1. D. A. Sholl, The Organisation of the Cerebral Cortex (Methuen, London, 1956 ). The comparison depends on what is meant by a component. We refer here to the level of a gate and of a neuron, respectively.
2. A. N. Chomsky, Aspects of the Theory of Syntax ( MIT Press, Cambridge, Mass., 1965 ).
3. D. Marr and T. Poggio, Neurosci. Res. Prog. Bull.,in press (also available as Mass. Inst. Technol. Actif. Intell. Lab. Memo 357).
4. H. Haken, Ed. Synergetics-Cooperative Phenomena in Multicomponent Systems ( Teuber, Stuttgart, 1973 ).
5. H. Haken, Rev. Mod. Phys. 47, 67 (1975).