176 i-ENEKAL ANATOMY. 



special anatomy of these membranes, and particularly to that 

 of the peritoneum and arachnoid. 



226. Of the two surfaces of these membranes, one is gene- 

 rally free, in a healthy state, and the other adherent. The 

 free surface is shining, moist, and appears polished ; it is, how- 

 ever, covered with small villosities which become visible on 

 looking at it under water, and which the inflammatory irrita- 

 tion renders very apparent. It is to the serous membranes 

 which envelop and line them, that the organs and parietes of 

 the splanchnic cavities owe their shining aspect; wherever 

 they are without it, they have not the same appearance. This 

 free surface, every where contiguous to itself, as well as the 

 serosity.that humects it, creates a distinctness, a true isolation 

 between parts very nearly approximated; they also singular- 

 ly facilitate the motions of these parts. 



227. The other surface of the serous membranes is almost 

 universally adherent, either to the viscera or the walls of the 

 cavities; there are only some prints of the visceral lamina of 

 the arachnoid, which are free on the two surfaces, every where 

 else the external surface of the serous membranes is adherent. 

 This adhesion is on one side with the parietes of the cavities, 

 and on the other, with the surface of the viscera. The degree 

 or solidity of this adhesion generally varies. In general, 

 wherever the serous membranes are connected with a liga- 

 mentous tissue, as with the dura mater, the pericardium, the 

 aponeuroses of the abdominal parietes, the tunica albuginea of 

 the testis, &c. there this adhesion is very intimate; it is also 

 very great with the muscular and other parts, as the heart, 

 lungs, stomach, intestines, &c. ; it is much less so, in other 

 places, as where the membrane passes from an organ to the 

 walls of a cavity, and vice versa; where it forms bridles, or 

 floating prolongations that contain vessels; in the places where 

 the sub-serous cellular tissue contains fat,and, generally, where- 

 ever it is loose. 



228. These differences are of sufficient importance to de- 

 mand further attention; the consequence is, that when, for 

 Example, the uterus, the bladder, the stomach and the intes- 

 tines augment in volume, the peritoneal bridles and ambiant 



