THE NUCLEINIC ACIDS. 95 



Kossel has expressed the opinion that in reality only four true 

 nucleinic acids exist, in each of which only one nucleinic base is 

 represented. He accordingly distinguishes an adenylic acid, a 



fuanylic acid, a sarcylic (hypoxanthylic) acid, and a xanthylic acid, 

 n accordance with this supposition, the spermatonucleinic acid of 

 the ox would contain three primary acids, as on decomposition it 

 yields xanthin, hypoxanthin, and adenin. Triticonucleinic acid 

 would similarly represent a mixture of guanylic acid and adenylic 

 acid ; thymonucleinic acid likewise contains both guanin and adenin, 

 etc. As a matter of fact, however, only one nucleinic acid has as 

 yet been isolated in pure form, which actually contains but one 

 nucleinic base ; the rest are hypothetical. The one acid is Bang's 

 guanylic acid, which was obtained from the pancreas. KossePs 

 adenylic acid, which was first regarded as an analogous product, was 

 shown to yield both guanin and adenin. 



As a class the nucleinic acids are but little soluble in cold water, 

 more readily so in hot water, and easily soluble in solutions of the 

 alkalies. They have not yet been obtained in crystalline form. 

 They are dibasic acids, and form both acid and neutral salts with the 

 alkalies and the heavy metals. They are precipitated by the mineral 

 acids, but not by acetic acid, with the exception of guanylic acid. They 

 are very readily decomposed on boiling with mineral acids and 

 even with water, while they are quite resistent to alkalies. Alcohol, 

 especially acid alcohol, causes their precipitation ; ammonium sul- 

 phate in the presence of acetic acid is equally effective. Tannic acid, 

 picric acid, and phosphotungstic acid may also be employed. 



All nucleinic acids give the reaction of Adamkiewicz, the xantho- 

 proteic reaction, and a marked reaction with phloroglucin and hydro- 

 chloric acid (see Pentoses). 



In acid solutions they form precipitates with albumins which, 

 according to Kossel and Milroy, closely resemble the native 

 nucleins. In the spermatozoa of fish nucleinic acids are present as 

 neutral or acid salts of protamins or histons. Owing to the readiness 

 with which the nucleinic acids combine with albumins, it has been 

 questioned whether nucleoproteids are not formed artificially during 

 their preparation from the tissues. One of the strongest arguments 

 in favor of their pre-existence is the fact that they can be salted 

 out with ammonium sulphate, but it must be admitted that there 

 is really no definite proof to show that they exist as such in the 

 cell. 



The elementary composition of the common forms is given below : 



Guanylic acid C 44 H 66 N 20 P 4 O 34 (Bang) 



Triticonucleinic acid - . . C 41 H 61 N 16 P 4 O 31 (Osborne and Harris) 

 Yeast nucleinic acid . . 

 Salmonucleinic acid. . . 

 Thymonucleinic acid . . 

 Inosinic acid 



(Miescher) 

 (Schmiedeberg) 

 9 P 3 20 (Kossel) 

 CRN P 3 2 8 Liebig and Haiser) 



