422 CHEMISTRY OF THE LEUCOMAINS. 



A Base, C^H^Np, was obtained by Gautier from fresh muscle 

 tissue of beef, according to the method given on page" 455, and on 

 account of a resemblance in some of its properties with xanthin he 

 named it pseudozanthin. This name is very inappropriate, not 

 only because it differs so much in ita empirical formula from that of 

 xanthin, C^H^N^j , but also because the term pseudoxanthin has 

 already been applied by Schultzen and Filehne to a body isomeric 

 with xanthin, which was obtained by the action of sulphuric acid 

 on uric acid. 



The free base forms a light yellow powder, slightly soluble in cold 

 water, soluble in weak alkali and in hydrochloric acid. The hydro- 

 chlorid is very soluble, and it forms stellate prisms with curved 

 faces, which resemble the corresponding salt of hypoxanthin, and to 

 some extent, also, the whetstone-shaped crystals of uric acid. 



Like xanthin, its aqueous solution is precipitated in the cold by 

 mercuric chlorid, silver nitrate, and by ammoniacal lead acetate, but 

 not by normal lead acetate. On evaporation with nitric acid, the 

 residue gives, on contact with potassium hydrate, as in the case of 

 xanthin, a beautiful orange-red coloration (xanthin reaction). It 

 differs from xanthin, not only in its empirical composition, but also 

 in its greater solubility and in its crystalline form. It is possible 

 that this base, on account of its great resemblance to xanthin, may 

 have been mistaken, at different times, for that compound. It is to 

 be noted, however, that this base has not been met since Grautier's 

 work. If the formula given is correct, the base may be considered 

 as a pyrimidin body, such as a di-imido derivative of the preceding. 



HEXON BASES. 



The purin bases through the studies of Kossel have been shown 

 to be derivatives of the nuclein which exist within the nuclei of cells. 

 They are therefore to be looked upon as essentially products of nuclear 

 metabolism and more especially of the nuoleinic acids. If the results 

 obtained by Bang with guanylic acid, a nucleinic acid from the pancreas, 

 be correct and hold true for the other nucleinic acids then all the nitro- 

 gen contained in these acids is in the purin form and hence would leave 

 the body to some extent as purin bases, but chiefly in the oxidized 

 form as uric acid. A portion of the purin bodies, however, may 

 undergo hydrolytic change and appear in the urine as pyrimidin 

 derivatives or even in the more simple form of allantoin, creatinin and 

 urea. The presence of allantoin and oxalic acid in urine and even 

 in sprouts is thus accounted for. 



On the other hand extensive investigations carried on during the 

 past ten years have shown the existence of a group of basic sub- 

 stances characteristic of proteid bodies and in no wise related to the 

 nucleinic acids and their products. These basic substances have 



