REMOVAL OF THE END-PRODUCTS OF METABOLISM 167 



sources for details. The most commonly occurring 

 compounds of an abnormal character are sugar and albu- 

 min. The significance of the sugar should be clear in the 

 light of what has been said. Its transient appearance as 

 a result of free consumption does not indicate a diseased 

 condition, but only dietetic indiscretion. Continuous elim- 

 ination shows that the body has not the usual power to 

 oxidize its sugar. The kidneys are not generally at fault; 

 the defect is in the metabolism of the pancreas or elsewhere. 

 An abundant escape of albumin (presumably drawing 

 upon the protein mass of the blood) is commonly due to a 

 disordered condition of the kidneys. It takes place, for 

 example, in Bright's disease. 



Urine when freshly secreted is ordinarily acid to litmus. 

 It may be alkaline when much vegetable food is eaten, and 

 becomes so on standing in any case. The change is due 

 to a bacterial fermentation whereby urea is transformed 

 into ammonium carbonate. An ammoniacal odor develops 

 in connection with this alteration and the liquid is likely 

 to become turbid. The deposition of a sediment under 

 such conditions is no cause for anxiety. It has often been 

 represented by unscrupulous quacks to be a serious symp- 

 tom. The urine of the herbivora, which is normally al- 

 kaline, becomes acid when the animals are fasting, and it 

 may be pointed out that they are then carnivorous living 

 upon their own flesh and fat. 



How much urine is secreted depends largely on the quan- 

 tity of water taken, so far at least as this is in excess of the 

 perspiration. Kidney activity is stimulated by almost 

 any dissolved substance foreign to the standard composi- 

 tion of the blood. The nitrates, for example, are absorbed 

 rather freely from the intestine and afterward removed by 

 the kidneys in a large volume of water. They, therefore, 

 belong to the class of bodies known as diuretics. The 

 active principle of coffee and tea has the same action. In 

 securing their own elimination such compounds may 

 promote the excretion of others. Diuretics bring about 

 their effect partly through modifying the circulation, and 



