OP THE SEROUS MEMBRANES. 147 



CHAPTER II. 



OF THE SEROUS MEMBRANES. 



180. The membranes, membranae, are soft, broad and thin 

 parts that line the cavities, envelop the organs, enter into the 

 composition of a great number of them and constitute others: 

 they differ greatly from each other in their texture, composi- 

 tion, action, &c. 



181. The serous membranes, membranx serosse, vel suc- 

 cingentes, so called because they contain a great many serous 

 vessels in their thickness, are humected by a liquid analogous to 

 the serum of the blood, and because they furnish tunicks to many 

 organs, form a system or numerous genus of membranes closed 

 on all sides, adhering by one surface to the surrounding parts, 

 loose and contiguous to themselves on the other, serving to 

 isolate certain parts, to facilitate their movements, and result- 

 ing from a very simple modification of the cellular tissue. 



182. Confounded for a long time with the parts to which 

 they are attached, the serous membranes have been particularly 

 distinguished from other parts and studied in their ensemble 

 by Bonn,* by Munro,t and particularly by Bichat.J 



183. The serous system comprehends membranes which, 

 by their numerous points of similarity, form a very natural 

 genus, in which, however, there are sufficient differences to 

 mark several divisions expedient. In relation to their situa- 

 tion, and to the more or less unctuous liquid which humects 

 them, they are divided into serous membranes, properly so 

 called, or serous membranes of the splanchnic cavities, and 

 synovial ; the latter are again divided into those of the articula- 



* Be continuationibus mtmbmnarum. Amst. Batav. 1763. 

 \ .7 description of all the bursae mucosse, 6?c Edinb. 1788. 

 t Traite des Membranes. Paris, an. viii. 



