EXCRETION 289 



It will be observed from a study of the excretory 

 functions of the intestine that they are so entirely 

 different from those of the kidney that it is unlikely 

 that the bowel can be made to replace the kidney to 

 any extent as a channel of excretion in cases of renal 

 disease. 



The excretory functions of the lung's have been con- 

 sidered in another chapter (Chap. VI.), and, as regards 

 the skin, it need only be said that the sweat is essentially 

 a secretion which is of use in regulating the body 

 temperature, and is not properly an excretion at all. 

 Incidentally it may contain any soluble substance which 

 is present in excess in the blood such, for example, as 

 urea ; but, like the intestine, it can never be made to 

 take the place of the kidney to any appreciable degree, 

 and the value of maintaining a free action of the skin in 

 cases of renal disease is probably to be ascribed to effects 

 other than the promotion of excretion. 



19 



