THE URINE. 353 



tion of uric acid, also in man, has been sought by many investigators 

 (RAKKE, KUHNE), and in support of this view they claim that the 

 elimination of uric acid is increased in diseases in which the spleen 

 is enlarged, also that the elimination of uric acid by the urine is 

 decreased when the volume of the spleen is diminished by the 

 administration of large quantities of quinine. That uric acid is 

 formed in the spleen receives additional proof from the investiga- 

 tions of HORBACZEWSKI. He found a considerable new formation 

 of uric acid vjhen he allowed the pulp of the spleen and blood of 

 calves to act upon each other at the ordinary temperature, at the 

 same time passing a stream of air through the mass. He also 

 obtained extracts from the pulp of the spleen with boiling water, 

 which yielded uric acid after the action of the blood. This produc- 

 tion must depend chiefly upon decomposition products of nuclein 

 (xanthin bodies). HORBACZEWSKI claims that probably the 

 lymphatic elements are here concerned, a statement which coincides 

 with the increased elimination of uric acid in lineal leucaemia, also 

 with the parallelism existing between the digestion-leucocytes and 

 the increased elimination of uric acid occurring after taking food. 

 We have no positive basis for the statement that uric acid is formed 

 in the liver of man and mammalia, but the formation of uric acid 

 in the liver of birds is shown to be highly probable by the researches 

 of MINKOWSKI. 



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

 odorless, and tasteless powder consisting of very small rhombical 

 prisms or plates. Impure uric acid is easily obtained as somewhat 

 larger, colored crystals. 



In quick crystallization, small, apparently colorless, thin, four- 

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

 microscope, are formed, and these sometimes appear as spools 

 because of the rounding 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, always colored crystals 

 separate. Examined with the microscope these crystals appear 

 always yellow or yellowish .brown in color. The most ordinary 



