74 PROTEIN POISONS 



investigated according to the method given by Kruger and 

 Solomon; 1 as no satisfactory separation was thereby ob- 

 tained, the last three precipitates were separated according 

 to the method of Ivossel and his pupils, as outlined by 

 Hammersten, 2 for the separation of the four bases, xanthin, 

 hypoxanthin, guanin, and adenin. The precipitate was 

 dissolved as completely as possible in boiling nitric acid 

 (specific gravity, 1.1), a little urea having been added 

 to prevent nitrification, filtered hot, concentrated some- 

 what, and allowed to cool. On cooling, only a slight 

 residue of 'the guanin-hypoxanthin-adenin portion separ- 

 ated out. On decomposing this precipitate, treating with 

 ammonia and evaporating, the amount obtained was so 

 small that it was not possible to make separation of the 

 bases, but ammoniacal solution produced a comparatively 

 heavy flocculent organic precipitate. The nitric acid filtrate 

 containing the xanthin portion w r as precipitated with 

 ammonia. A heavy, reddish-brown, mucilaginous precipi- 

 tate came down, but was not sufficient in quantity or 

 sufficiently free from impurities to justify an ultimate 

 analysis." 



Leach 3 obtained from 1 per cent, sulphuric acid extracts 

 of the colon cellular substance a body containing 7.33 per 

 cent, of phosphorus. It gave none of the protein color 

 reactions except the ubiquitous xanthoproteic. It could 

 hardly be anything else than a nucleic acid. However, the 

 percentage of nitrogen was only 8.98, and no known nucleic 

 acid contains so small an amount of nitrogen. In the same 

 extracts she obtained indications of the presence of two 

 xanthin bases, xanthin and guanin. The evidence of the 

 existence of nuclein bodies in the haptophor of the colon 

 cellular substance will be given later. 



Diamino-acids. Wheeler failed to obtain any evidence 

 of the presence of arginin or histidin in sarcina lutea, but 

 in each of five attempts she secured quite convincing proof 



1 Zeitsch. f. Physiol. Chem., 1898, xxvi, 373. 



2 Physiol. Chem., p. 120, as translated by Mendel. 



3 Jour. Biol. Chem., 1906, i, 463. 



