BOOK IV. 



URINARY APPARATUS. 



THIS apparatus, though simple, yet plays a very important part in the 

 animal economy, as it is charged with the duty of eliminating from the blood, 

 along with the superfluous water and other accessory substances, the excre- 

 mentitial azotised products resulting from the exercise of the vital functions. 

 These products we find in the urine the liquid secreted by the kidneys, and 

 which is carried by the ureters into a special reservoir, the bladder, where it 

 accumulates, and whence it is expelled from the body by the urethral canal, at 

 periods more or less distant, according to the requirements of the animal. 



The kidneys, the essential organs of urinary depuration, will be first 

 studied ; then the excretory apparatus ; and, finally, a brief notice will be 

 given of the suprarenal capsules small appendicular bodies annexed to the 

 kidneys, and whose function is not yet determined. 



Preparation. Place the animal in the first position, and remove one of the posterior 

 limbs. Take out the intestines, adopting the precautions indicated at page 385. Saw 

 through the pelvic symphysis, as well as the neck of the ilium on the side opposite the 

 remaining abdominal member, removing the coxal portion between these sections. The 

 pelvic cavity being now opened, the urinary apparatus is exposed, and to complete the pre- 

 paration it is necessary to : 1, Remove the peritoneum, to show that the urinary appara- 

 tus is situated external to that membrane; 2, Free the ureters an 1 kidneys from the 

 cellulo-adipose tissue surrounding them, but retaining the vessels of the latter, and 

 leaving undisturbed their relations with the pancreas and suprarenal cnpsules; 3, Inflate 

 the bladder, anot dissect its neck, taking care to preserve the orbicular peritoneal fold 

 which envelops its anterior cul-de-sac. 



In the male, the inflation of the bladder is very simple, and requires no directions. 

 In the female, however, it is requisite first to close the meatus urinarius, which is ac- 

 complished by drawing its two lips towards the entrance to the vulva, by means of two 

 chain-hooks, passing two pins through their mucjus membrane, and tying a li^atuie 

 behind th< se ; the bladder is then inflated by the ureter. 



Independently of this dissection in situ, it is advisable to examine the urinary 

 apparatus when isolated, and laid arranged upon a table, as in Fig. 247. We can then 

 study : 1, By dissection, the structure of the kidneys and arrangement of the pelvis 

 reualis ; 2, The mode of termination of the ureters ; 3, The interior of the bladder. 



1. The Kidneys. (Figs. 182, 247.) 



Situation. These are two glandular organs situated in the abdominal 

 cavity, to the right and left of the sublumbar region, lying against the 

 great psoas muscles, and maintained in that position : 1, By an envelope 

 of cellulo-adipose tissue ; 2, By the peritoneum, which passes beneath them : 

 3, By the pressure of the digestive organs contained in the abdominal cavity. 



Their situation is not absolutely alike, for the right comes forward to 

 beneath the two last ribs, while the left scarcely reaches beyond the eighteenth 

 rib. The latter is therefore more posterior than the former. 



External conformation. Studied externally, the kidneys present a special 

 form, which often serves as a term of comparison, and resembles'*more or less 

 that of a haricot bean, or the heart on a playing card. The latter con- 

 figuration is most frequently noticed in the right kidney, the left being 

 generally like the first. 



