MEMBRANE. 87 



edge next to the ribs, &c. where it is found somewhat fleshy. From its situa. 

 tion in the middle, this natural division is termed the midriff, or skirt, and ap- 

 pears to have been designed for keeping back the stomach and bowels of the 

 hinder part, which ai: it is, when full, press it out of shape, not unlike that of a 

 watch glass, and would, but for this barrier, interrupt the action of the heart 

 and lungs. But by the present contrivance, as we shall see presently, this 

 pressure from behind soon recedes, the midriff returns to its level, and the 

 ribs, no longer contracted towards each other by the aforesaid pressure, ex- 

 pand, thereby enabling the lungs to perform their function, of drawing in a 

 iresh supply of air. Upon this principal agent in the function of respiration, 

 see more in detail in the 35th section of this chapter. 



26. After this necessary preamble, let us proceed, as before proposed, to 

 consider the construction of 

 The Membranes, 



Muscles, 



Glands, 



Absorbents, (i. e, 1st lymphatics, and 2d lacteals,) 



Nerves.* 

 Of these the most universally dispersed over the frame, those which occupy, 

 defend, or embrace every part, are the membranes. As well behind as before 

 the midriff, not only inside, but on the outside and every part of the animal 

 are these skinny films placed, for the purpose, 1st, of keeping those parts which 

 they encompass in a compact state ; 2d, to secrete a fluid for protection (see sect. 

 21); and 3d, to prevent those parts from rubbing against and injuring each 

 other, or adhering together. The better to accomplish these purposes they are 

 admirably calculated for the secretion of a fluid, as I observed before (sect 20); 

 but whenever the property of secreting such fluid is suspended, then disease 

 begins, and according as the secretion may prevail, being either too little or 

 too much, will be the kind and quantity of disease. Hereupon may be calcu- 

 lated the importance they hold in the animal system: but of those matters I 

 have already spoken higher up. 



Membranl^!. — To appearance they are nearly transparent, web-like, and 

 of a strong texture ; some are simply film, having more or less of feeling ac- 

 cording to their uses, and are those which, beino; interposed between one or- 

 gan, or part, and another, prevent the interruption which would otherwise 

 ensue; as the midriff, for instance, which 1 have just above adverted to (see 

 sect. 31 and 35), which is the thickest of all, or the loose membrane that covers 

 the lungs and divides them into two parts, so as each may act separately (see 

 sect 32). The second species of membranes are finer, more transparent, and 

 paler than the first mentioned, and possess the quality of containing in their 

 cavities, resembling sponge, the matter deposited within them by the arteries 

 for the purpose of repairing waste and adding new flesh ; these we term cel- 

 lular membranes, from their sponge-like texture, and they are, moreover, so 

 infinitely thin as to pervade all over the solids, or fleshy parts, without being 

 in every case visible to the eye. They are nevertheless proved so to exist, 

 from the circumstance of those being greatly distended, when the subject dies 

 of being "blown," as 1 have shown lower down (sect. 35). Then, not only 

 the forehand, but the hinder quarter, even down to the hocks, become inflated 

 with the wind, which, by reason of the animals being strangled, the lungs had 

 no power to discharge, and the cellular membrane admits it into its cells or 

 .'.avities. Any one may perceive this membrane and its numerous cells to 

 advantage in a buttock of beef, or leg of mutton, after being dressed ; up^n 

 taking a slice between the fingers and straining it nearly asunder, tiic raeaj 



* For ligamenta, cartilages, tendons, &c see sect 16 17. 



