PROPERTIES OF GROWTH SUBSTANCES 53 



Skatole (3-methyl indole) has been reported by Glover (1936) 

 to be active in the Avena test. 



Zimmerman and Wilcoxon (1935) have tested several com- 

 pounds for their ability to cause bending of the stems of the 

 sweet pea and other plants. Not all of these compounds have 

 yet been tested on the Avena coleoptile. 



The same compounds also induce rooting responses in stems of 

 Nicotiana, Lycopersicon, etc., when applied in solution to the 

 soil, injected into the stem, or applied in lanolin directly on the 

 stems. Ethylene and propylene are reported effective when 

 applied in lanolin, and carbon monoxide and ethylene induce 

 roots to grow on stems of numerous species (Zimmerman, 

 Crocker, and Hitchcock, 1933a, b; Zimmerman and Hitchcock, 

 1933). 



Bauguess (1935) has tested several indole derivatives, ^^^th 

 resulting root initiation, stem bending, and bud inhibition in 

 tomatoes, marigolds, and stocks; they are i3-3-indole propionic 

 acid, j8-4-indole butyric acid, j3-3-indole pyruvic acid, /S-3-indole 

 a-oximino propionic acid and |3-3-indole acrylic acid, all of which 

 are active. The only inactive compound tested was dl-i3-3-indole 

 lactic acid. 



Haagen Smit and Went (1935) have reported on the activity 

 of the following additional compounds. If the effectiveness of 

 3-indole acetic acid is considered as 1, the values are as 

 follows : 



