50 PHYSIOLOGICAL CHEMISTRY. 



and add the xanthin to this mixture, at first a dark green and then 

 quickly a brownish halo forms around the xanthin grains and then 

 disappears (HOPPE-SEYLEE). If xanthin be warmed in a small 

 vessel on the water-bath with chlorine-water and a trace of nitric 

 acid and evaporated to dryness, when the residue is exposed under 

 a bell-jar to the vapors of ammonia a red or purple-violet color is 

 produced (WEIDEI/S reaction). It is still a question whether en- 

 tirely pure xanthin will give this reaction. 



Hypoxanthin or SAEKIN, C B H 4 N 4 0. This body is found in the 

 tissues containing xanthin. It is especially abundant in the sperm 

 of salmon and carp. It occurs also in the marrow. In normal 

 urine it appears in very small quantities, and it seems also to be 

 found in milk. It is found in rather significant quantities in the 

 blood and urine in leucocythaemia. 



Hypoxanthin forms very small colorless crystalline needles. It 

 is more soluble than xanthin. It dissolves in 300 parts cold and 

 78 parts boiling water. It is nearly insoluble in alcohol, but it is 

 dissolved by alkalies and acids. The combination with hydrochloric 

 acid crystallizes and is more soluble than the corresponding xanthin 

 combination. It acts in ammoniacal solution like xanthin with 

 silver nitrate. The silver combination of hypoxanthin dissolves 

 with difficulty in boiling nitric acid of 1.1 sp. gr., and on cooling 

 the double combination separates as crystalline needles. Treated 

 like xanthin with nitric acid, hypoxanthin gives a nearly colorless 

 residuum which does not become red by heating with alkali. Hypo- 

 xanthin does not give WEIDEI/S reaction. After the action of 

 hydrochloric acid and zinc a hypoxanthin solution becomes first 

 ruby-red and then brownish red in color on the addition of an excess 

 of alkali (KOSSEL). 



NH.CH-.C.NH 



Guamn, C 5 H 5 N 6 = NH . ^ NH c-N > Ghtanin is 



found in organs rich in cells, such as the liver, spleen, pancreas, testi- 

 cles, and in salmon-sperm. It is further found in the muscles (in very 

 small amounts), in the scales and in the air-bladder of certain fishes 

 as iridescent crystals of guanin lime; in the retina epithelium of 

 fishes, in guano, and in the excrement of spiders it is found as chief 

 constituent. Under pathological conditions it has been found in 



