466 



FURTHER EVOLUTION 



GLUCOSE 



OXALOACETIC 

 ACID 



MALIC 

 ACID 



CIS-ACONITIC 

 ACID 



COOH 



I 



CH 



FUMARIC \ II 

 ACID 



SUCCINIC 

 ACID 



•HjO ''"'' 6 / ^"-^ OXALOSUCCINIC 



CO, f CO I ^(^10 



COOH ^2 COOH 



a-OXOGLUTARIC 

 ACID 



Fig. 40. The tricarboxylic cycle (after Krebs). 



