Chemical Constituents of the Animal Body. 207 



By methods of reaction III., it is possible to pass from 

 the lower to a higher sugar. A new asymmetric carbon 

 atom will be introduced, and from each tetrose two pen- 

 toses can be obtained. It is not necessary to give the 

 formulae of all the eight possible pentoses ; it will be 

 sufficient to consider those derived from any two tetroses, 

 say those of formulae (1) and (3) 



(1) CHO (A) CHO (B) CHO 



CH 2 OH CH 2 OH 



The four synthetically-obtained pentoses will give rise 

 on oxidation to the following dibasic acids (trihydroxy 

 glutaric acids) 



(A) COOH (B) COOH (C) COOH (D) COOH 



-OH 

 -H 

 -OH 

 COOH 



