PLANT NUCLEIC ACIDS. 185 



the formula C4oH56Ni4Oi6.2P205. According to STEUDEL for every 4 

 atoms of phosphorus we have 15 atoms nitrogen and from this he has 

 calculated the formula C43HeiNi5P4O34+9H2O for the acid containing 

 water. 



The probable constitution of the thymo-nucleic acids has been previ- 

 ously indicated and as positively known cleavage products we have at least 

 phosphoric acid, a hexose carbohydrate, guanine, adenine, thymine and 

 cytosine. 



The thymo-nucleic acids have the reactions as given for the complex 

 nucleic acids. They are amorphous, dextro-rotatory, and soluble in cold 

 water with difficulty. They form soluble salts with alkalies and the acid 

 is precipitated from these solutions by mineral acid but not by acetic 

 acid. Tannic acid alone does not cause a precipitate but does in the 

 presence of sodium acetate. Proteins precipitate their solutions contain- 

 ing acetic acid. The two special thymo-nucleic acids differ from each 

 other by the different behavior of their salts (see above). 



The preparation of the nucleic acids is based in the first place always 

 upon the cleavage of the nucleoprotein into protein and nucleic acid by 

 the action of alkali and then separating the nucleic acids from the 

 protein. The operations necessary for purifying the nucleic acids from 

 proteins are very complicated and we must refer to the works of 



SCHMIEDEBERG, NEUMANN, LEVENE, and Others. 1 



Plant Nucleic Acids. The two best known acids of this group are 

 the yeast nucleic acid and the triticonucleic acid isolated from the 

 wheat embryo. The identity of these two acids, as suggested by OSBORNE 

 and HARRIS has become more and more probable. According to KOWA- 

 LEWSKY 2 the yeast nucleic acid contain only adenine, guanine and cytosine, 

 the uracil is only formed secondarily from the cytosine. The yeast nucleic 

 acid may perhaps be a triphosphoric acid with three molecules of pentose 

 each with a molecule of adenine, guanine and cytosine. 



This view stands in opposition to the observations of LEVENE and 

 JACOBS 3 that the yeast nucleic acid contains one molecule of pentose 

 combined with adenine and guanine, and besides this it contains two 

 pyrimidinehexose complexes, cytidine and uridine. 



The triticonucleic acid yields also, as OSBORNE and HEYL, WHEELER 

 and JOHNSON and recently LEVENE and LA FORGE 4 have shown, the same 

 hydrolytic products as the yeast nucleic acid and both contain d-ribose. 



1 Schmiedeberg, Arch. f. exp. Path. u. Pharm., 43 and 57; Herlant, ibid., 44; Neu- 

 mann, Arch. f. (Anat. u.) Physiol. 1899 Supplb.; Levene, Zeitschr. f. physiol. Chem., 

 32 and 45; Kostytschew, 1. c. 



2 Osborne and Harris, Zeitschr. f. physiol. Chem., 36; Kowalewsky, ibid., 69. 



3 Ber. d. d. chem. Gesellsch., 44. 



4 Osborne and Heyl, Amer. Journ. of Physiol., 21; Wheeler and Johnson, Amer. 

 Chem. Journ., 29; Levene and La Forge, Ber. d. d. Chem., Gesellsch., 43. 



