100 ANATOMY OF THE RABBIT. 
digestive tube, and is therefore considered as divided into corres- 
ponding parts. In many cases the relations of these are greatly 
complicated by secondary adhesions. In the rabbit the mesoduo- 
denum, mesentery, and descending mesocolon will be recog- 
nized as parts in which a more typical arrangement is retained. 
Moreover, in the anterior 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 
small and -large mtestines. - The 
peritoneum, passing from the dorsal 
wall, successively invests the spleen, 
the stomach, and the liver, and is 
reflected from the last-named struc- 
ture to the diaphragm and the ventral 
body-wall through the coronary, 
triangular, and falciform liga- 
ments. Its gastric portion is differ- 
entiated into the mesogastrium 
Fic. 55. Diagram showing the rela~ (phrenicosplenic and __ gastrolienal 
tion of the testis to its investments: 
a.i., inguinal ring; c.e., caput epididy- ligaments), the greater omentum, 
midis; cr., cremaster muscle; dd, ductus 
deferens; zg, gubernaculum; mes, mes- and the lesser omentum. Similarly, 
orchium; ptv, and vtv, parietal and 
visceral layers of the tunica vaginalis in the posterior part of the body the 
propria; pv, cavity of the vaginal*pro- 
Bs eae a a peritoneum passes from the rectum 
to the urinary bladder, enclosing also 
in the female the vagina. Ic is then reflected to the ventral body- 
wall as the middle umbilical fold. 
In the male, as indicated in the accompanying diagram (Fig. 55), 
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— 

