x THE NUCLEIC ACIDS 445 



Many toxins are also precipitated by nucleic acids according to 

 Tichomiroff, 1 and the strong disinfecting action of free nucleic acid 

 observed by Kossel 2 depends, perhaps, also on its albumin-precipitat- 

 ing power. Introduced into the blood, thymus-nucleic acid causes 

 a marked hyperleucocytosis, while its salts are inactive, according to 

 Neumann; 3 in doses of 10 grammes it is indifferent to man. 



Goto 4 has noticed a very important property of nucleic acid, 

 namely, that of keeping purin- bases and uric acid in solution. 

 Whether uric acid is kept by this means in solution in the body is 

 as yet uncertain, but the property is of the very greatest importance 

 in physiological investigations, for it is impossible to determine 

 purin-bases and uric acid quantitatively in the presence of nucleic 

 acids. 



Nucleic acids are, as Neumann has shown, ve^ readily decom- 

 posed by boiling with acids, or even with pure water ; but they are very 

 resistant towards the action of alkalies, especially if sodium acetate 

 be added. Alkalies have, therefore, been used for isolating nucleic 

 acids. 



When nucleic acids disintegrate, they do not at once give rise 

 to the above-mentioned dissociation-products, as a number of inter- 

 mediate products are formed in the first instance. Neumann 5 and 

 Kostytschew 6 state that the nucleic acid 'a,' which can be isolated 

 from such tissues as the thymus, is converted when it is boiled for two 

 hours with alkalies into nucleic acid 'b.' This latter no longer 

 gelatinises ; with barium and calcium it does not give a gelatinous 

 precipitate; it contains only -a portion of the purin-bases originally 

 present, and for this reason less nitrogen than the a-nucleic acid. 

 When b-nucleic acid is still further hydrolysed it gives rise to the 

 thyminic acid, which contains no purin-bases, and to which Kossel and 

 Neumann 7 have given the formula C 16 H 25 N 3 P 2 12 . The thyminic acid 

 also precipitates albumin in an acid solution, and keeps purin-bases in 

 solution. As an intermediate product between b-nucleic acid and 

 the thyminic acid Neumann 5 has described the nucleo-thyminic acid. 



The dissociation of the nucleic acids into the just-mentioned 

 intermediate and into the final products does not only occur when 



1 M. Tichomiroff, Zeitschr. f. physioL Chem. 21. 90 (1895). 



2 A. Kossel, Arch. f. (Anat. u.} PhysioL, Physiol. Abtl. 1893, p. 157 ; A. and H. 

 Kossel, ibid. 1894, p. 200. 



3 A. Neumann, ibid. 1898, p. 374 (Verhandlungen der Berliner physioL Gesellscha/t). 



4 M. Goto, Zeitschr. f. physiol. Chem. 30. 473 (1900). 



5 A. Neumann, Arch. f. (Anat. u.) Physiol. 1899, Suppl. p. 552. 



6 S. Kostytschew, Zeitschr. f. physioL Chem. 39. 545 (1903). 

 * 7 A. Kossel and A. Neumann, ibid. 22. 74 (1896). 



