PLANT HORMONES 



217 



FiGUKE 80. Inhibition of growth followed by increase in diameter of stem. A, Sweet 

 pea seedhngs showing controls (right), and seedlings treated at the tip with lanohn prep- 

 aration containing 1 per cent a-naphthaleneacetic acid. B, Windsor bean seedhngs 

 showing upright controls, not treated, and treated seedlings which are inhibited and 

 swollen. C, Potato sprouts showing upright controls {right) and curved and swollen 

 sprouts resulting from treatment with lanolin preparation containing about 1 per cent 

 /3-indoleacetic acid. D, Potato sprouts showing inhibition of growth and swelling after 

 treatment with lanolin preparation containing about 1 per cent a-naphthaleneacetic 

 acid. Controls shown iu C. 



