Scientific Results 

 He wrote: 



"By the spray method of applying the growth-substances 

 to the aerial parts of plants, uniform entry of the substance 

 is secured so that no bending of the stem occurs. . . . The 

 experiments described have shown that with the treatment 

 given the growth-substances cause no increased growth of 

 the plant as a whole, but exert, on the other hand, a reducing 

 effect. With the appropriate concentration, this reduction is 

 minimal. 



"... The treatments seem to have a very large effect 

 on the way in which plant capital is distributed. The 

 substances do in fact appear to control the amount of 

 plant capital that shall go to the making up of each particu- 

 lar organ, without altering the total amount of plant 

 material." 



Templeman (1938) obtained decreases, but no increases, in 

 dry-matter production of plants grown in pots of sand, by 

 spraying the foliage or watering the sand with indole-acetic or 

 a-naphthyl-acetic acids, ascorbic acid (vitamin C), or skatole. 



Uptake from Soil 



Hitchcock and Zimmerman (1935) reported that the addi- 

 tion of synthetic growth substances to soil induced all the 

 responses previously observed by them after applying the 

 materials to the aerial parts of plants. There were differences 

 in the extent and rapidity of response to substances applied to 

 soil, these differences depending not only on the species of 

 plants, but also upon the type of growth, magnitude, and 

 environment of the plant. As before, only a few results can 

 be quoted here. The plants were grown in 4-inch pots holding 

 the equivalent of about 450 gm. of air-dry soil. The solutions 

 were made by extensive dilution with water of an alcohol 

 solution of each compound. Phenyl-acetic, phenyl-propionic, 

 indole-acetic, -butyric, and -propionic, and naphthalene- 

 acetic [? a] acids were tried. 



Epinasty (downward bending) of some or all leaves of 



33 



