CHEMICAL CONSTITUTION OF THE ANIIilAL BODY. 147 



3. The Starches : Glycogen, CaHwOs, convertible into dex- 

 trose. Occurs abundantly in many foetal tissues and in the 

 Uver, especially of the adult animal. 



Dextrin, CeHioOs, convertible itto dextrose. Soluble in 

 water ; intermediate between starch and dextrose ; a product 

 of digestion. 



Pathological : G-rape-sugar occurs in the urine in diabetes 

 mellitus. 



Certain substances formed within the body may be regarded 

 as chiefly waste-products, the result of metabolism or tissue- 

 changes. 



They are divisible into nitrogenous metabolites and non- 

 nitrogenous metabolites. 



Nitrogenous Metabolites. 



1. Urea, uric acid and compounds, kreatinin, xanthin, hypo- 

 xanthin (sarkin), hippuric acid, all occuring in urine. 



2. Leucin, tyrosin, taurocholic, and glycocholic acids, which 

 occur in the digestive tract. 



3. Kreatin, constantly found in muscle, and a few others of 

 less constant occurrence. 



The above consists of C, H, N, O. Taurocholic acid contains 

 also S. 



The molecule in most instances is complex. 



Non-Nitrogenous Metabolites. 



These occur in small quantity, and some of them are secreted 

 in an altered form. 



They included lactic and sarcolactic acid, oxalic acid, succinic 

 acid, etc. 



