NITROGENOUS METABOLISM 159 



large surplus of uncombined amino-acids is usual ; these are 

 dealt with by the liver, and the best-known resulting pro- 

 ducts are urea destined to be excreted and glucose, 

 for which all the possibilities exist that have been men- 

 tioned above. The amount of wasting suffered by nitrog- 

 enous tissues as a part of their life process is believed to 

 to be indicated by the extent to which the product creatinin 

 is eliminated. All proteins yield sulphur compounds 

 among their decomposition products. Some yield phos- 

 phorus compounds also, and it is these proteins which 

 give rise to much of the uric acid which often tends to 

 be retained and to cause trouble. 



