PHOSPHOROUS SUBSTANCES OF THE CELL. 139 



■crystalline substance which has been named thymin. On 

 boiling the nucleic acid with 30 per cent, sulphuric acid or 

 heating it under pressure in water to 170° C. Kossel and 

 Neumann l were able to isolate this substance from the 

 resulting solution. It is only slightly soluble in cold but 

 easily soluble in hot water. It is also dissolved by hot 

 alcohol. It has a bitter taste, and on careful heating it 

 sublimes. It possesses neither acid nor basic properties, is 

 not precipitated by phospho-tungstic acid, but is by mer- 

 curic chloride, or an ammoniacal solution of silver oxide. 

 Its formula is C 5 H 6 N 2 2 , and it is therefore isomeric with 

 methyl-uracil. They also prepared it from the nucleic acids 

 obtained from yeast and from the spleen. In working upon 

 the nucleic acid obtained from salmon spermatozoa 

 Miescher- also obtained a non-basic body of the formula 

 C 5 H 6 N 2 2 , to which Schmiedeberg gives the name 

 nucleosin. This body has also been prepared from the 

 same source by Kossel, 3 who has shown that it is identical 

 with the thymin previously described by him. 



Another body which has been obtained as the result of 

 partial decomposition of the nucleic acid of yeast is a phos- 

 phorus-containing acid which Kossel 4 terms plasmic acid. 

 This was obtained as the result of the action of dilute 

 alkalies on nuclein at ordinary temperatures. The proteid 

 part of the molecule is gradually split off from the nuclein, 

 and bodies richer in phosphorus are thus obtained, of which 

 the most complex is plasmic acid. It differs from nucleic 

 acid by its solubilities, being readily dissolved by water or 

 dilute hydrochloric acid and can thus be easily separated 

 from nucleic acid. Like nucleic acid, it precipitates proteids 

 In acid solution, and thus closely resembles thyminic acid, 

 from which, however, it differs, in that nuclein bases are 

 found among its decomposition products after it has been 



1 Kossel u. Neumann : Ber. d. d. chem. Gesell., Bd. 26, S. 2753, 

 1893; ar >d Bd. 27, S. 2215, 1894. See also Arch. f. (Anal, u.) Physiol., 

 1894, PP- 194- 536 and 551. 



2 Miescher: Arch.f. exp. Path. u. Pharm., Bd. 37, S. 125, 1896. 



3 Kossel : Zeitschr. f. physiol. Chem., Bd. 22, S. 188, 1896. 



4 Kossel : Arch.f. (Anal, u.) Physiol., 1893, p. 157. 



