650 



P. W. Brian and H. G. 



Hemming 



Table 7. Effect of azaserine (AZS) and 6-diazo-5-oxo-L-norleu- 

 cine (DON) on response of 'Meteor' pea stem sections to light. Basal 

 medium: 10 Mg/ml indoleacetic acid + 1 per cent sucrose in 

 phosphate buffer. 



Significant difference between means: 0.36 (P = 0.05), 0.48 

 (P = 0.01), 0.61 (P = 0.001). 



and L-glutamine. In their effect on photosynthesis they leave the car- 

 bon cycle untouched but block transamination reactions, and the 

 effect of AZS has been partially reversed by L-glutamine (1). We have 

 examined the possibility of reversal of DON and AZS inhibition of 

 section extension and have tested a large number of purines, pyrimi- 

 dines, nucleosides, and amino acids. The only substance which has 

 shown any evidence of reversal is L-glutamine, but the effect is at 

 most very slight. Thus we have little information concerning the mode 



Table 8. Effect of starvation of 'Meteor' pea stem sections on response (A) to 

 indoleacetic acid (10 Mg/ml) and sucrose (2 per cent) and (B) to gibberellic acid. Data 

 from three experiments in each case. [Mean final lengths of sections (initial length 5.1 

 mm. untreated, 5.4 mm. after starvation treatment). Basal media: (A) phosphate 

 buffer, (B) 10 Mg/ml lAA + 2 per cent sucrose in buffer.] 



B 



.Siirnilicant difference between means of all experiments: 0.28 (P = .05), 0.37 

 (P = .01), 0.48 (P = .001). 



