ALIMEiNTARY CANAL. 501 



pelvis, as the recto-vesical fold, the false ligaments of the bladder, and the 

 broad ligaments of the uterus. 



The Appendices epiploicce are small irregular pouches of the peritoneum, 

 filled with fat, and situated like fringes upon the large intestine. 



Three other duplicatures of the peritoneum are situated in the sides of 

 the abdomen; they are the gastro-phrenic ligament, the gastro-splenic 

 omentum, the ascending and descending meso-colon. The gastro-phrenic 

 ligament is a small duplicature of the peritoneum, which descends from 

 the diaphragm to the extremity of the oesophagus, and lesser curve of the 

 stomach. The gastro-splenic omentum is the duplicature which connects 

 the spleen to the stomach. The ascending meso-colon is the fold which 

 connects the upper part of the ascending colon with the posterior wall of 

 the abdomen ; and the descending meso-colon^ that which retains the sig- 

 rnoid flexure in connexion with the abdominal wall. 



Structure of Serous Membrane. Serous membrane consists of two 

 layers, an external or areolo-fibrous layer, and an internal layer or epithe- 

 lium. The areolo-fibrous layer upon its outer surface is rough and vascu- 

 lar, and adherent to surrounding structures; but on its inner or free sur- 

 face is dense and smooth, and deficient of vessels. The smooth and 

 brilliant surface of serous membrane is due to a distinct epithelium, com- 

 posed of laminae of cells, and flattened polyhedral scales with central nuclei, 

 like the epiderma and epithelium of mucous membrane. Henle has also 

 observed this structure, which may be demonstrated with a good micro- 

 scope, on the surface of all the serous membranes of the body, upon the 

 surface of the lining membrane of arteries and veins, and on synovial 

 membranes. 



The general characters of a serous membrane are its resemblance to a 

 shut sac, and its secretion of a peculiar fluid, resembling the serum of the 

 blood ; but the former of these characters is not absolutely essential to the 

 identity of a serous membrane ; for, as we have shown above, the perito- 

 neum in the female is perforated by the extremities of the Fallopian tubes ; 

 while in some aquatic reptiles there is a direct communication between its 

 cavity and the medium in w r hich they live. 



From the variable nature of the secretion of these membranes, they 

 have been divided into two classes, the true serous membranes, viz. the 

 arachnoid, pericardium, pleurae, peritoneum, and tunicaB vaginales, which 

 pour out a secretion containing but a small portion of albumen ; and the 

 synovial membranes and bursa, which secrete a fluid containing a larger 

 quantity of albumen. 



ALIMENTARY CANAL. 



The Alimentary canal is a musculo-membranous tube, extending from 

 he mouth to the anus. It is variously named in the different parts of its 

 course ; hence it is divided into the 



Mouth, 

 Pharynx, 

 (Esophagus, 

 Stomach, 



C Duodenum, 

 Small intestine < Jejunum, 



f Ileum. 



