Fig. 4. — Rooting response of cuttings of American holly. The 

 bottom row had had their lower ends dipped for 54 hours in a 

 solution of 10 mg. of indole-acetic acid in 100 ml. of water. 

 The top row was placed in tap water for the same time. All 

 cuttings were then put into a compost of peat-moss and sand 

 for five weeks before the photograph was taken. 



Fig. 5. — Two sets of cuttings similar to those of Fig. 4, except 

 that the lower row of cuttings were dipped for four days in a 

 solution of 2 mg. of a-naphthalene-acetic acid per 100 ml. 

 water, the controls being put into tap water for four days. 



