When we leave the questions of impulse transmission on long fibers and peripheral junctions, however, and attempt to discuss the brain, there can be hardly any doubt that the development of a meaningful physical model technique would be of great value. Brain tissue is soft and sensitive, the cellular structures are small, tangled, and incredibly numerous. Therefore (Young (24)), “ ... physiologists hope that after having learned a lot about nerve-impulses in the nerves they will be able to go on to study how these impulses interact when they reach the brain. [But], we must not assume that we shall understand the brain only in the terms we have learned to use for the nerves. The function of nerves is to carry impulses—like telegraph wires. The functions of brains is something else.” But, confronted with such awesome experimental difficulties, with no comprehensive mathematical theory in sight, we are largely limited otherwise to verbal discourses, rationales and theorizing, a hopelessly clumsy tool for the development of an adequate understanding of brain function. A little over ten years ago Sperry (19) said, “Present day science is quite at a loss even to begin to describe the neural events involved in the simplest form of mental activity.” This situation has not changed much today. The development, study, and understanding of complex high-density cellular structures which incorporate characteristics of both the Lillie and Pask models may, it is hoped, alleviate this situation. There would also be fairly obvious technological applications for such techniques if highly developed and which, more than any other consideration, has prompted support for this work. Experiments to date have been devised which demonstrate the following basic physical functional characteristics: (1) Control of bulk resistivity of electrolytes containing closely-packed, poorly-conducting pellets (2) Circulation of regenerative waves on closed loops (3) Strong coupling between isolated excitable sites (4) Logically-complete wave interactions, including facilitation and annihilation (5) Dendrite growth by electrodeposition in “closed” excitable systems (6) Subthreshold distributed field effects, especially in locally-refractory regions. In addition, our attention has necessarily been directed to various problems of general experimental technique and choice of materials, especially as related to stability, fast recovery and long life. However, in order to understand the possible significance of, and motivation for such experiments, some related modern concepts of neurophysiology, histology and psychology will be reviewed very briefly. These concepts are, respectively: (1) Cellular structure in the central nervous system (2) Short-term or “ephemeral” memory (3) The synapse (4) Inhibition (5) Long-term memory traces or engram (6) Spatially-diffuse temporal association and learning.