ZIMMERMAN: FORMATIVE INFLUENCES 99 



preparations were made up with a series of concentrations of the chemical, 

 ranging from 0.005 to 20.0 mg./g. of lanolin. These preparations were applied 

 to local parts of the plant with a glass rod. To induce epinasty the material was 

 applied to the upper side of a young leaf petiole ; to induce curvature of the stem 

 the material was applied along one side of a young stem. Chemicals active for 

 cell elongation caused negative (away from treated side) curvatures within a 

 short time. The same treatment also served to determine whether the chemicals 

 had a formative influence on new growth. Plants were exposed to vapors of 

 the various compounds under bell jars, closed greenhouses, glass cages, or 

 other closed containers which could be kept reasonably tight. The esters were 

 more volatile than acids or amides and were considered best for vapor treat- 

 ments. The ultimate effects, however, were the same for all. The amount of 

 ester required under the bell jar was less than 1 milligram. When heat was re- 

 quired to volatilize the chemical, a small amount was placed on a watch glass 

 which in turn was placed on a warm or hot inverted crucible under a bell jar. 

 In the greenhouse a hot plate supplied the heat and an electric fan circulated the 

 air. 



Most of the chemical compounds used in the experiments and listed in the 

 tables were synthesized in the Boyce Thompson Institute laboratories. A few 

 were available from commercial supply houses. 



Results 



For the study of formative influences three groups of compounds stand 

 out above all others. They are ^-naphthoxy acids, substituted phenoxy deriv- 

 atives of the lower fatty acids, and substituted benzoic acids. The substituted 

 groups were nitro, amino, methyl, or halogen radicals. These were used alone or 

 in various combinations substituted in the naphthalene or benzene ring. 



fi-Naphthoxy compounds. /?-Naphthoxyacetic acid and the higher homo- 

 logs, propionic and butyric acids, were the first observed to have special forma- 

 tive influences ( 5 ) . They were found to have in common with other plant hor- 

 mone-like compounds the capacity to cause cell elongation, parthenocarpic de- 

 velopment of ovaries, and to induce roots. Table 1 shows a list of naphthoxy 

 and naphthalene compounds and their activity for cell elongation and formative 

 influences. 



It is interesting to note that for cell elongation naphthoxy compounds must 

 have the chain of the molecule linked to the beta position in the ring while the 

 alpha position is required for naphthaleneacetic acid. a-Naphthoxyacetic acid 

 is inactive for cell elongation but has a slight formative influence. Neither a- 

 nor /^-naphthaleneacetic acid has a formative influence which modifies the pat- 

 tern of leaves. 



