U8 WALTER JCLXES 



If the structures of these compounds be admitted, then the constitu- 

 tion of thymus nucleic acid is indicated. 



HO\ 



0=P O . C H 10 4 . C S H 4 K 5 

 O/ 



H0\ | 



O^P^-0 . C G H 8 2 . C 5 II X 2 2 

 HO/ | 



O 

 H0\ | 



O-P . C G H 8 2 . 4 II 4 XoO 

 HO/ | 



0\ 



0-P O . C C H 10 4 . C 5 H 4 1S T 5 

 HO/ 



Reduced to its simplest terms, this complicated formula means the fol- 

 lowing* : 



1. Thymus nucleic acid, like yeast nucleic acid, is a tetra-nucleo- 

 tide composed of the groups of four mono-nucleotides. 



2. The linkages that join the four mono-nucleotide groups to one an- 

 other are differently located in the two nucleic acids. 



With the latter statement physiology is at present little concerned. 

 With the former statement physiology is very much concerned; for the 

 decomposition of the two nucleic acids under the influence of animal fer- 

 ments follows parallel lines* With reference to animal metabolism the 

 two nucleic acids have an "equivalent" structure. 2 



Physiological Part 



THE PHYSIOLOGICAL DECOMPOSITION OF NUCLEIC ACID 



The discovery of nucleic acid in the tissues naturally prompted a host 

 of investigations to find a physiological agent capable of decomposing the 

 substance. It was assumed, without justification, that such a decomposi- 

 tion would involve the simultaneous disruption of all of its linkages with 

 the simultaneous production of all of its fundamental decomposition prod- 

 ucts. Of these substances, only phosphoric acid and the purine bases can 



2 While this article was in press Levene abandoned the above formula for thymus 

 nucleic acid (J. Biol. Chern., 48, 1921, 122) and Thannhauser has added an important 

 contribution to the subject. (Thannhauser and Ottenstein. Zeits. f. physiol. Chem., 

 114. 1921. 39.) 



