212 



Human Physiology. 



has been through the liver, it passes on to the heart and 

 lungs. But it also purifies the blood of the bitter, resinous 

 excretion, the bile, which, after performing a useful function in 

 the digestive processes of the small intestines and stimulating 

 the action of the larger, passes off with the faecal 



The spleen, a large gland opposite the liver on the right side 

 of the body, appears to be rather a manufacturer than purifier 

 of the blood. Large quantities of fibrin, which separates from 

 the serum of blood in the act of clotting, are found in the 

 spleen, and some physiologists hold that its action also in- 

 creases the quantity of red globules. It has no excretory duct, 

 and very little is really known about its functions. 



The kidneys are very powerful secreting and excreting 

 organs. They secrete urine from the blood a function so 

 important that if it ceases only for two or three days, death is 

 often the result. The excretion of urine is the principal means 

 of ridding the body of the waste matter of the system, mostly 



Fig. 53- 



VERTICAL SECTION OF THE 

 LEFT KIDNEY. 



Fig. 54- 

 A PORTION OF KIDNEY 



MAGNIFIED 60 DIAMETERS. 



urea, an ammoniacal compound. The waste of muscular tissue 

 and brain matter is separated from the blood by the kidneys, 



