NUCLEIC ACIDS. 175 



Pentoses have been found as the carbohydrate group in the guanylic 

 acid, the inosinic acid, and the plant nucleic acids (yeast and triticonucleic 

 acids), and a hexose has also been found in the yeast nucleic acid. In 

 the other animal thymo-nucleic acids, a hexacarbohydrate occurs, as 

 shown by the investigations of STEUDEL. 1 We can differentiate between 

 two different groups of nucleic acids according to the kind of carbohy- 

 drate complexes they contain. 



Another difference also exists, as above shown, in the number and 

 kind of purine and pyrimidine bases in the nucleic acids. According to 

 the number of these bases we can differentiate between the simple nucleic 

 acids with only one base and complex nucleic acids with several bases. 

 LEVENE and MANDEL 2 designate the first group nucleotides or mononu- 

 cleotides and the second group poly nucleotides. As we are in the habit of 

 designating as nucleolin or nucleotinic acid (see below), only those 

 cleavage products of nucleic acids containing no purine base, but merely 

 pyrimidine bases, it is not proper, according to HAMMARSTEN, to desig- 

 nate as nucleotides such bodies as guanylic acid and inosinic acid, which 

 contain no pyrimidine, but only purine base. Until the nature of the 

 nucleic acids is completely explained, it would be better to differentiate 

 between mono- and polynucleic acids, or perhaps still better between 

 simple and complex nucleic acids. Yet we must bear in mind that the 

 complex nucleic acids have not been isolated from compound proteins, 

 but generally from organs, namely, from mixtures of several nucleo- 

 proteins; hence we cannot know whether these acids are chemical indi- 

 viduals or whether they are mixtures of closely related simple nucleic 

 acids. On the other hand, it is also possible that the simple nucleic 

 acids may be derived from more complex ones by cleavage. Such an 

 assumption does not apply to the guanylic acid, as its mother protein 

 contains only one base, namely guanine. 



We generally admit of 4 atoms of phosphorus in the empirical' formula 

 of the various nucleic acids. The relationship of phosphorus to nitro- 

 gen in the thymus- and the salmo-nucleic acid is according to SCHMIEDE- 

 BERG 4 to 14, and according to STEUDEL 4 to 15. OSBORNE and HARRIS 

 found the relationship 4 to 16 in the triticonucleic acid, and BANG 3 

 found the relationship 4 to 20 in the guanylic acid. 



All nucleic acids are amorphous, white, and have an acid reaction. 

 They are readily soluble in ammoniac al or alkaline water. They also 

 dissolve in concentrated acetic acid and form insoluble salts with copper 



1 Zeitschr. f. physiol. Chem., Bd., 50, 52, 53, 55, 56. 



2 Ber. d. d. chem. Gesellsch., 41. 



3 Schmiedeberg, Arch. f. exp. Path. u. Pharm., 3", 4'3, 57; Steudel, Zeitschr. f. 

 physiol. Chem., 49, 53, p. 14; Orborne and Harris, ibid., 36; Bang, ibid., 26 and 31, 

 and Hofmeister's Beitrage, 5 and Biochem. Centralbl., 1, p. 295. 



