446 DISSECTION OF THE PIGEON. 



liver, slitting it up and washing out the contained blood. Note 

 the openings of the hepatic veins, and follow them with a seeker 

 into the liver. Follow the vena cava bach, behind the liver, 

 to the point where it is formed by the union of the right and 

 left iliac veins. 



2. The veins of the kidneys. 



The veins in connection with the kidneys are 

 best dissected in specimens injected from the 

 femoral vein. Their relations may, however, be 

 determined in an uninjected specimen by slitting 

 them open and following them with a seeker. 



The kidneys are a pair of elongated three-lobed 

 bodies, lying against the ventral surface of the ilia, 

 at the sides of the sacrum. 



The general arrangement of the veins is as follows : 



The large veins enter each kidney, the femoral 

 and the hypogastric, returning blood from the leg 

 and the intestine respectively. They traverse the 

 kidney and unite within it. The common trunk 

 formed by their union is joined by the renal vein, 

 returning blood from the substance of the kidney 

 itself, and emerges from the inner side of the kidney 

 as the iliac vein, which unites with its fellow of the 

 opposite side to form the posterior vena cava. 



a. The posterior mesenteric vein is a median vein 



running backwards in the mesentery supporting 

 the rectum : it collects the blood from the hinder 

 part of the small intestine, and from the rectum 

 and cloaca. Opposite the posterior end of the 

 kidneys it receives a small median caudal vein 

 from the tail, and at once divides into the right 

 and left hypogastric veins. 



b. The hypogastric vein of each side is joined by the 



internal iliac vein from the inner surface of the 

 pelvic cavity, and then enters the kidney at its 

 posterior end : it runs forwards through the 



