DESTRUCTION OF URIC ACID. 671 



enzyme of the ox-kidney and dog-liver and find that it is an oxidase 

 only active in faintly alkaline or neutral reaction. WIECHOWSKI has 

 also found that this enzyme transforms the uric acid into allantoin 

 almost entirely. ASCOLI and IZAR 1 have also made the remarkable 

 observation that if an extract of liver which has completely destroyed 

 a known quantity of uric acid (air or oxygen being passed through) is 

 allowed to stand for some time in the thermostat, with the exclusion 

 of air, the destroyed uric acid is gradually reformed again. It has not 

 been determined from what transformation products this is produced. 

 Stil] it is very suggestive in connection with WIECHOWSKI'S reports on 

 the formation of allantoin that the allantoin is inactive in this regenera- 

 tion of the uric acid. Further enlightenment on this point would be 

 of the greatest interest. 



From this power of the various organs of destroying uric acid it 

 follows that the quantity of uric acid eliminated is not a sure indication 

 of the amount of the acid formed. We must, therefore, admit that a 

 part of the uric acid formed in the body is destroyed in a manner similar 

 to that introduced from without. Bum AN and ScnuR 2 have indeed 

 suggested a tactor, the so-called " integral factor," with which the quan- 

 tity of uric acid eliminated in the twenty-four hours must be multiplied 

 in order to find the quantity of uric acid formed during this time. Accord- 

 ing to them, carnivora eliminate unchanged about -gV - 3^ of the uric 

 acid introduced into the circulation, rabbits about , and man \. Such 

 calculations are necessarily very uncertain, and for man, in whom accord- 

 ing to WIECHOWSKI practically no intermediary destruction of uric acid 

 occurs, they are for the present not admissible. 



Properties and Reactions of Uric Acid. Pure uric acid is a white, 

 odorless, and tasteless powder consisting of very small rhombic prisms 

 or plates. Impure uric acid is easily obtained as somewhat larger, 

 colored crystals. 



In rapid crystallization, small, thin, four-sided, apparently colorless, 

 rhombic prisms are formed, which can be seen only by the aid of the 

 microscope, and these sometimes appear as spools because of the round- 

 ing of their obtuse angles. The plates are sometimes six-sided, irregularly 

 developed; in other cases they are rectangular with partly straight and 

 partly jagged sides; and in other cases they show still more irregular 

 forms, the so-called dumb-bells, etc. In slow crystallization, as when 

 the urine deposits a sediment or when treated with acid, large, invariably 

 colored crystals separate. Examined with the microscope these crystals 

 always appear yellow or yellowish brown in color. The most common 

 type is the whetstone shape, formed by the rounding off of the obtuse 



1 Zeitschr. f. physiol. Chem., 58. 2 Pfluger's Arch., 87. 



