464 PHYSIOLOGICAL CHEMISTRY 



obtained as a decomposition product of protein see Fig. 28, page 80. 

 Tyrosine crystallizes in urdinary sediments in the well-known sheaf 

 or tuft formation (Fig. 25, page 76). For other tests on leucine and 

 tyrosine see pages 86 and 87. 



Hematoidin and Bilirubin, There are divergent opinions regard- 

 ing the occurrence of these bodies in urinary sediment. Each of them 

 crystallizes in the form of tufts of small needles or in the form of small 

 plates which are ordinarily yellowish-red in color (Fig. 56, page 205). 

 Because the of fact that the crystalline form of the two substances is 

 identical many investigators claim them to be one and the same body. 

 Other investigators claim, that while the crystalline form is the same 

 in each case, there are certain chemical differences which may be brought 

 out very strikingly by properly testing. For instance, it has been 

 claimed that hematoidin may be differentiated from bilirubin through 

 the fact that it gives a momentary color reaction (blue) when nitric acid 

 is brought into contact with it, and, further, that it is not dissolved on 

 treatment with ether or potassium hydroxide. Pathologically, typical 

 crystals of hematoidin or bilirubin have been found in the urinary 

 sediment in jaundice, acute yellow atrophy of the liver, carcinoma of 

 the liver, cirrhosis of the liver, and in phosphorus poisoning, typhoid 

 tever, and scarlatina. 



Magnesium Phosphate. Magnesium phosphate crystals occur 

 rather infrequently in the sediment of urine which is neutral, alkaline, 

 or feebly acid in reaction. It ordinarily crystallizes in elongated, 

 highly refractive, rhombic plates which are soluble in acetic acid. 



Indigo. Indigo crystals are frequently found in urine which has 

 undergone alkaline fermentation. They result from the breaking 

 down of indoxyl-sulphates or indoxyl-glycuronates. Ordinarily indigo 

 deposits as dark blue stellate needles or occurs as amorphous particles 

 or broken fragments. These crystalline or amorphous forms may occur 

 in the sediment or may form a blue film on the surface of the urine. 

 Indigo crystals generally occur in urine which is alkaline in reaction, 

 but they have been detected in acid urine. 



Xanthine. Xanthine is a constituent of normal urine but is found 

 in the sediment in crystalline form very infrequently, and then only in 

 pathological urine. When present in the sediment xanthine generally 

 occurs in the form of whetstone-shaped crystals somewhat similar in 

 form to the whetstone variety of uric acid crystal. They may be dif- 

 ferentiated from uric acid by the great ease with which they may be 

 brought into solution in dilute ammonia and on applying heat. Xan- 

 thine may also form urinary calculi. The clinical significance of 

 xanthine in urinarv sediment is not well understood. 



