256 THE VISCERA. 



which lies near the medial border and the opening of which is 

 the hilus. It contains the pelvis (d] (the expanded beginning 

 of the duct of the kidney), and also renal vessels (e and/") with 

 their branches. These structures are enclosed in fat, which fills 

 the remainder of the sinus. Upon opening the pelvis the 

 kidney substance is seen to project into it in the form of a cone, 

 the papilla (c), the apex of which is directed mediad. On the 

 apex of the papilla are the numerous openings of the uriniferous 

 collecting-tubes, some of them opening at the bottom of an 

 apical depression of the papilla. 



In a section made parallel to the ventral surface and in the 

 median plane, the substance of the kidney is seen to consist of 

 a peripheral darker and more granular cortical portion (Fig. 

 109, b\ and of a central, lighter, less granular medullary 

 portion (ai). Both portions are marked by lines which con- 

 verge to the apex of the papilla (c}. 



THE URETER (Fig. 108, c\ Figs, in and 112, b}. The 

 duct of the kidney begins as the pelvis (Fig. 109, ^/), a coni- 

 cal sac the base of which encloses the base of the papilla. 

 From the apex of the papilla the urine passes into the pelvis. 

 The outer wall of the pelvis is continuous with the capsule of 

 the kidney. At the hilus the pelvis narrows to form the ureter 

 (Fig. 109, g}. The ureter passes caudad in a fold of peri- 

 toneum which contains fat. Near its caudal end it passes 

 dorsad of the vas deferens (Fig. ill, c), turns ventrocraniad, 

 and pierces the dorsal wall of the bladder (Fig. in, a) 

 obliquely near the neck. On the inside of the bladder the 

 openings of the ureters appear as pores about five millimeters 

 apart, and each is surrounded by a white, ring-like elevation 

 of the surface. 



THE BLADDER. VESICA URINARIA. The bladder (Fig. 

 in, a) is pear-shaped. It lies in the abdominal cavity between 

 its ventral wall and the rectum and a short distance craniad of 

 the pubic symphysis. Caudad it is continued into a rather 

 long, narrow neck (/") which passes dorsad of the symphysis 

 to the pelvic cavity. 



The bladder is covered by peritoneum and is held in place 

 by its neck and by three folds of the peritoneum. One of these 



