1. Hardy, A. C., and Bainbridge, R., Nature, 167, 354 (1951).
2. Knight-Jones, E. W., and Qasim, S. Z., Nature, 175, 941 (1955).
3. Baylor, E. R., and Smith, F. E., Recent Adv. Invert. Physiol., 21 (Oregon, 1957).
4. Kortum, G., and Bockris, J. O'M., Textbook of Electrochemistry (Elsevier Pub. Co., London, 1951).
5. Harris, E. J., Transport and Accumulation in Biological Systems, second edit. (Butterworth, London, 1960).