682 URINE. 



consequently the excretion of allantoin is considerably increased, 

 according to MINKOWSKI, COHN, SALKOWSKI, and MENDEL and BROWN, 1 

 after feeding thymus or pancreas. A strong allantoin excretion is also 

 found in dogs after poisoning with hydrazine (BoRissow), hydroxylamine, 

 semicarbazide, and aminoguanidine (POHL), and this increase in the 

 excretion of allantoin is connected with the nuclein metabolism. POHL 2 

 has found in dogs on poisoning with hydrazine that the liver contained 

 allantoin and that other organs contained traces, while it does not exist 

 in the organs of normal dogs, and he has also detected the formation of 

 allantoin in the autolysis of the intestinal mucosa, liver, thymus, spleen 

 and pancreas. It is very probable that in these cases we are dealing 

 with a destruction of cells and an enzymoytic uric acid formation with a 

 subsequent uricolysis with the formation of allantoin. According to 

 PODUSCHKA and MiNxowsKi, 3 allantoin introduced into dogs appears 

 almost entirely in the urine, while in man only a small portion of the 

 ingested substance is eliminated in the urine and seems in the last case 

 to be chiefly burnt. 



Allantoin is a colorless substance often crystallizing in prisms, dif- 

 ficultly soluble in cold water, easily soluble in boiling water, and also in 

 warm alcohol, but not soluble in cold alcohol or ether. A watery allan- 

 toin solution gives no precipitate with silver nitrate alone, but by the 

 careful addition of ammonia a white flocculent precipitate is formed, 

 C4H 5 AgN 4 O 3 , which is soluble in an excess of ammonia and which con- 

 sists after a certain time of very small, transparent microscopic globules. 

 The dry precipitate contains 40.75 per cent silver. A watery allantoin 

 solution is precipitated by mercuric nitrate. On continued boiling 

 allantoin reduces FEHLING'S solution. It gives SCHIFF'S furfurol reac- 

 tion less rapidly and less intensely than urea. Allantoin does not give 

 the murexide test. 



Allantoin is most easily prepared by the oxidation of uric acid with 

 lead peroxide. In preparing allantoin from urine, proceed according 

 to LOEWI'S method, which consists of the following: The faintly acidified 

 urine is precipitated with a mere urous-nit rate solution, the filtrate treated 

 with H^S, and the new filtrate precipitated by magnesium oxide and 

 silver nitrate after the removal of the H 2 S. The precipitate is filtered 

 off and washed with warm water and decomposed with H^S, and the 



1 Minkowski, Arch. f. exp. Path. u. Pharm., 41, and Centralbl. f. innere Med., 1898; 

 Cohn, Zeitschr. f. physiol. Chem., 25; Salkowski, Centralbl. f. d. med. Wissensch., 

 1898; Mendel and Brown, Amer. Journ. of Physiol., 3. 



2 Borissow, Zeitschr. f. physiol. Chem., 19; Pohl, Arch. f. exp. Path. u. Pharm., 

 46; Poduschka, ibid., 44. According to Underbill and Kleiner, Journ. of biol. Chem., 

 4^ hydrazine has no other action on the excretion of allantoin than that caused by 

 the refusal to take food brought about by the poison. 



3 Poduschka, Arch, f . exp. Path. u. Pharm., 44; Minkowski, ibid., 41. 



