196 



A. M. MAYER 



TABLE IV 



THE EFFECT OF THIOUREA ill VIVO AND in vitrO ON THE ACTIVITY OF OXIDATIVE 

 ENZYMES IN GERMINATING LETTUCE SEED 



In vivo: seeds germinated in thiourea (1250 p. p.m.). No thiiourea present 



in the reaction mixture. 

 In vitro: seeds germinated in water and thiourea was added to the reaction 



mixture. 



Enzyme 



Effect on activity 

 in vivo 



Effect on activity 

 in vitro 



Reference 



cycle in very young 

 seedlings but has no 

 effect on the activity of 

 mitochondria isolated 

 from other seedlings 



proceeds-^' ^■-' ^^ (Table IV). This finding must be contrasted with 

 what occurs in seeds whose dormancy is altered. 



Coumarin, generally speaking, retards or prevents the 

 development of, or increase in activity of the above enzyme 

 system. In no case has a direct effect of coumarin in any of the 

 systems mentioned in vitro been found. This observation can be 

 extended by noting that the entire glycolytic system functions 



