ELEMENTARY CHEMICAL PHYSIOLOGY 



267 



1. Cystin. This forms a deposit somewhat like that of urates in 

 appearance. 



Microscopically, however, it shows a distinct crystalline structure 

 consisting of hexagonal colourless plates or slabs (Fig. 188). When 

 the crystals are present the condition is called cystinuria. 



2. Leucin and Tyrosin. Though very rarely, these two bodies 

 sometimes occur in urine (e.g. in severe hepatic disease), where their 

 appearance is similar to that in a pancreatic digest (see Fig. 234). 



3. Hippuric Acid. This may appear in urine during the admin- 



FIG. 190. Calcium oxalate. X 500. 



It is 



istration of benzoic acid. It crystallises in four-sided prisms, 

 quite common in the urine of herbivora. 



In Alkaline Urine the following may occur : 



1. Phosphates. Of these there are two kinds, viz., phosphate of 

 calcium and ammonium-magnesium phosphate. 



(a) Phosphate of Calcium. The sediment is chalky and never 

 pigmented ; it clears up on adding a few drops of nitric acid ; it is 

 increased by boiling. Microscopically it is usually amorphous, but 



