1. Madec, P., in The Growth of the Potato (edit. by Ivins, J., and Milthorpe, F.), 121 (Butterworth, London, 1963).
2. Courduroux, J., thesis, Univ. Clermont-Ferrand, 323 (1967).
3. Humphries, E. C., Ann. Appl. Biol., 46, 346 (1958).
4. Okazawa, Y., J. Fac. Agric. Hokkaido Univ., Sapporo, 55 (3), 267 (1967).
5. Smith, O. E., and Rappaport, L., Amer. Potato J. (in the press).