THE SEROUS CAMTIES 137 



adhesions. In the rabbit the mesoduodenum, mesentery of the 

 jejunum, and descending mesocolon will be recognized as parts in 

 which a more typical arrangement is retained. Moreover, in the an- 

 terior portion of the abdominal cavity the peritoneum is concerned 

 not only with the investment of two large visceral structures, the 

 stomach and the liver, but also with the formation of a lining for the 

 posterior surface of the diaphragm. Thus the general condition is 

 less simple than in the region of the small and large intestines. The 

 peritoneum, passing from the dorsal wall, successively invests the 

 spleen, the stomach, and the liver, and passes over from the 

 last-named structure to the diaphragm and the ventral body- 

 wall through the coronary, triangular, and falciform ligaments. A 

 portion of the peritoneum passing between two organs, such as the 

 stomach and the liver, rather than connecting either to the body- 

 Avall, is termed an omentum or sometimes a ligament. Thus the 

 peritoneal attachments of the stomach are differentiated into the 

 mesogastrium (connecting the stom.ach with the diaphragm and 

 dorsal body-wall and divisible posteriorly into gastrosplenic and 

 phrenicospenic ligaments), the greater omentum (a broad fold 

 connected to the greater curvature and to the transverse meso- 

 colon), and the lesser omentum (passing between the lesser cur- 

 vature and the liver). Similarly, in the posterior part of the body 

 the peritoneum passes from the rectum to the urinary bladder, 

 enclosing also in the female the vagina. It is then continued to 

 the ventral body-wall as the middle umbilical fold. The falciform 

 ligament and the middle umbilical fold represent respectively the 

 anterior and the posterior ends of an originally continuous ventral 

 mesentery, these parts being retained when the rest degenerates 

 in early foetal life because through them run the umbilical blood- 

 vessels (pp. 115, 117). 



In the male, as indicated in the accompanying diagram (Fig. 81 ) , 

 the peritoneal relations of the testis are greatly modified by the 

 migration of the organ from an abdominal to a scrotal position. 

 The entire sac lodging the testis Is an evaginated portion of the 

 abdominal wall, and since in the rabbit the cavity is widely open 

 throughout life to the abdominal cavity, the lining membrane — 

 that designated as the parietal layer of the tunica vaginalis propria 

 — is continuous with the parietal peritoneum of the abdomen. It 



