1174 



PHYSIOLOGY 



tisic acid in a quantity of 3 to 6 grm. per day. The amount of the acid excreted varies 

 with the protein food taken. It seems that in these cases the power of the organism to 

 break up tyrosine and phenylalanine is entirely absent. If either of these substances be 

 administered by the mouth, it is converted almost quantitatively into homogentisic acid, 

 which appears in the urine. Individuals with alcaptonuria continue to secrete homo- 

 gentisic acid during starvation, so that the tyrosine and phenylalanine set free in the 

 course of tissue disintegration undergo the same fate as when they are derived from the 

 food. Alcaptonurics apparently suffer no ill effects as a result of their abnormal 

 metabolism. The tyrosine and phenylalanine can be absorbed and play their part 



in building up the proteins of the tissues, 

 but the process or ferment is wanting which 

 is responsible for the further break-up 

 of the first product of their oxidation, 

 namely, homogentisic acid. 



URINARY DEPOSITS 



In addition to formed elements, 

 such as blood corpuscles, bacteria, or 

 pus cells, which may occur in abnor- 

 mal urine, the following deposits may 

 be found : 



(a) In Acid Urine. (1) Amorphous urates occur generally as a brick- 

 red amorphous deposit thrown down as the urine cools. It is redissolved 

 on warming the urine, and consists generally of the quadri-urates. The 



FIG. 536. Various forms of uric acid 

 crystals. (FREY.) 



i-^V->I ?-JLiT-. * N 



FIG. 537. Urinary deposit, containing uric 

 acid, sodium urate, and calcium oxalate. 



FIG. 538. Deposit of * triple ' phosphate 

 and ammonium urate. (FuNKE.) 



acid urate of sodium and of ammonium may occasionally occur in star- 

 shaped clusters of needles or as spherules with small crystals adhering to 

 them. 



(2) Uric acid. Whetstone, dumb-bell, or sheaf -like aggregations of 

 crystals, generally deeply pigmented so as to resemble cayenne pepper 

 (Fig. 536). 



(3) Calcium oxalate (Fig. 537). Colourless, transparent, highly refrac- 



