174 GENERAL ANATOMY. 



stance, had even indicated the analogy that exists between 

 them. As regards their pathology, Sauvages and M. Pinel 

 had already established an order of inflammation for that of the 

 diaphanous membranes, but one comprehending the inflamma- 

 tions of the stomach, of the intestine, bladder, and epiploon, as 

 so many genera. Various pathologico-anatomical observations, 

 those of T. G. Walter on the peritoneum, in particular, had 

 shown that this membrane, like all other serous membranes, 

 could be affected throughout its whole extent, and independ- 

 ently of the subjacent parts; finally, Dr. Carmichael Smith had 

 noted with exactness, the identity of the inflammation of all 

 the diaphanous membranes, when Bichat gave his exact and 

 complete description of the serous membranes, and particu- 

 larly of the arachnoid. Descriptions of some of these mem- 

 branes have been given since;* but little, however, has been 

 added to what our celebrated anatomist has said; more has 

 been added to ther pathological history. 



224. The serous membranes of which we are now speak- 

 ing, are situated in the cavities of the trunk, which they line; 

 they there invest the most important organs, those that are the 

 most essential to life. These membranes are distinct and se- 

 parate from each other; their number is but small; viz. 1st, 

 the peritoneum in the abdomen, where it invests more or less 

 perfectly the greater part of the organs of digestion, that are 

 contained in this cavity, and rather less the genital and urinary 

 organs; 2d and 3d, the two pleuras, and 4th, the pericardium 

 in the chest, where each one of these membranes is restrained 

 to a single organ, and to the parietes of its cavity; 5th, the 

 arachnoid in the cranium, and in the spinal canal; 6th and 7th, 

 in man only, the tunica vaginalis. 



The extent of these membranes, collectively, is very consi- 

 derable, and greatly surpasses that of the skin. The perito- 

 neum is the greatest of these membranes, its extent being 

 equal, at least, to that of all the others together. 



225. The general description of the serous membranes, 



* See JLangenbeck. Commentarium, de structure, peritonceci. ect. cum tabu- 

 Its. Getting, 1817. L. Rolando. Osservazioni sul peritonea et sulla pleura 

 in mem. della real dead, de/le srienze. Tom. xxiv, Turin, 1820, 



