2M DIGESTIVE SVSTExM. 



touch any of the viscera within it : this, we know, is precisely the 

 same case in regard to the pleura. 



Texture.— Tho, texture of this membrane also is like that of 

 the pleura. Strip it off from any part, and it will prove rough 

 and shaggy, exteriorly, from the presence of numerous little floc- 

 culent adhesions: and this shews tlie nature of its attachment to 

 the several parts it invests; viz. by cellular tissue. But its inte- 

 rior surface is everywhere smooth, glib, and humid ; and this is 

 assignable to two causes — to the uniformity and compactness of 

 its texture, and to the exhaktion of a serous vapour, which after 

 death becomes condensed, and which we always find more or 

 less of, in the liquid state, between the different viscera. The 

 peritoneum appears to be composed of condensed cellular mem- 

 brane, interwoven with numerous bloodvessels, some nerves, and 

 many absorbents. It is extremely elastic, whereby it accommo- 

 dates itself, without corrugation, to the perpetually varying ca- 

 pacity of the cavity, as well as the frequent change of volume 

 and relative situation of many of the viscera : indeed, at certain 

 times, it must admit of very considerable extension ; e. g. in the 

 mare during gestation, and in ascites. 



Ligaments. — What are called the ligaments of the peritoneum, 

 are certain parts which in the foetus were vessels of importance, 

 but which in the adult degenerate into impervious chords, and 

 for this reason have their name altered. The anterior ligament 

 or ligamentum rotundum (originally the umbilical vein) runs be- 

 tween the peritoneum and abdominal muscles, from the umbilicus, 

 or navel, to the liver. The two posterior ligaments (consisting of 

 what once were the umbilical arteries and the urachus) pass in 

 the same manner from the navel to the bladder ; the former tra- 

 versing its sides to join the iliac arteries, the latter entering the 

 substance of the bladder at the very apex of its fundus. In the 

 young animal it generally happens that these vessels are per- 

 vious for a considerable distance ; but then their caliber is ex- 

 ceedingly reduced in size, their coats being proportionately 

 thickened. 



Use. — The principal use of the peritoneum is to secrete a se- 

 rous fluid — a fluid that exists in a vaporous state during life, for 

 the lubrication of every part of the membrane ; in consequence 

 of which those viscera that are continually moving within the 

 belly glide over one another not only without friction, but with- 

 out exciting the least consciousness of their motions on the part 

 of the animal himself. In addition to this, the peritoneum fur- 

 nishes most of the viscera with a complete external tunic, and 

 tliereby adds strength and firmness to their several textures ; it 

 attaches, and supports, and confines those viscera (within cer- 



