64 F. EDMUND HUNTER, JR. 



block low concentrations of dihydroxy acids (Fig. 17). It is also of some 

 interest that dehydroascorbate shows steadily increasing antagonism of 

 ascorbate action as the concentration is raised to 10 mM. 



0.5 



40 60 



Ml N UTES 



Fig. 16. Ascorbate-like lysis of mitochondria produced by certain substances 

 with related structures. Note especially the marked differences in the lag period. 



20 



40 60 



MINUTES 



80 



Fig. 17. Inhibition of ascorbate-induced lysis of mitochondria by high con- 

 centrations of dihydroxyfumarate (DHF) and dehydroascorbate (DHA). 

 Inhibition of DHF-induced lysis by high concentrations of ascorbate. 



More knowledge concerning what is happening during the lag period 

 undoubtedly would tell us something about the mechanism of action of 

 ascorbate. We have very little information on this point. In fact some 

 titrations with indophenol raise a question as to whether ascorbate is 

 disappearing. More experiments are needed. However, in the course of 



