1. Alberda, Th., 1948: The influence of some external factors on growth and phosphate uptake of maize plants of different salt conditions. Rec. Trav. Bot. N�erl.41, 541?601.
2. Alexander, J., 1948: Life. Reinhold Publ. Corp., New York.
3. Andel, O. M. van, 1952: Determinations of the osmotic value of exudation sap by means of the thermo-electric method of Baldes and Johnson. Proc. Kon. Ned. Akad. Wet., Ser. C55, 40?48.
4. ?, 1953: The influence of salts on the exudation of tomatoplants. Acta Bot. Neerl.2, 445?521.
5. Arens, K., 1949: The active membrane. An hypothesis to explain the transfer of water and solutes in plants as depending upon respiration. Rev. canad. Biol.8, 157?172.