NUCLEIC ACIDS. 179 



All nucleic acids contain phosphoric acid. The relation between phos- 

 phorus and nitrogen is as 1 : 4 in the inosinic acid and as 1 : 5 in the guanylic 

 acid. In the thymus- and the salmo-nucleic acids the relation accord- 

 ing to SCHMIEDEBERG is 4:14 and according to STEUDEL 4:15. In the 

 triticonucleic acid, OSBORNE and HARRIS found the relation 4:16; in the 

 yeast nucleic acid, LEVENE and JACOBS found it was equal to 4:15. 



According to the number of bases contained in the nucleic acids 

 we can differentiate between the simple nucleic acid with only one base 

 and the complex nucleic acids with several bases. LEVENE and MANDEL l 

 have called the first (inosinic acid, guanylic acid) nudeotides or mono- 

 nucleotides arid the last poly nudeotides. 



The properties and the constitution of the nucleic acids, as far as we 

 know them, have been determined essentially by the work of KOSSEL 

 and his pupils, by SCHMIEDEBERG, STEUDEL and LEVENE 2 and their 

 collaborators. 



On complete acid hydrolysis the nucleic acids are split into the three 

 above mentioned components, phosphoric acid, carbohydrate and bases. 

 The purine bases are more readily split off than the pyrimidine bases 

 and on careful acid hydrolysis of thymus nucleic acid, a new acid, the 

 thyminic acid of STEUDEL and BRIGL is obtained. This acid is very 

 similar to the thyminic acid of KOSSEL and NEUMANN 3 with the barium 

 salt, Ci6H23NsP2Oi2Ba, and the nudeotinphosphoric acid of SCHMIEDE- 

 BERG. This acid differs probably from the original nucleic acid only 

 by the absence of purine bases. By the action of strong nitric acid in 

 the cold we can, according to the method suggested by STEUDEL, ' split 

 off the purine bases while nearly all the phosphoric acid remains in organic 

 combination with the carbohydrate complexes. 



The hydrolyses of pentose containing nucleic acids as carried out by 

 LEVENE and JACOBS in neutral, or, if the pyrimidine complexes of the 

 plant nucleic acid were being studied, in ammoniacal reaction, by heating 

 to high temperatures in the autoclave or in sealed tubes, are of special 

 interest. In these cases the binding with the phosphoric acid was rup- 



1 Ber. d. d. chem. Gesellsch., 41. 



2 The work of Kossel and his pupils on the nucleic acids can be found in: Arch, 

 f. (Anat. u.) Physiol. 1892, 1893 and 1894; Sitz. Ber. d. Berl. Akad. d. Wiss., 18, 1894; 

 Centralbl. f. d. med. Wiss. 1893; Ber. d. d. chem. Gesellsch., 26 and 27; Zeitschr. f. 

 physiol. Chem., 23 and 38; see also Neumann, Arch. f. (Anat. u.) Physiol., 1898 and 1899 

 Suppl.; Miescher, Hoppe-Seyler's Med. chem. Unters., p. 441 and Arch. f. exp. Path, 

 u. Pharm., 37; Schmiedeberg, ibid., 37, 43, and 57; Altman, Arch. f. (Anat. u.) Physiol., 

 1889; Steudel, ibid., 42, 43, 46, 49, 50, 52, 53, 55, 56, 70, 77; Ascoli, Zeitschr. f. physiol. 

 Chem., 28 and 31; Levene, ibid., 32, 37, 38, 39, 43, 45; Levene and Mandel. ibid. 46, 

 47, 49, 50; Inouye and Kotake, ibid., 46; Levene and Jacobs, Ber. d. d. chem. 

 Gesellsch., 42, 43, 44; with La Forge, ibid., 43 and 45. 



3 Steudel and Brigl, Zeitschr. f. physiol. Chem., 70; Kossel and Neumann, ibid., 22. 



