THE RABBIT. 



63 



inter-lobular artery and vein, and at the centre open into 

 the intra-lobular vein (fig. 24). When both this network 

 of blood-capillaries and the system of bile-capillaries have 

 been injected, it is found that the two are totally distinct, 

 and that there is always at least one liver-cell between 

 a blood -capillary and a bile -capillary. This is, of course, 

 exactly what we should expect from the structure of simpler 

 glands. 



The functions of the liver have already been partly stated. 

 It secretes bile, and regulates the amount of sugar in the blood. 

 A third function is apparently this : the waste-products of 

 katabolism, especially of muscles, cannot be directly excreted 

 by the kidneys, but in the liver they undergo change into 

 urea, and this can be removed from the blood by the kidneys. 



19. The Kidneys or renal organs are a pair of compact 

 glandular masses, from each of which a duct, the ureter, 

 leads to the 

 median 

 urinary 

 bladder, 

 where the 

 urine is stored 

 up in the in- 

 tervals be- 

 tween its 

 periodic ex- 

 pulsions from 

 the body. If 

 a median 

 section of the 

 kidney and 

 adjoining part 

 of the ureter 

 is taken (fig. 

 25), it is seen 



that where the ureter meets the kidney its cavity expands 

 into a large space called the pelvis of the kidney. Pro- 

 jecting into this space is the pyramid. The main mass of 

 the kidney is divided into an inner and outer portion, 



i-r./r "/? 



Fig. 25. DIAGRAM OF BABBIT'S KIDNEY. 



