mode of formation of these 

 substances considerable differences of opinion 

 have prevailed, which may justify a slight 

 notice in this place. 



The descriptions of Cruveilhier, Hyrtl, and 

 others, leave no doubt as to what is the pro- 

 cess of their development in at least a large 

 proportion of instances. These exhibit them 

 as affections of the subserous, or rather sub- 

 synovial areolar tissue ; while the circum- 

 stances under which they are found, such as 

 the arrangement of tbe deposit in small masses, 

 which are plentifully scattered over a large 

 surface, the aged and debilitated constitutions 

 in which they are chiefly present, &c., indicate 

 with tolerable clearness that they are the 

 result of disease, as contradistinguished from 

 external violence. 



But it may be doubted whether this expla- 



