1. Pollen tube growth in vitro is accelerated by addition of sugar. 2. Gravitation has no influence whatever on the direction of growth of the pollen tubes. 3. In the flowers of Narcissus Pseudonarcissus L. var. Golden Harvest potential differences could be shown, in such a way that the ovary is negative both with respect to the pedicel and the stigma. 4. There is a small potential difference between the stigma and the top of the ovary. 5. Pollen tubes of Narcissus grow in vitro in the direction of the cathode and are inhibited in the direction of the anode at a potential difference of about 0.5 volt per cm.