THE ANIMAL CELL. 49 



p. m. xanthin bodies, against only traces in the normal blood. 

 That the xanthin bodies are also intermediate steps in the forma- 

 tion of urea or uric acid in the animal organism, as will be shown 

 later (see Chapter XIV), is probable. 



Those xanthin bodies which have thus far been obtained in the 

 decomposition of the nucleins, or generally from cells, or from 

 tissue rich in cell nuclei, and on this account will be described 

 here, are xanthin, hypoxanthin, guanin, and adenin, all of which 

 are found in the vegetable kingdom (SCHULZE and BOSSHAKD, 

 KOSSEL, BAGINSKY). The carnin, which has only been found in 

 meat extracts (WEIDEL) and in the flesh of certain fishes, as also 

 in the bodies paraxanthin and heteroxanthin (SALOMON), which 

 are only found in urine, will be described in their proper chapters, 



namely, IX and XIV. 



TVTTT PIT O ~\TTT 



Xanthin, O.H.N.O. = ' '/ >0<> (E ' Fl8CHEE )> is 



found in the muscles, liver, spleen, pancreas, kidneys, testicles, 

 carp-sperm, thymus, and brain. It occurs in the smallest amounts 

 as a physiological constituent of urine, and it has been found rarely 

 as a urinary sediment or calculus. It was first observed in such a 

 stone by MAECET. Xanthin is found in larger amounts in a few 

 varieties of guano (Jarvis guano). 



Xanthin is amorphous, or forms granular masses of crystals. 

 It is very slightly soluble in water, in 14,151-14,600 parts at 

 -f 16 C., and in 1300-1500 parts at 100 C. (ALMEN). It is 

 insoluble in alcohol or ether, but is dissolved by alkalies or acids. 

 With hydrochloric acid it gives a crystalline, difficultly-soluble 

 combination. Xanthin dissolved in ammonia gives with silver 

 nitrate an insoluble, gelatinous precipitate of xanthin silver. This 

 precipitate is dissolved by nitric acid, and by this method an easily- 

 soluble double combination is formed. A watery xanthin solution 

 is precipitated on boiling with copper acetate. At ordinary tem- 

 peratures xanthin is precipitated by mercuric chloride and by am- 

 moniacal lead acetate. 



When evaporated to dryness in a porcelain dish with nitric acid 

 xanthin gives a yellow residue, which turns, on the addition of 

 caustic soda, first red, and, after heating, purple red. If we add 

 some chloride of lime to some caustic soda in a porcelain dish 



