178 THE PROTEIN SUBSTANCES. 



On more energetic cleavage, ALSBERG was able to isolate a phosphorus- 

 free product, nucleotin, CaoH^N^is, which contained no purine bases 

 and which, according to SCHMIEDEBERG, is the ground substance of the 

 nucleic acid. On the other hand, as shown by STEUDEL, products may 

 be obtained by the action of nitric acid which contain nearly all of the 

 phosphoric acid in organic combination with the carbohydrate complexes. 

 Such a cleavage product containing phosphoric acid and carbohydrate 

 is of special interest, as it also contained thymine, has been obtained by 

 LEVENE and MANDEL on the acid cleavage of thymus nucleic acid, and 

 called glycophosphothymic acid. The relation of this substance to the 

 thymic acid has not been investigated. 



KUTSCHER and SEEMANN obtained guanidine and urea, but no uric acid, as 

 products on the oxidation of nucleic acid with potassium permanganate. KUT- 

 SCHER and SCHENCK 1 besides these also obtained adenine, oxalic acid, acetic acid, 

 an acid having an unknown formula, and another acid which they call martamic 

 acid, besides guanidine and urea. Martamic acid has the formula C 5 H 8 N 6 O 5 or 

 C 4 H 10 N 6 O 5 and gives a silver salt which is soluble in ammonia or nitric acid, and 

 which crystallizes in tufts of leaves. The crystalline acid, which is soluble in 

 ether, sublimes at 150, and does not give the murexide test or Weidel's test. 



Nothing decisive is known as to the constitution of the thymonucleic 

 acids. According to SCHMIEDEBERG they are combinations of phos- 

 phoric acid with the above-mentioned nucleotin, a nucleotin-phosphoric 

 acid, with which the purine bases are combined in some way or another. 



STEUDEL on the contrary considers them as a tetrametaphosphoric 

 acid, each phosphorus atom having a carbohydrate group (a hexa car- 

 bohydrate) and also one of the four nitrogenous cleavage products 

 guanine, adenine, cytosine and thymine attached . This view is undoubt- 

 edly very promising, and if the statement of LEVENE and MANDEL on the 

 formation of a glycophosphothymic acid as a cleavage product of the 

 thymus nucleic acid is substantiated by further research, then this view 

 of STEUDEL will receive further support. LEVENE and MANDEL admit 

 the existence of other such mononucleotides, namely, of glycophos- 

 pho-adeninic, -cytosinic, and -guaninic acids, which are combined with 

 each other, forming a complex nucleic acid, a polynucleotide. This view 

 is very similar to that held by STEUDEL. The question whether the com- 

 plex, sometimes called true nucleic acids, are chemical individuals or 

 are only mixtures of related, simpler nucleic acids has become of interest 

 by these investigations of LEVENE and STEUDEL. 



Guanylic Acid. This acid, which was first prepared by BANG from 

 the pancreas, has, according to him, the composition C 44 H 6 6N2oP4O34- 

 It has also been found by JONES and ROWNTREE in the spleen and by 



1 Kutscher and Schenck, Zeitschr. f. physiol. Chem., 44; Kutscher and Seemann, 

 Ber. d. d. chem. Gesellsch., 36, and Centralbl. f. Physiol., 17. 



