B. ESTHER STRUCKMEYER 173 



Sections of the stem were also prepared for microincineration. The 

 mineral residue was recorded by means of photomicrographs to deter- 

 mine the distribution of minerals. The greatest amount of mineral 

 residue was present in stems grown with a complete nutrient solution 

 and treated with a-naphthaleneacetamide; stems of plants grown with a 

 complete nutrient supply had the next greatest amount; stems of plants 

 grown without calcium but treated with a-naphthaleneacetamide had a 

 mineral distribution closely resembhng the control plants; and stems of 

 plants grown without calcium showed the least amount of mineral 

 residue. When microchemical tests for calcium were made with 2 per 

 cent sulphuric acid, a positive test was obtained for all four treatments. 

 The exact role of a-naphthaleneacetamide in delaying calcium deficiency 

 symptoms is not known. It may permit greater uptake of calcium from 

 the soil or there may be a conversion of calcium from a relatively 

 immobile to a mobile form. The available supply of calcium would then 

 make possible normal growth of cells. 



Since a-naphthaleneacetamide induces cambial activity, a greater 

 thickening of cell walls, and lignification, hemp plants were sprayed with 

 an aqueous solution of a-naphthaleneacetamide and others received an 

 application of this growth substance in lanolin to the fourth internode 

 from the stem tip. The plants were in a vegetative condition when the 

 treatments were made. Sixteen days after treatment the plants were 

 sampled for anatomical studies. The second internodes of the controls 

 and those treated with a-naphthaleneacetamide showed no thickening 

 of the fibers (Fig. 28, 29, 30). The fourth internode of the control plants 

 showed no thickening of the fibers (Fig. 31); whereas the stems treated 

 with a-naphthaleneacetamide showed a thickening of the walls of the 

 fibers (Fig. 32, 33). In the sixth internodes the controls and those treated 

 with the grov/th substance had thick-walled fibers (Fig. 34, 35, 36). There 

 appeared to be little difference in the number of fibers with these three 

 treatments, but the wall thickening was greater in stems that were 

 treated with the a-naphthaleneacetamide in lanolin. 



It has frequently been shown that chemicals can be used to set fruit. 

 It was found that a 0.5 per cent mixture of /5-naphthoxyacetic acid could 

 be used to set fruits satisfactorily, but that frequently the paste came in 

 contact with ovaries resulting in misshapen fruit. Therefore the spray 

 method was used at a concentration of 75 milligrams per hter. Cross 

 sections of the nearly mature fruit showed the absence of seed in the 



