PARTHENOCARPY can be induced in, among other plants, the common edible members of Solanaceae and Cucurbitaceae by artificial treatment of the unfertilized ovary with pollens of a different family1, pollen extracts2,3, many growth-promoting substances like indole-acetic acid3,4, and even manganese salts5. All the inducing agents so far employed, including manganese salts, have been shown either to contain auxin or to be auxin-like in their physiological activities. These facts have led to the hypothesis proposed by Gustafson3 that growth hormones are essential for the initiation and maintenance of fruit development, and recent experimental evidence seems to support this view5. While there is no doubt that growth hormones, denned as they are, play a dominant part in fruit development, it is still a question whether auxins or auxin-like substances alone can induce parthenocarpy; for we have been able to induce parthenocarpy in members of these two families with fluorescein, a substance known to act on plants sometimes antagonistically to auxins.