22 



DISSECTION OF THE DOG 



It will be observed that the whole length of the colon is provided with a 

 short mesentery (mesocolon) which is not entirely independent of the mesentery 

 of the small intestine. The caecum, unlike the rest of the large intestine, does 

 not possess a mesentery. Peritoneum is reflected from it onto the terminal 

 part of the ileum, to the side of which it is closely applied. 



Peeitonjeitm. — The interior of the abdominal wall and the surface of the 

 abdominal viscera are covered more or less completely by a serous membrane 



m, longissimus dorsi — _ 



Vena cava caudalis- 



m. obliquus 

 abdominis externus' 



m. obliquus 

 abdominis internus ~ 



m. transversus abdominis 

 Colon descenden* 



m. rectus abdominis. 



Flo. 7. — Transverse section of the abdomen on a level with the fifth lumbar 

 vertebra. Sections of the small intestine are not named. 



known as the peritoneum. Like the other serous membranes of the body, the 

 peritoneum is a completely closed sac in the male. In the female, a small 

 opening at the abdominal end of the uterine tube establishes an indirect 

 communication between the peritoneal cavity and the exterior. As in the 

 case of serous membranes in general, the peritoneum consists of a part lining 

 the wall of the cavity — the parietal peritoneum (peritonaeum parietale) — and a 

 part covering the viscera contained within the cavity, the visceral peritoneum 

 (peritonaeum viscerale) ; but, unlike other serous membranes, the visceral 

 peritoneum and its connections with the parietal peritoneum is very complicated 

 because of the number and disposition of the abdominal organs. 



