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HUMAN PHYSIOLOGY 



to popular belief, the secretions of the skin have the 

 slightest share in the total work of excretion. The great 

 value of the sweat glands is not at all in connection with 

 the removal of waste but in the dissipation of heat. 



FIG. 65. The kidneys and the urinary bladder. The two kidneys 

 are shown within an outline which suggests the body cavity. Their 

 advantageous connections with the chief artery and vein of the system 

 are indicated. Below is the bladder reached by the two ureters. These 

 vessels enter the bladder low down and behind not at the level where 

 they disappear from the figure. 



The expired air carries out from the body nearly all the 

 carbon dioxid and a rather large volume of water, some- 



