1. Ramón y Cajal, S., Trab. Lab. Invest. Biol. Univ. Madr., 29, 1 (1934); “Neuron Theory or Reticular Theory?” (Instituto Ramón y Cajal, Madrid, 1954).
2. Fox, C. A., and Barnard, J. W., J. Anat., 91, 299 (1957).
3. Sholl, D. A., “The Organisation of the Cerebral Cortex” (Methuen, 1956).
4. Gray, E. G., J. Anat. (in the press).
5. Gray, E. G., J. Physiol., 145, 25P (1959).