OF THE SEROUS MEMBRANES in GENERAL. 149 



different forms we have just examined, are often united in 

 the same membrane. In the enveloping serous membranes, 

 like in those which are found about the heart, lungs and testi- 

 cles, there is always a spot on the surface of the organ deprived 

 of this serous envelope; it is through this spot that the vessels of 

 the organs penetrate, or that the organ itself is attached to the 

 surrounding parts. This part, freed from organs covered with 

 serous membranes, is sometimes considerable, at others, very 

 narrow. In some instances the viscus is removed from the 

 parietes which contain it, arid is attached or suspended by a 

 fold of the serous membrane which forms what is called a 

 bridle or membranous ligament: this disposition is no excep- 

 ception to what we have just said. There is always a part of 

 the organ, not covered by' the membrane throughout the whole 

 extent of the surface to which the fold formed by the latter 

 adheres. Besides this first kind of folds or plaits, the serous 

 membranes present prolongations, that float more or less loose- 

 ly in the cavity they form, and which most commonly depend 

 on their visceral layer, but which sometimes belong to the 

 others : the epiploon, the appendicoe epiploicoe for the perito- 

 neum; the fatty plaits observed in the pleura on the sides of 

 the mediastinum, for this latter membrane; thesy no vial fringes 

 for the articulating capsules, are all examples of these pro- 

 longations. These latter always contain cellular tissue, gene- 

 rally fatty, within their substance: it is here also that the 

 membrane presents most vessels. 



185. All the serous membranes have two surfaces, one 

 free, the other adherent. The latter is flaky, and holds to the 

 cellular tissue, to ligaments, tendons, cartilages, &c. Its de- 

 gree of adherence to these different parts is more or less great: 

 a loose cellular tissue sometimes produces it, while elsewhere 

 as on the cartilages, it adheres closely. There is a multitude 

 of intermediate degrees between these two extremes, as may 

 be observed when adhering to ligaments, muscular fibres, 

 tendons, &c. The free surface of the serous membranes is 

 everywhere contiguous to itself: it is the interior of a kind 

 of bladder that these membranes resemble. This surface, at 

 the first glance, appears perfectly smooth and polished: but 



