FURTHER STUDIES ON ARTIFICIAL PARTHENOCARPY

IN THIS study on induced parthenocarpy the writer has had two objects in mind: to test out new compounds and to obtain further information on the mechanism of fruit development. The following new compounds have been used: 9,10-di-n-propyl-9,10dihydroxy 9,10 dihydro-1 ,2,5,6-dibenzanthracene and its potassium salt; 9-phenanthrylacetic acid and its potassium salt; theelin (oestrone); methyleholanthrene; Skatol; crude oestrin from pregnancy urine; 1,2,5,6-dibenzanthracene; N-methyl-pyrrole-2,5-dipropionic acid; pyrrole-%-acetic acid; pyrrole-om-carboxylie acid; and the potassium indole acetate. These compounds were chosen for various reasons. Some were chosen because they have shown oestrogenic properties, others because of carcenogenic activities, others because they have been reported to cause growth in plants, while still others were chosen because it was thought there might be a correlation betwveen inolecular structure and effectiveness in stimulating fruit development. The first four compounds were synthesized by Prof. Bachmann, and the pyrrole compounds were made by Mr. Safir, under the direction of Prof. Blicke, all of the Chemistry Department at the University of Michigan. The potassium indole acetate was made from indole acetic acid bought from Eastman Kodak Company. At the time the potassium indole acetate was made and used in experiments with tobacco, there was no published record of it having been used as a growth hormone, but since then Avery, Burkholder, and Creighton (1937) and also Zimmerman and Hitchcock (1937) have published on its groxvth activity. It should, however, be remembered that salts have previously been supplied to plants in buffered growth substance solutions, and in 1935 Thimann used the sodium salts of indole-, indene-, and cumaryl-acetic acids. The pyrrole compounds have not been used heretofore as growthpromoting substances. Their synthesis is exceedingly difficult. In examining the structure of the compounds that have been found to be active, it occurred to the writer that the pyrrole group might be the active radiele in the indole compounds. Pyrrole acetic, -propionic, and -butyric acids were not available