Chemical Constituents of the Animal Body. 251 



side. According to Levene and Jacobs the nucleic acid 

 from thymus gland is a tetranucleotide produced by the 

 condensation of four nucleotides, each of which is a complex 

 of a sugar group, phosphoric acid, and a nitrogenous sub- 

 stance (either an alloxuric or pyrimidine base). The follow- 

 ing seemingly complex formula has been assigned to it : 



HO 



\ 

 = PO C 6 H 10 4 C 5 H 4 N 5 (guanine group) 



HO 



I 4 



= PO - C 6 H 8 2 C 6 H 5 N 2 3 (thymine group). 



HO 







HO 



\ 

 = PO - C 6 H 8 2 C 4 H 4 N 3 (cy tosine group) 



HO 







= PO- C 6 H 10 4 C 6 H 4 N 6 (adenine group) 



HO 



It is easy to see that by drastic hydrolysis such a sub- 

 stance can be converted into phosphoric acid, H 3 PO 4 , a 

 hexose, C 6 H 12 O 6 , and four different nitrogenous substances, 

 namely, guanine, thymine, cytosine, and adenine. By less 

 drastic methods of hydrolysis nucleotides can be obtained 

 the thymine nucleotide, for example, which has been 

 actually isolated in a pure state, and has the formula 



HO 



o \ po CH Q _ c N 



HO 



