The Uptake and Transport of 14C in Cells of Conocephalum conicum L. in Light

Dissolved inorganic ¹⁴carbon, fed to a small portion of thetissue of Conocephalun conicum, travelled along the tissuesfrom cell to cell at rates of about 2.0 to 1.7 µm 5^–1,which is of the same order of magnitude as streaming rates inthese cells. Trans-cellular transport can take place againsta pressure gradient, but pressure gradients of 200 kPa or morein either direction reduced the trans-cellular transport significantlywithout reducing streaming rate and are, therefore, thoughtto have induced ‘valving’ effects at the plasmodesmata.Ammonium ion reduced or inhibited transport without reducingstreaming rates and is, therefore, thought to have inhibitedan active component in the plasmodesmata. Thus the results obtainedfrom tandem cells of Nitella can be transferred to tissues. Key words: Conocephalum, transport, plasmodesmata