39 



The Isolation from Peat of Certain Nucleic Acid Derivatives. 



By W. B. BoTTOMLEY, M.A., Professor of Botany, University of London, 



King's College. 



(Communicated by F. Oliver, F.R.S. Received May 31, 1917.) 



In a previous communication* describing the stimulating effect of certain 

 organic substances, extracted from " bacterised " peat, on the growth of 

 Lemna minor in water-culture solution, it was suggested that some of the 

 substances may act directly as organic nutrients, being absorbed as such and 

 utilised directly for building up the protein and other complex nitrogenous 

 constituents of the plant. 



The marked effect of these substances on the development of the nucleus 

 in the cells of the Lemna. minor plants also suggested the possible presence of 

 some nuclear constituent, such as nucleic acid, in the extracts. An examina- 

 tion of the aqueous extract of " bacterised " peat showed that, although it 

 contained no nucleic acid, certain purine and pyrimidine bases, together with 

 phosphoric acid, were present. As the presence of these free radicles 

 indicated the possibility that nucleic acid exists as such in raw peat, and is 

 decomposed by further bacterial treatment, an attempt was made to isolate 

 nucleic acid from raw peat. 



The usual method of obtaining nucleic acid from soil is by precipitating an 

 alkaline extract of soil with hydrochloric acid, filtering off the precipitate, 

 and pouring the filtrate, after concentration in vacuo, into an excess of alcohol 

 containing sodium acetate. By this method, however, there is danger of 

 precipitating some of the nuoleic acid with the humic acid. 



Schreiner and Lathropf in their soil investigations used acetic acid instead 

 of hydrochloric acid to acidify the alkaline extract. This precipitates humic 

 acid, but not the nucleic acid. 



A combination of these methods was first employed in the extraction of 

 nucleic acid from raw peat. An alkaline extract was obtained in the usual 

 way by treatment with a 1-per-cent. solution of caustic soda. This was just 

 neutralised with hydrochloric acid, then acidified with acetic acid, and the 

 humic acid filtered off. The filtrate was treated by the ordinary method for 

 the separation of nucleic acid, and a flocculent precipitate obtained. This 

 substance was much darker in colour than yeast nucleic acid, and was 



* ' Roy. Soc. Proc.,' B, vol. 89, p. 481 (1917). 



t Schreiner and Lathrop, ' U.S. Dept. Agric, Bureau of Soils, Bull. 89 ' (1912). 



