134 



PLANT GROWTH SUBSTANCES 



MILLIVOLTS 



+ 60- 



+ 50- 



+ 40- 



+ 20- 



+ 10 



+ 30- 



Figure 5. Electrical polarities induced by applying 10 microamperes for 

 10 minutes transversely to the Avena coleoptile at 2, 5, 10, 15, 20, and 25 

 millimeters below the apex. Each curve is an average of 10 or more experiments 

 and numbered beginning with the most apical level. 



