1. Hyden, H., in The Cell, edit. by Brachet, J., and Mirsky, A., 4, 215 (Academic Press, New York, 1960).
2. Gaito, J., Psych. Rev., 70, 471 (1963).
3. Schmitt, F. O., in Macromolecular Specificity and Biological Memory, edit. by Schmitt, F. O., 1 (Mass. Inst. Tech. Press., Camb., 1962).
4. Flexner, J. B., Flexner, L., Stellar, E., de la Haba, G., and Roberts, R. B., J. Neurochem., 9, 595 (1962).
5. Flexner, J. B., Flexner, L., and Stellar, E., Science, 141, 57 (1963).